The most common real side effects for covid-19 vaccines are recorded before they are released

An article from Church Militant website has echoed an interview in which a man that self-identifies as Mike Yeadon, former employee at Pfizer, suggests to stop administering vaccines against covid-19 if their side effects are not known. This is a MISLEADING assertion: yes, it is impossible to predict how each body’s person will react to the vaccine individually, but the most common side effects are already known.

"Where is your medical ethics? Stop giving these experimental vaccines to people when you don't know what the side effects will be. Stop giving them to people who are not at risk of dying from the virus. Just stop! People are dying."

In order for a vaccine or by any other type of drug to be approved by the drug regulatory agencies, they must pass through three phases of clinical trials, which certify their safety and efficacy. The frequency of side effects are already observed in phase I, long before the efficacy of the injection is even analysed. 

Concerning vaccines against covid-19, it is known that the majority cause mild side effects as light fever and redness at the injection site. It is still early to know the more rare side effects, as these are often not detected until one moves from working with thousands of volunteers to working on a much larger scale and over a longer period of time. This post-approval surveillance phase is known as phase IV of the clinical trials.

The risk/benefit balance

The alleged physician has also highlighted that they should no longer be given “to people who are not at risk of dying due to the virus” since, as the side effects are not known, this could be counterproductive. Precisely one of the aspects that regulatory agencies such as the European Medicines Agency (EMA) take most into account is what they call the risk/benefit balance, i.e. whether the benefits of vaccination outweigh the risks involved in doing so: “In countries with several vaccination options, it can be considered to limit the use of AstraZeneca’s or Janssen’s vaccines, which have been associated with rare thrombosis cases”, to groups where the vaccine represents a higher benefit-risk, i.e. people aged 50 years and older," says Adelaida Sarukhan, immunologist and scientific writer at ISGlobal. These people have a much higher risk of hospitalisation or death from COVID and, "from what has been seen so far, a lower risk of developing this type of thrombus", she states. This is one of the reasons why AstraZeneca’s injection is not being recommended for under-30’s people in the UK, as with other vaccines available for this group, they do not consider it worthwhile to expose them to the risk of thrombosis, however rare this side effect may be. 

However, the benefit/risk computation also depends on the probability of infection: “In places with high incidence of cases, the vaccine provides much more benefits than risks, even in younger populations, points the immunologist.

On the other hand, it is important to remember that vaccination is not only a way to protect who is receiving the vaccine, but also the rest of the population. A recent study of The Centers for Disease Control and Prevention (CDC) indicates that Pfizer’s vaccine reduces transmission, also avoiding the development of severe disease. This means that vaccinating population groups that are not at a risk of dying is beneficial as a way of reducing transmission of the virus to other more vulnerable groups.