According to the latest report from Public Health France, 21.133.653 French people have received at least one dose of vaccine. Among these doses administered, the National Medicines Agency identifies nearly 34.000 cases of adverse effects. But which are the most common? are they worrying or dangerous? We take stock.

According to the Ministry of Solidarity and Health, “An undesirable effect is a harmful and unwanted reaction to a drug when used in accordance with the terms of its marketing authorization or during any other use (overdose, misuse, abuse of drugs, medication error)“.

An undesirable effect (or side effect) is said to be serious:

• when it causes death or is likely to endanger the life of the vaccinee
• when it results in a form of disability or a significant or lasting incapacity
• when it causes or prolongs hospitalization
• when it manifests itself through an anomaly or malformation

Faced with the vaccine, our immune system reacts, it is also very likely that the vaccinated will react differently. As with all medicines, these treatments can cause side effects. Moreover, several hundred million people are vaccinated each year around the world and not only against Covid. After administration of a dose you may feel feverish, with mild pain or redness at the injection site.

Usually the unpleasant (but not dangerous) effects are: arm pain, body aches, nausea, vomiting, chills and headache. These symptoms can last for a few days. The majority of side effects are not serious.

It is normal to relieve headaches or pain at the injection site. According to the U.S. Centers for Disease Control and Prevention, it is recommended that you apply ice or a very cool washcloth to the area where you experience pain. In addition, the National Agency for the Safety of Medicines and Health Products recommends taking paracetamol “At the lowest dose and for the shortest time possible” to manage fever and pain.

However, under the advice of Dr Mathieu Calafiore, general practitioner, interviewed during the program “Allô Docteurs” on France 5, it is strongly discouraged to consume anti-inflammatory drugs because these drugs would decrease the reaction of the vaccine and make them less effective. .

Some side effects may be more intense, last longer, or appear later after vaccination. According to the Ministry of Solidarity and Health “If you experience any serious and / or unexpected side effect (s): you should immediately contact your doctor or another doctor or report it to your pharmacist. They will tell you what to do and do what is necessary for your health and the management of these side effects ”.

It is also recommended to report any side effects, in particular when they are serious. Identifying them can help advance vaccine safety. To report an adverse event, simply go to this dedicated portal: signalement-sante.gouv.fr

In its last checkpoint on the surveillance of vaccines against Covid-19, published on May 17, 2021, the National Agency for the Safety of Medicines and Health Products (Ansm) is reassuring. The side effects do exist, however the majority of them are harmless and “Not serious. “

For the Pfizer-BioNTech vaccine:

We can read in the synthesis of Ansm “Since the start of vaccination, 18 cases of adverse effects have been analyzed by the CRPV reporters (Bordeaux and Marseille). The majority of side effects are expected and not serious ”.

For the Moderna vaccine:

We can read “Since the start of vaccination, 1 cases of adverse effects have been analyzed by the CRPV reporters (Lille and Besançon). A large number of cases concern delayed local reactions that are not serious ”.

For the AstraZeneca vaccine:

“Since the start of vaccination with the Vaxzevria vaccine, 14 cases of adverse effects have been analyzed by the CRPV reporters (Amiens and Rouen). The vast majority of these cases concern flu-like syndromes, often of high intensity (high fever, body aches, headaches) “. During this period (April 23 to May 6), four new cases of thrombosis were reported. In total, 34 French people since the start of the vaccination campaign and eleven deaths are to be deplored. However, these cases are very rare. The Haute Autorité de santé recommends this vaccine for people aged 55 and over.

It is true that the second dose may cause more side effects than the first. According to a report published on December 31 by the New England Journal of Medicine (NEJM), 47% of 16-55 year olds said they felt tired after the first dose and 59% after the second injection. For head pain, we went from 32% to 42% respectively. Those vaccinated also reported more chills. We then went from 14 to 35% between the first and second injection. Asked by France Info, the doctor of immunology, Christian de Tymowski explains why the side effects can be more important after the second dose.

“When we receive the first dose, it takes a lag time to identify the particle and recognize it as a foreign particle, against which our immune system must defend itself. Conversely, during the second injection, the viral particle is immediately identified and the immune reaction is then more important. This is why we inject two doses: during the first, we will obtain a certain immunity which will not necessarily be very strong, but with the second, we warn the immune system by saying: “Look, it is really a dangerous particle, you have to plan a good response against it. “

It is not impossible to contract the virus (again) after the injection of the two doses. This is not, moreover, scientifically abnormal. The vaccines currently available in France are not 100% effective. For example, the Moderna vaccine is 95% effective against severe forms of Covid-19. According to a study, published in The New England Journal of Medicine on May 6, 2021, the positivity rate after vaccination is between 0,97 and 1,19%. The study also specifies that on average a Moderna vaccine protects in 14 days after the second injection against severe forms of the disease and 7 days for the Pfizer-BioNTech vaccine.

Vaccines are obviously used to prevent severe forms of the disease. With the help of vaccines, it is possible to slow down the pandemic by further stopping hospitalizations or even long forms of Covid.