Answers to all your questions about COVID vaccines

The main reason why people hesitate to be vaccinated is the fear of having a harmful effect, short or long -term.The fears are even greater with the Vaccines against the COVVI-19, developed in record time.Now is the time to answer questions about this, without sweeping the risks under the carpet.

The information in this article will be updated as the vaccination campaign will unfold in Canada and that new data will be accessible.

Last update: April 9, 2021

Reliability

Les vaccins contre la COVID ont-ils été conçus trop vite ?Afficher la réponse

Are vaccines developed in less than a year as safe as those that are 10 years to develop?Yes.As Mark Toshner, specialist in clinical trials at the University of Cambridge explains (who has not participated in any of the current trials), "these 10 years are not used to ensure that the vaccine is safe;These are years spent fighting indifference, commercial imperatives and bureaucracy ".

The trials of sras-cov-2 vaccines, funded with billions, were not sloppy.Pharmaceutical companies, as usual, made breaks when guinea pigs have had serious illnesses after being inoculated, time to check if the vaccine could be involved.Exceptional fact, they published the protocols of their tests, which allowed the scientific community to criticize them even before the authorities analyze the results.It is under pressure from independent researchers, for example, that the American Food and Drugs (FDA) demanded that companies submit any approval requests before having monitored their guinea pigs for at least two months, and notAs soon as they had enough people vaccinated in the trials, as they were initially planned.Regulatory agencies like Health Canada have also heard with laboratories to receive certain data from tests as you go rather than at the very end, to accelerate the analysis.This way of proceeding, authorized in September under an emergency order, made it possible to accelerate the authorization process without reducing the regulatory requirements on the safety of vaccines.

When a new vaccine is authorized, data on its effectiveness and safety is always partial, since it was obtained as a result of trials carried out on only tens of thousands of people.The trials of sras-cov-2 vaccines made it possible to assess the risks of side effects that would appear in more than one person on a few tens of thousands during the following two months the injection.Apart from occasional and mild effects like headache or fatigue, nothing has been found.

Post -commercialization surveillance, phase 4 of clinical trials, sets out immediately after authorization.It continues continuously as people are vaccinated, which makes it possible to identify rare or long -term effects, if there are any.

With extreme exceptions, all the vaccines that have been authorized worldwide for decades have proven to be very little risky.It is estimated that, each year, vaccination warns two to three million deaths on the planet.Link

Ce sont les tout premiers vaccins à ARN ! Allons-nous servir de cobayes ?Afficher la réponse

Moderna and Pfizer vaccines are the first to use RNA strands to stimulate the immune response.But dozens of other vaccines of this type, against various infectious diseases and cancers, are under study.The first tests on animals date from 30 years, and those conducted on humans go back to 15 years.We still have a good perspective!These vaccines are not likely to give the disease, since they do not contain the slightest particle of the virus: the RNA they contain is made in the laboratory and not extracted from the sras-cov-2.Easy to produce and probably even safer than their ancestors, these vaccines made of synthetic genetic material are considered to be very promising.

It is strictly impossible for the vaccine RNA to change our genes, as some affirm on social networks.On the one hand, it does not enter the nuclei of the cells, where is most of our DNA;On the other hand, it is almost instantly destroyed by our cells.Link

Les vaccins à vecteur viral, qu’est-ce que ça vaut ? (Et que se passe-t-il avec AstraZeneca ?)Afficher la réponse

Astrazeneca and Janssen vaccines use a harmless virus, an adenovirus, which is modified so that it cannot multiply in the human body.The researchers inserted in the DNA of this virus a sequence containing "instructions" in order to allow the virus to produce the Spicule protein, that useful to sras-cov-2 to infect human cells, thus forming what iscalls a viral vector.When this viral vector is injected, it enters our cells where it releases its DNA.Each cell then produces Spicule protein, which immune cells identify as an enemy and fight by triggering the reaction that will make it possible for two to three weeks, the vaccinated person will have developed significant immunity against SRAS-COV-2.

Another already authorized vaccine, against the Ebola virus, also uses a viral vector, and many others are in development.Technology is controlled - it has been studied since the 1970s.

What efficiency?

Astrazeneca accumulates tiles with her vaccine.First, during clinical trials, a fraction of the participants received, by mistake, half a dose of vaccine rather than an entire dose.This has not removed the validity of the trial which made it possible to demonstrate that this vaccine is effective at 71 % after a single dose, and 81 % after two doses if the second is given more than three months after the first.As these percentages are lower than those announced for RNA vaccines, many people thought that the astrazeneca vaccine was less good.However, it is just as effective against the serious effects of COVID which can lead to hospitalizations or death.

On March 22, 2021, Astrazeneca announced in a press release that a new interim analysis of the data collected from 32,449 people who participated in its clinical trials conducted in 88 centers in the United States, Chile and Peru allowed to conclude that theVaccine is 79 % effective to prevent symptoms of COVID and 100 % against forms requiring hospitalization or leading to death, without difference in significant efficiency depending on age or ethnic origin.

This vaccine is still not authorized in the United States, Food and Drug Administration (FDA) required to have more data obtained from American cobayes before allowing Astrazeneca to file a request.And, less than 24 hours after the publication of the March 22 press release, the National Institute of Allergy and Infectious Diseases (Niaid), which Anthony Fauci directs, said that Astrazeneca "could" use outdated data inducing aincomplete interpretation of efficiency.

We understand that it is possible that the company has not respected all the rules imposed by the Niaid when it has disclosed the results relating to the effectiveness of the collected vaccine of this clinical trial.We do not know for the moment if it is a simple administrative hassle or a misunderstanding, or if Astrazeneca has organized to embellish its results in the eyes of the FDA.

Anyway, it is established that this vaccine largely protects against the disease.That its exact efficiency earns or loses some percentage points would not change.In short, we can sleep quietly and bet that this other tile may have much more to do with questions of politics and protectionism than with new doubts about this vaccine.It is certainly no coincidence that the United States, which has given the green light without flinching to the three American vaccines, seem to be very tatillon with the European vaccine of Astrazeneca, which has however already been approved in multiple countriesAt least as demanding as they are!

Thus, during a study conducted in Scotland with 5.4 million people of all ages and various health states to whom this vaccine has already been inoculated, it was 94 % effective against thehospitalizations a month after the first dose, whether it is the original strain of the virus or the British variant.It is enormous !

In addition, since few people over 65 had received the vaccine during the tests, several countries first deemed prudent not to give it to this population.Most have changed themselves since.In Canada, both the National Immunization Advisory Committee and the Quebec Immunization Committee consider it without particular and effective risk for the elders.

It is possible, on the other hand, that this vaccine is less efficient than the others against the South African variant, but nothing is yet sure on this side.

Thrombosis

On March 11, 2021, Denmark, Norway and Iceland temporarily interrupted the administration of the Astrazeneca vaccine, thinking that it may have a link with certain cases of venous thrombosis in vaccinated people, some-one died in the days following the injection.Shortly after, several other countries, such as Germany and France, suspended the administration of the vaccine in turn, until the data was re -examined.

According to the European Medicines Agency, which monitors side effects, only thirty thrombosis took place among the 5 million people already vaccinated on this date in Europe, and there were no more people with thrombosis amongvaccinated people than among those who had not yet been.

Nevertheless, the astrazeneca vaccine could be associated with extremely rare cailli in the brain (called cerebral venous sinuses) affecting little blood in the blood.In people who have received the vaccine, the incidence of these blood clots was between 1 person in 250,000 and 1 in 500,000 people.In comparison, 5 % of patients hospitalized because of COVVID and 1 % of infected but non -hospitalized people have blood clots.An investigation is underway to determine if the cases observed are really linked to the astrazeneca vaccine.

As most cases have occurred in young people, mainly women, as a precaution, the immunization committees of Quebec and Canada have advised temporarily suspending the administration of this vaccine under 55, thetime that this investigation ends.On March 29, the Quebec Ministry of Health and Social Services announced that it has decided to follow this recommendation.

Thrombose Canada, the association of experts who emits guidelines to the country for the management of thrombosis, examined the data and also concluded that people who receive the Astrazeneca vaccine are not exposed to an increased riskblood clot compared to the general population.The association recommends "strongly" the vaccines against the covid, whatever they are, to people who have already had a blood clot, to those of which a family member has already had a clot, to those with a hereditary disordercoagulation (such as the mutation of factor V Leiden) and those who take anticoagulants.

Most countries have started to use the vaccine.This incident therefore demonstrates above all that the monitoring system works very well.Link

Comment puis-je déterminer ce que je risque ?Afficher la réponse

Infectious diseases are much rarer than before, to the point that many people are more concerned with the risks of vaccines than those of the diseases they allow to avoid.A lot of people forgot, for example, that among children who catch measles, an ultra-contact disease, 1 in 1000 makes encephalitis, fatal in 10 % of cases.The combined measles vaccine, rubella and mumps can also cause encephalitis, but only in a child on more than a million who have been vaccinated.It’s 1,000 times less!

Such serious effects of vaccines are extremely rare, and most people recover.Between 2013 and 2017, no death was caused by a vaccine in Canada, out of 103 million doses administered, according to the side effects published by the Canada Public Health Agency.During the same period, 23,000 Canadians died of infectious diseases and more than 10,000 road accidents.

"In addition, we always assess the risks of a vaccine with regard to the burden of the disease," explains the pediatrician-infectiologist Caroline Quach-Thanh, director of the National Advisory Committee for Immunization, which indicates to the federal government which should bevaccinated and with what precautions.In other words, the risks of the vaccine must be compared to the risks of the disease against which it protects us.

We have a pretty good idea of the La Covid burden.First, we know that the Sras-Cov-2 is very contagious: if we came back to a normal life without vaccine or health measures against the virus, each infected person would contaminate two or three others.Our hospitals would be quickly overwhelmed!Even if the risk of dying because of COVVID has decreased since the start of the pandemic, it remains important.For example, among people who suffered from the disease in Quebec between July and December 2020, 1 in 100 people aged 60 to 70 years old, and 1 in 5 among the over 80s.The virus is much less deadly in the youngest, but it can be annoying: among the people who have been suffering from a light form of the disease, 1 in 10 always has symptoms (headache or breathlessness, for example)after a month.Healthy young people are also dead from COVID, without knowing why, like Don Béni Kabangu Nsapu, from Repentigny, 19, who had no risk factor.

Another major point to consider: it is unknown what the long -term after -effects of this virus will be that, in addition to respiratory problems, often causes neurological or cardiac disorders.The infection may not leave consequences, but it is not excluded that it is later noted that it increases the risk of infarction or neurodegenerative diseases. Tant qu’on est dans le doute, autant l’éviter…Link

Peut-on mélanger les vaccins ?Afficher la réponse

Can we receive a dose of the pfizer vaccine then, when it is time, a dose of Moderna's?Or the opposite ?In theory, this is not ideal, since this is not what has been validated in clinical trials.In practice, the risks however seem tiny, as these two vaccines contain similar RNA pieces to stimulate the immune response, and other ingredients that look alike.The immunization committees of Quebec and Canada therefore recommend that, for these two products, if the second dose of the same vaccine is not in stock when it should be given, one dose of the other vaccine replaces it.This is not exceptional: most of the vaccines given in two stages against other diseases are thus interchangeable.For the moment, the doses of these RNA vaccines are not considered interchangeable with the doses of other approved vaccines, based on different technologies.

Receiving several close doses of vaccines against different diseases is not advised as long as there is no evidence that this affects neither the efficiency nor the safety of these products.This could also blur cards for researchers who analyze the incidence of vaccination campaigns.

As the COVVID vaccines are new, the CCNI is advising for the moment to wait two weeks after receiving another vaccine before being immunized against COVVID, and not to receive a vaccine against another disease in the fourfollowing weeks.

However, there is a chance that this period will be abolished after a while.Several vaccines used for decades even immune to different diseases both without reducing their effectiveness, such as the vaccine conjugate measles-rubble-oreillons-varicelle or the Diphtheria-Coqueluche-Tetanos-Hépatitis B-Polio-Hib,Babies are given from the age of two months. Une seule piqûre contre six maladies d’un coup est tout aussi sécuritaire, mais bien moins désagréable pour le bébé et coûteux pour le système de santé !Link

J’ai une maladie chronique, puis-je être vacciné ?Afficher la réponse

There are very few contraindications for covid vaccines, as for the vast majority of vaccines against other diseases.Whether you have hypertension or diabetes or have cholesterol problems, it doesn't bother!However, there are rare exceptions and precautions to take for some people.

In any case, if you have a doubt that a predisposition, a drug or a disease could prevent you from receiving the vaccine, the best person to ask the question is your doctor.You should not trust rumors about social media or discussions on online forums, which are infiltrated by anti -vaccino movements, which express themselves to scare with arguments that have no scientific value.Link

Est-ce que les vaccins peuvent interagir avec des médicaments ?Afficher la réponse

Until now, there has been no interaction between a covid vaccine and drugs.As a general rule, there is very little risk that an interaction vaccine with any medication, with the exception of immunosuppressants and antivirals.There is a theoretical risk that RNA or viral vector vaccines lead to false negative results with two tests used to diagnose tuberculosis: the skin test for tuberculin and the gamma interferon liberation test.If these tests are necessary, it is recommended to pass them before vaccination or more than a month after.Link

The side effects

Vais-je ressentir des effets désagréables, comme de la fièvre, après l’injection ?Afficher la réponse

Among the people who will receive the vaccines of Pfizer or Moderna, we expect more than 1 in 10 to have a fever, 1 in 2 of headaches or fatigue, 1 in 3 of aches or chills, and 1 in 5 joint pain, within hours of injection and to, as much as possible, a few days.After the second dose, the reactions will be more pronounced, but without danger.We can take acetaminophen (tylenol or other brand) to relieve ourselves, this will not remove any effectiveness in the vaccine.Other vaccines, such as Shingrix, given to prevent zona, have the same kind of reactogenous effect.Specialists believe that the reactions trained will be more marked with the COVVID vaccine than with that against the flu.

Ian Haydon, a 29 -year -old scientific communicator, was one of the first guinea pigs to receive the Moderna vaccine during phase 1, in May.It has received a dose of 250 micrograms, 2.5 times the one found today in the vaccine.Following the first injection, he simply had a sore arm.But 12 hours after the second, administered three weeks later, its temperature climbed to 39.4 ° C.Nauseous, he vomited, then passed out.After an afternoon in bed, everything returned to order."I have no consequences and did not have the covid since.Everything is fine for me!He said to me, laughing.Knowing that at his age, the virus could not have drawn up any symptoms, does he regret his choice?"Not a second!This pandemic reminds us that we must all think beyond ourselves, "says Ian Haydon, who asks young adults like him to go and be vaccinated.

In phase 3 tests, the majority of guinea pigs have perfectly supported the vaccine.Less than 2 % of vaccinated people saw their temperature rise to more than 39 ° C the next day.

The Astrazeneca vaccine can also cause without danger side effects, such as pain in injection, headache, fatigue and, in less than 1 % of people, a little fever.

The side effects reported in Canadians who have been vaccinated are updated by Health Canada every Friday on this page.Link

Si je n’ai rien senti, est-ce un signe que le vaccin n’a pas fonctionné ? (Nouveau)Afficher la réponseLes effets indésirables sont courants chez les personnes qui viennent d’être vaccinées. La plupart ont juste un peu mal au bras, mais certaines ont une bonne fièvre, des courbatures, ou se sentent fatiguées pendant un ou deux jours. D’autres encore ne ressentent rien du tout et s’en inquiètent : cela signifie-t-il que, dans leur cas, le vaccin n’a pas fonctionné ? « Pas du tout, répond l’immunologiste Alain Lamarre, professeur à l’Institut national de la recherche scientifique (INRS), à Laval. Il n’y a pas de corrélation entre les effets indésirables et l’efficacité des vaccins. On peut parfaitement être en train de fabriquer des anticorps, ou de produire des cellules mémoire, sans que rien nous l’indique. »

We see it by examining the figures.For example, during the clinical trial led by Pfizer, during which the side effects were monitored very strictly in the 21,700 people who received the vaccine, 2 out of 10 - and 3 out of 10 in over 55s -did not even have a hand in the arm after their injection.More than half of all participants have not had the slightest "systemic" reaction, such as fever, fatigue or headache.For the anecdote, it should be noted that almost a quarter of the 21,728 people who had received the Placébo noted fatigue, a sign that the side effects are not all due to the immune response!

During this trial, the effectiveness of the COVVI-19 vaccine was estimated at 95 %.This figure does not mean that among 100 people who received it, only 95 are protected, but rather than for the vaccinated group, the risk of developing the disease decreased by 95 %.Only 8 people had COVVID (all light forms) in this group, or 0.04 % of guinea pigs.If the 4,370 people who had absolutely no adverse effects had not been protected against the virus, many more of them would have been infected despite the vaccine!In the Placébo group, 162 people had COVVI.

We do not know how many people have had undesirable effects since this vaccine is administered on a large scale, since most people do not report these benign reactions.In Canada, so far, side effects have been declared to Health Canada for only 0.06 % of the 4.8 million doses injected, and serious effects were reported for 0.008 % of doses.We know on the other hand, thanks to the studies carried out in Israel in particular, that this vaccine actually has an effectiveness of around 95 %.

An arm pain indicates local inflammation, a sign that cells in the immune system have activated there, and so -called "systemic" reactions as fever indicate that the immune system as a whole has mobilized.But the reverse is not true.

Reactogenicity, that is to say the fact that a vaccine produces adverse effects in the hours following its injection, is often more frequent in young people, and it could indicate that the immune reaction quickly starts.But that does not mean that all this answer, which concerns several types of cells and will eventually create sustainable immunity against the virus, will be faster or more efficient.On average, it takes about two weeks, three for older people.

Furthermore, even if we know that reactogenicity is on average more frequent in young people, they will not all have a reaction marked in the vaccine."On an individual level, we do not know why some people react more or less than others," explains Alain Lamarre.Genetics, state of health, microbiota ... countless elements influence the immune reactions of each person, which means that it is impossible to predict which will have what adverse effect, no more than we can guess whatNot everyone will be protected.Link

Vais-je faire une réaction allergique ?Afficher la réponse

From the start of the COVVI-19 vaccination campaigns, several cases of anaphylaxis, a serious allergic reaction, made the headlines and worries the authorities, which activated surveillance mechanisms.

Anaphylaxis can occur within minutes of the injection of any vaccine, in anyone - hence the obligation to stay 15 minutes under observation.It is very rare, occurring on average in 1 person vaccinated out of 770,000.And it is almost never fatal, since surveillance makes it possible to counter it immediately with an adrenaline injection.We risk as much to have an allergic reaction to a vaccine as to be struck by lightning ... which kills much more often.

Health Canada publishes the number of unwanted reactions on Friday at this address.Dated February 26, 46 cases of anaphylaxis occurred, out of 1,778,405 doses of Pfizer and Moderna vaccines already administered (about 1 case for 39,000 injections).

It is suspected that this surplus of reactions in relation to what was expected is due to the polyethylene glycol (PEG) molecule, which is attached to one of the lipids coated with the present in Moderna and Pfizer vaccines.PEG is used to stabilize this fat to protect the precious RNA until it enters the cells where it will trigger the immune response.

PEG is a frequent ingredient in toothpaste, shampoos, cosmetics, cough syrups or corneal lentil solutions, and there are also in many drugs not particularly dangerous.We have been found for decades in most laxative products.

PEG allergies are as rare as it is poorly understood.Some researchers who have been interested in it even hesitate to qualify as real allergy the reaction that this molecule can cause, since it does not increase the secretion of IgE immunoglobulin as do all other allergens in sensitive people.But the PEG is already in the crosshairs of vaccine manufacturers: last September, Moderna researchers published a study presenting a substitution molecule which could be used as stabilizer of lipid nanoparticles in RNA vaccines.

In an analysis of the centers for Disease Control and Prevention (CDC) published in January, among the 21 Americans with whom the Pfizer vaccine sparked an anaphylactic reaction, 17 already had a known allergy to one or more substances - notably the venom ofBee, eggs, nuts, penicillin, the influenza vaccine - and 7 of them had already suffered from an anaphylactic shock.

The vaccine therefore seems more risky for people who already have allergies ... even if the vast majority of them will receive it without any problem.The study of CDC does not indicate the number of people who are successfully vaccinated, but they were undoubtedly very numerous, in view of the high prevalence of allergies in the population: in the United States, for example, 1 adult out of 20has already had a serious allergic reaction to a food!

Most allergic people can also receive the majority of vaccines without any problem - even those likely to contain traces of eggs are no longer not recommended for people who are allergic to this food.The contraindications are known and taken into account.

Health Canada, like many other authorities around the world, therefore continues to estimate that only people who have already had a serious allergic reaction to one of the ingredients of the COVVID vaccines should not be immune, since in theircase, the probability of such a reaction is very high.

All other allergic people should ideally receive the vaccine.Those who have already reacted seriously to a vaccine should stay in surveillance 30 minutes rather than 15, advise Health Canada as well as, in particular, WHO.

Des réponses à toutes vos questions sur les vaccins contre la COVID

Last clarification: in some people, whether allergic or not, vaccination causes intense stress whose manifestations, all benign, sometimes resemble those of anaphylaxis: spasm of the sob in babies, syncope (especially in adolescentsand young adults) or anxiety crisis.They are generally avoidable if we take the time to relax before injection, and we talk about our stress to the vaccinator.Link

Le vaccin peut-il détraquer mon immunité ?Afficher la réponse

The new vaccines often arouse controversy and sometimes increase the number of autoimmune disease declarations, as vaccinated people and health professionals are on the alert.But after investigation, we see that very few of these diseases are linked to the vaccine, when there is no.

In France, for example, dozens of young women have continued manufacturers of vaccines against the human papillom virus (HPV) from 2006 to 2008 because they had started to suffer from multiple sclerosis or lupus in the following monthsThe injections.But numerous studies carried out later with millions of young women have shown that those who had been vaccinated were not more often affected by these diseases than others.About 30 million doses of HPV vaccine are injected into the world each year and there has never been a link with autoimmune diseases.

We know that vaccines can, very rarely, trigger Guillain-Barré syndrome, a neurological disease.But the majority of cases occur in the population are due ... to bacteria and viruses.Some cases were also diagnosed after an infection by the Sras-Cov-2.Most affected people are recovering after a few months, a third can keep partially in the face or arms paralysis, and this syndrome is fatal in 2 % of cases.In 2009, the massive vaccination campaign against the H1N1 virus in Quebec caused a surplus of two cases of Guillain-Barré per million doses of vaccine administered.No one died.

Immunode -depressed people can also freely receive vaccines, on the advice of their doctor, who may check whether readjustments to their treatments are necessary.Link

Les vaccins contre la COVID sont-ils dangereux pour les enfants et les femmes enceintes ?Afficher la réponse

Current vaccines are authorized for 18 years and over, with the exception of that of Pfizer, which can be injected for 16 and over.However, derogations are possible for children aged 12 and over who present a particularly high risk of contracting COVVID and developing a serious form of the disease because of their underlying state of health.For adolescents, trials have started and will be followed by trials on the youngest.

Vaccines are just starting to be tested on pregnant women, who run a higher risk of COVID complications than women of the same age that are not pregnant.Until recently, this risk difference seemed minor, but a review of scientific literature published on March 19 by researcher Nathalie Auger, from the CHUM, in the newspaper of the Canadian Medical Association shows that she is really worrying.The analysis of this epidemiologist specializing in perinatal studies thus reveals that contracting the virus by being pregnant seems to significantly increase the risk of preeclampsia, premature birth, from birth by cesarean, low birth weight and to have a dead babyborn.

As nothing indicates that vaccines will be particularly risky for these women and their children to be born, the immunization committees recommend that pregnant women who are exposed to a great risk of contracting the virus, or which are affected by certain comorbidities,Like diabetes or obesity, which increase the danger of suffering from serious shapes of covid, can be vaccinated if they wish, after having been warned that the vaccines have not yet been rigorously tested in this case.

Breastfeeding women have also been excluded from clinical trials that conducted to the authorization of COVVI.Nevertheless, the immunization committees also recommend offering the vaccine already to those who are part of priority groups, such as health workers or people suffering from certain diseases.Vaccines present no theoretical risk for mothers as well as for their breastfed babies.Link

Le vaccin pourrait-il me rendre encore plus sensible à la COVID ?Afficher la réponse

Could some vaccinated people, if they caught the virus later in their lives, become even more sick than if they had not received the vaccine?A few months ago, this possibility seriously worried about many specialists, such as Brian Ward, professor of infectious diseases at McGill and doctor for Medicago, Quebec.This effect called a "disease aggravated by vaccination", or VAED (Vaccine-associated enhanced Disease), has not often been observed in the history of vaccination.It happened in the 1960s with a vaccine against measles and another against the syncytial respiratory virus (the bronchiolitis manager), which were abandoned;Then in 2008 with an experimental HIV vaccine, which was never marketed;and finally in 2017 with a denguenging vaccine, Dengvaxia.By following the 700,000 children who received this vaccine in the Philippines, it has been found that 2 % of them had suffered from a serious dengue infection in the months after.Many died.Among children who had dengue without being vaccinated, mortality was 1 %.The vaccination campaign immediately ceased.

During the tests of vaccine against the Sras-Cov-1 and the Mers-Cov (the two dangerous coronaviruses appeared before the Sras-Cov-2, which gives the COVVID), researchers had observed clues revealing that this undesirable effect ofvaccines was possible with these viruses.Some hamsters had even had a Vaed after four to six months.This risk was therefore taken into account as soon as the trials of sras-cov-2 vaccines have started, in particular by researchers from the Brighton collaboration, an international grouping of experts who examine the security of vaccines, in which Brian participatesWard.

"Today, we are much less worried, for several reasons," said the specialist, who has already decided that he would be vaccinated."Among around 300,000 people vaccinated during the various clinical trials, fifty had the Covid later, without being more serious than those who had received the placebo.We did not find VAED either during the tests on the monkeys, excellent animal models for the COVID.Studies as to the way in which the virus multiplies in cells are also reassuring: they show that the phenomenon (replication of the virus in cells called macrophages) by which VAED could appear in hamsters with sras-cov-1 does not occur with the sras-cov-2.

Any risk of VAED cannot however be completely excluded.But this theoretically possible effect will be watched closely all over the world, so that we quickly react to the slightest doubt.Link

The effectiveness

Devrais-je insister pour recevoir le vaccin le plus efficace ? (Nouveau)Afficher la réponseDepuis que les premiers vaccins contre la COVID-19 ont été autorisés, on entend beaucoup parler du taux d’efficacité de chacun. Mais si l’on pouvait choisir tel ou tel fabricant, devrait-on le faire sur la base de ces chiffres ?

It must be understood that the effectiveness of a vaccine against a disease indicates its performance on the scale of a population, not an individual.We first calculate the potential efficiency during clinical trials, comparing the number of people who fell sick after receiving the vaccine with the number of people who fell sick after receiving a placebo.For example, in the clinical trial of Pfizer which led to the authorization of its product, 21,700 people received the vaccine and 21,728 received a placebo (in this case, a saline solution which does not cause any immune reaction).From a week after the second dose received by each participant, the researchers recorded the number of cases of covid occurring in each group during a middle period of two months.They found 8 in the vaccinated group and 162 in the placebo group.It is concluded that, on average, people vaccinated during this trial had 95 % less risk of contracting COVVID than those who received placebo.[For the matheux that this would interest, this percentage is obtained by the following operation: (1 - 8/162) x 100 = 95.06.]]

What is real efficiency?

This potential efficiency rate depends on the conditions of the trial: if we had followed people a little longer, or if the people who formed the two groups had had a somewhat different genetics or risk profile,The result could not have been the same.Ditto if the virus had circulated less in their environment.

This is why, for the same vaccine, two clinical trials carried out in two places or at two separate moments can give fairly different efficiency rates.This is what happened with the Astrazeneca vaccine, the potential efficiency of which was estimated at 62.1 % after the clinical trials carried out in Brazil and England, then 76 % at the end ofA new larger trial in the United States

Real efficiency is calculated only once the vaccine has been given to the general population, which counts both many more people (which reduces statistical uncertainty in the calculation) and a more varied profile (thiswhich reduces the biases that could have been introduced by a group of guinea pigs not quite representative of the general population).The first results, with the Pfizer vaccine, came from Israel and established its efficiency against COVVID at 94 %, out of 600,000 people.

But for each person, what does it give?

The effectiveness thus calculated, whether real or potential, does not allow you to know how many vaccinated people have been truly protected against the disease, because this figure indicates the benefit of a group or a population, and not for each individual.An efficiency rate of 95 %, for example, does not mean that out of 100 people vaccinated, only 95 will be protected, as we sometimes understand it.

You can do the analogy with peas of the vegetable patch that we would cook in a saucepan of water.If the water boils, they will be much better cooked than if it barely shudder, for the same cooking period.The efficiency of hot water is better than that of lukewarm water to cook them.But even if the water is quite hot and therefore very effective, there will always be a few less cooked or soft peas on the plate, because not all are strictly identical.Some are bigger, others were perhaps a little less ripe because they were more in the shade when they pushed, and all the plants may not have exactly the same genetics.

Obviously, through the play of probabilities, it would be in the theory always to opt, if it was possible, for the most effective vaccine, just as we will choose the most effective water temperature to cook smallpea.But it is impossible to know if, individually, such or such a person will be better protected with a vaccine rather than another.The response of the immune system is an extremely complex phenomenon, much more complicated to understand that the simple effect of heat on the cooking of a pea!

It is therefore quite possible that, given your genetics, your microbiota or anything else that makes your immune system are what it is, you are better protected by a vaccine which, tothe population scale, however, will have shown less effective than another."We attach great importance to the figures announced on efficiency, but what means that a person will be more or less well protected is probably much more due to their personal characteristics than to the brand of the vaccine," said Alain Lamarre.

There is no test to predict how your immune system will react.After the vaccine, a serological test, which measures the rate of antibodies capable of fighting the virus, gives a clue that a person has been immune, but it is not advisable to do so, because it is not enough:Even with a low antibody rate, we can be perfectly protected by cellular immunity, another part of the immune response, which is much more delicate to assess.Link

Dois-je me faire vacciner si j’ai déjà eu la COVID ?Afficher la réponse

Vaccines can be administered without risk to people who have already had a COVVID diagnosis confirmed by a PCR test.There is no point in passing a serological test, which measures antibodies, before injection.However, since the start of the vaccination campaign, we have observed in Quebec and elsewhere in the world that people who had already had covid had reactogenic effects (fatigue, headache, fever ...) a little more marked than thosewho had never had it.

People who have already had the disease are probably protected by their natural immunity for a period of at least three months, according to what we know so far.Among people who have already had COVVID in the previous three months or even before, the first dose of vaccine acts as a reminder, indicates the Quebec Immunization Committee.Like other authorities, he therefore recommends that people who have already had the disease receive only a dose of vaccine, since studies have concluded that they were then both protected and people who have never had COVVID,But who received the two doses.

Better, on the other hand, avoid receiving a vaccine while you have symptoms from COVID or another infectious disease such as flu, since your immune system is already busy.If ever, by bad luck, you catch the covid shortly after the first dose of the vaccine (which does not instantly protect), you will have to receive the second at the time.Link

Si beaucoup de gens se font vacciner, est-ce que la pandémie va s’arrêter ?Afficher la réponse

It's likely ... but not sure.Currently, it is not known whether the vaccines prevent infections that do not cause any symptoms.If the virus continues to circulate, there will always be people who can contract covid: the rare unlucky people who will be affected by the disease despite the vaccine, and the people who will not want or cannot be vaccinated, such as children andpregnant women at the moment.

Vaccine trials, however, made it possible to determine that they are very effective against covid: they decrease by around 90 % the risk of being sick if you catch the virus.We do not know how long this protection lasts, since we do not yet have enough perspective.If reminders are necessary every six months or each year, it will take a lot of doses to effectively protect the whole planet!If the vaccine prevents infections, which will soon be known, it would be enough that two thirds of the population are vaccinated so that the phenomenon of collective immunity is stated.Failing to find enough people to infect, the virus would disappear from traffic ... and we would be rid of it as long as collective immunity would persist.

The catch is that we cannot know today what will happen.We are therefore faced with a choice: to seize the only chance that we have to defeat this virus by making us massively vaccinating, which represents very minimal risks compared to the La Bardeau de La COVVID and which will certainly save lives, or to stay taken againmonths, even years, with masks, distancing and restrictions on each new wave.Link

Est-ce que le vaccin empêche de transmettre le virus ?Afficher la réponseÀ la veille de Pâques, les Centers for Disease Control and Prevention (CDC) des États-Unis ont autorisé les personnes ayant déjà reçu depuis plus de deux semaines leurs deux doses des vaccins de Pfizer et de Moderna, ou la dose unique du vaccin de Janssen, à se réunir à l’intérieur entre elles, sans masque ni distanciation. Elle autorise aussi les personnes vaccinées à se réunir avec des personnes non vaccinées, issues d’un seul foyer, si celles-ci ne sont pas à risque accru de développer une forme grave de la COVID. Les Américains vaccinés peuvent aussi voyager à l’intérieur des États-Unis sans avoir à passer de tests ou à s’isoler, sauf s’ils ont des symptômes.

This new recommendation occurs a few days after the publication of a new study in which CDC researchers estimated that RNA vaccines (Pfizer and Moderna) reduce the risk of infection by 90% after two doses, and 80% afterOne dose.This study was carried out between December 2020 and March 2021 with 3,950 essential workers who received the Pfizer vaccine, but CDCs judge that its results would be applicable to the two RNA vaccines, because they have the same mode of action.

This new study confirms the preliminary results of other studies carried out by independent researchers and by companies.We learned that the vaccines concerned do not only radically reduce the risk of developing a disease after having contracted the virus, they really prevent it from multiplying in the body.We do not yet know how much the other vaccines also decrease this risk of infection, but the first results obtained by Astrazeneca and Jassen are encouraging.However, it is not yet known whether vaccines are just as effective in preventing infection by new variants, because studies have been carried out mainly when they were little present.

Despite this doubt, CDC experts are reassured enough to give people already vaccinated some air.But this decision is also intended to encourage new people to be immunized as quickly as possible, while Rochelle Walensky, the new CDC director, said feared the arrival of a new devastating wave in the United States, underthe combined effect of new variants and the reduction of restrictions in many states.The number of daily deaths began to go up.

Both in Quebec and in Ottawa, the public health authorities have not yet announced to relax for vaccinated people.Most Canadians have received only one dose of the vaccine, and as the variants circulate more and more actively, it is probably prudent to wait a little that the results of the studies are more convincing.Link

The surveillance

Qu’y a-t-il dans les vaccins ?Afficher la réponse

In RNA vaccines (Pfizer, Moderna)

In the eyes of immunization specialists, the list of ingredients for RNA vaccines is rather simple.Here is, for example, what is found in a dose of the pfizer vaccine.

An active ingredient

This is the active ingredient in the vaccine.The genetic equipment of the SRAS-COV-2 virus is ribonucleic acid, or RNA.RNA is a long molecule made up of a sequence of four nucleotides whose order commands among others the production of different proteins, including the famous protein S (for Spicule, or Spike) with which the virus manages to penetrate our cells.RNA of this virus has around 30,000 nucleotides.

The vaccine contains a piece of RNA made in the laboratory, the sequence of which resembles the part of the virus RNA which controls the production of the protein S.It is called messenger RNA because it carries the instructions that will allow a cell to produce a particular protein.Some of the basics of this synthetic RNA have been modified so that it can better resist in our body until it is decoded.The precise sequence of this modified messenger RNA is an industrial secret.

When the vaccine is injected into the arm muscle, it triggers the immune response by which the body tries to get rid of this intruder.The modified messenger RNA enters inside some of the immune cells, which then produce the protein S, against which the other cells in the immune system deploy their antibody of antibodies.

Fats

The Pfizer vaccine contains four lipids:

This cocktail of fat is designed to coat each RNA molecule in order to protect it and facilitate its entry into immune cells.It contains tiny fat particles, called nanoparticles because their size is-just like that of sras-cov-2-of the order of the hundred nanometers (1 nanometer = 0.000,000 001 meters).When making the vaccine, these nanoparticles are mixed with the RNA to form an emulsion of broken white color, as we do vinaigrette.Cholesterol is used to stabilize this emulsion.Some already marketed drugs, and many others in development, also use lipid nanoparticles as "vector" to transport an active ingredient to the place where it must act.ALC-0159 incorporates a glycol polyethylene molecule, which stabilizes nanoparticles.This ingredient is very common in cosmetics, laxative products and many drugs, many of which are injectable.

Salts

This cocktail of four salts, including sodium chloride (table salt), is mainly used to adjust the pH of the vaccine so that it is identical to that of the human body.Thanks to them, it does not sting when the liquid spreads in the muscle.

Sugar

Ordinary sugar is used to protect nanoparticles from lipid effects from the cold necessary to maintain RNA stability.

Some water

The vaccine is transported in glass vials designed to withstand shock and cold, fitted with a latex cap, to reduce the risk of allergy.Each vial contains four to six doses of vaccine.Once thawed, each dose is diluted with 1.8 milliliter with a saline solution made of water and table salt, before being injected.

In viral vector vaccines

Here, for example, the composition of the Astrazeneca vaccine, which is also quite simple and does not contain any unusual or potentially risky ingredient.

An active ingredient

Chadox1-S: the viral vector.A dose of 0.5 ml contains about 50 billion viral particles.(It may seem huge, but it is not particularly.Do you know that even in fresh and clean air, you probably breathe between 17,000 and 400,000 viruses every minute?)

Fats

These fats protect the viral vector and prevent it from deteriorating too quickly in our cells.

An emulsifier

This common ingredient in drugs and foods prevents soluble materials in water and fats separating into the vaccine and it "sticks" to the glass walls of the vials.

Conservation agents

These products also frequent in drugs and foods add a safety layer by preventing that bacteria can develop in vaccines, even if these are perfectly sterile.The concentration of ethanol is about 1,000 times less than the one that can be found in a beer.

Sugar

This ordinary sugar prevents molecules from deforming during the vaccine production process.It’s the same sugar as the one you eat.

Salt

Table salt is mainly used to adjust the pH of the vaccine so that it is identical to that of the human body.Thanks to him, it does not sting when the liquid spreads in the muscle.

Some water

Enough to dilute the vaccine so that it can be injectable.Link

Qui s’assure que les vaccins sont sécuritaires ?Afficher la réponse

At the end of clinical trials, carried out in hospitals around the world, the laboratory which has developed a vaccine constitutes a thick file presenting the results of the tests and detailing its manufacturing and quality control processes,that he submits to the regulatory authorities of each country.In Canada, specialized health officials in Health Canada analyze these files in detail.They also validate the documentation that the pharmaceutical company will have to give to health professionals and to people who will receive the vaccine.Before it is authorized, various lots provided by the company are tested in the Health Canada laboratories to ensure that quality does not change during production.Then, once the authorization has been given, the program for the registration of Health Canada prizes checks and approves each new lot coming out of the factory before it can be used.In the case of COVVID vaccines, the emergency decree is accompanied by companies that companies must comply with, which forces them in particular to report more real -time safety information in Health Canada, and to follow each person vaccinatedDuring clinical trials for two years.

Some of the data on the vaccine are also validated by the National Consultative Committee for Immunization (CCNI), trained mainly by academics from all over the country. Sur les 91 pages que ce comité a reçues de Pfizer, par exemple, 20 étaient consacrées à la sécurité du vaccin, explique la D^reCaroline Quach-Thanh, qui préside le CCNI.All the undesirable effects listed during the tests are described in detail.About fifty experts usually attend CCNI meetings, including representatives of major medical associations, who can ask their questions.At the end of these deliberations, and after having sometimes conducted additional studies, the committee indicates which can receive the vaccine and the precautions to be taken.The Quebec Immunization Committee (CIQ) then engages in the same exercise.

From the vaccinated person to the World Health Organization (WHO), well -established mechanisms make it possible to detect any serious side effect.This major vaccinovigilance exercise is very effective.

In Canada, anyone, or close to a person, who thinks they had a health problem because of a vaccine, or any health professional who has observed it, can make it an online declaration with a vigilance vigilanceCanada.At this point, no need to prove that there is really a link between the vaccine and the effect felt.

All of these declarations are integrated into the Canadian Side Effects System according to the immunization.Since 1991, this system has also been fueled by impact, a so -called "active surveillance" program led by the 12 largest pediatric hospitals in Canada.“In Sainte-Justine, for example, a nurse is employed full time to scrutinize the medical file of each hospitalized child in order to see which vaccines he received and when.It reports all cases where a disease started after a vaccine, in a time interval which depends on what we know about everyone's possible effects, ”explains the pediatrician-infectiologist Marc Lebel, who supervises the Impact program forThis establishment for 27 years.

Every six months, the Canada Public Health Agency publishes an assessment of "side effects according to immunization", Essi in jargon, distinguishing serious cases, defined as any effect among these"Who leads to death, puts life in danger, demands the hospitalization of the patient or the extension of his hospitalization, leads to a disability or a persistent or marked inability, or leads to a disability or congenital malformation".In 2017, for example, the agency listed 2,960 Esssi (including 253 graves) out of a total of 23 million doses of vaccine administered.All these effects appeared after an injection, but that does not mean that they were caused by the vaccine.

In Quebec, the passive surveillance program of side effects possibly linked to immunization (spiri), managed by the Ministry of Health and Social Services, also analyzes these declarations.

All the ESSIs declared in the world are reported in real time at the Uppsala surveillance center, the large OMS pharmacovigilance center, located in Sweden.The WHO's World Consultative for Vaccination Security, which brings together 14 independent experts, analyzes all reports with regard to scientific literature and can order studies to deepen certain points."We keep a list of all the problems that can arise and we check if this or that vaccine increases the incidence," explains Ève Dubé, anthropologist at Laval University.Specialist in vaccination and the only Canadian to sit on the committee, she ensures that the analyzes he produces cannot be misinterpreted.

The collaboration Brighton, an international organization independent of WHO and manufacturers, also enaches rules which define exactly how each adverse effect should be reported and monitored, all over the world.Nothing is left to chance !

Vaccine manufacturers also have the legal obligation to analyze all the statements of adverse effects produced worldwide for their products, and to present an annual assessment in Health Canada.They have to conduct phase 4 clinical trials, post -commercialization, to verify the efficiency and safety of their products from tens of thousands of people.From this data, the authorities may decide to ban a product or simply require that the information be updated in the monograph, the detailed "notice" provided to health professionals.

The immunization committees of Canada and Quebec also use all this vaccinovigilance information to recommend that the whole population or some people to use one vaccine rather than another, according to their efficiency and safety profile.Link

Je suis tombé(e) malade après avoir reçu le vaccin. Celui-ci est-il en cause ?Afficher la réponse

It could happen.You or your doctor must first declare this Canada Vigilance program disease.A whole process then sets in motion to check if the vaccine is really behind your condition.After all, people die or contract illnesses every day for all kinds of reasons, whether or not they have received a vaccine! To determine whether a vaccine can be responsible for a disease or a death that occurred shortly after,WHO and national authorities analyze epidemiological surveys and studies conducted as soon as vaccination began.This makes it possible to see if it increases the impact of certain health problems, by comparing the numbers of cases which occurred in people who have not received the vaccine and in those who have had it.Studies on the mode of operation of vaccines also assess the potential existence of a biological mechanism which would explain that this or that vaccine increases the risk of certain diseases.

It is for this reason, for example, that it is estimated that any case of Guillain-Barré syndrome which occurs in the month following the injection of a vaccine against influenza is probably caused by injection, even if wecannot be sure of it."It is the same principle of the preponderance of evidence as applied by justice," explains epidemiologist Gaston de Serres, of the National Institute of Public Health of Quebec (Inspq), who studies causality between vaccines and problemshealth.At the Canada Public Health Agency, the Causality Assessment Consultative Committee assesses the side effects according to vaccination to estimate the probability that they are caused by vaccines.

This analysis was carried out, for example, for invagination, an abnormal folding of the intestine which can affect babies after a vaccination against rotaviruses, the main responsible for gastroenteritis of infants."We must put the risk in perspective," insists the pediatrician-infectiologist Marc Lebel."The normal incidence of invagination in Quebec is 22 cases per 100,000 babies, and that due to the vaccine is 1 in 100,000 cases. Depuis que le premier vaccin contre le rotavirus a été autorisé, en 2006, on est passé de 225 bébés hospitalisés par an à Sainte-Justine à cause de ce virus à moins de 10 ! »Link

Ai-je des recours si les choses tournent mal ?Afficher la réponse

Quebec has been, since 1987, the only province to have a vaccination compensation program.Between 1988 and April 2020, 284 requests were filed.A committee made up of three doctors - one chosen by the Ministry of Health, one chosen by the patient or his relatives, and a third chosen by the first two - determines which are admissible and analyzes the possible causation between the vaccine and the damage suffered.During these 32 years, 53 people have been compensated for a total of $ 6.5 million, mainly for Guillain-Barré syndrome.Link