The director of the Vaccine Strategy of the European Medicines Agency (EMA), Marco Cavaleri, told a press conference on 11 January that "it is not sustainable in the long term to continue giving booster doses every three or four months [to the general population]". Spanish immunologists agree that this is not the right thing to do. In these reactions they explain why.
Health workers prepare a vaccine against the coronavirus. / EFE/Doménech Castelló / POOL.
President of the Spanish Society of Immunology (SEI) and former secretary of the Spanish Society of Transplantation (SET)
The repeated booster strategy does not seem to make much sense at the present time. Repeating a booster with the same preparation of the original vaccine against the original Wuhan virus does not seem to make much sense if we want to induce neutralising antibodies against the new variants. They should include at least some of the variants such as delta or omicron. In any case, the T-cell response that protects us has already been induced and no new booster is needed for the memory T-cell part. In addition, the booster should ideally stimulate the response against other components of the virus and not necessarily against the S protein. The strategy of booster every few months does not seem to be of value. There is also no evidence that it is harmful, although there is no clear evidence on this either.
A strategy based on boosters every few months does not make sense, nor is it recommended. The immune system can become exhausted, exhausted, and achieve the opposite effect against the same vaccine. Many repeated immunisations over time induce tolerance, lower response, and have also been shown to affect the quality of antibodies. In addition, there could be problems due to an excess of antibodies. This is not yet known with this vaccine. The clinical trial in Israel with 4 doses will give valuable information on this.
There is no point in a strategy based on boosters every few months, mainly because it brings little in comparison to full vaccination. For Omicron it is very little. And not at all as long as these "third doses" lead us to forget what is really important: VACCINATE THE ENTIRE WORLD POPULATION.
As a generalised strategy for the whole population, a strategy based on boosters every few months is nonsense from an immunological point of view. As a strategy for vulnerable groups it may make sense, but it would be highly advisable to update the vaccine to the omicron variant and focus the booster only on this population group and with close monitoring of the loss of vaccine effectiveness. I very much miss studies of cell-mediated immunity + Ac, in this vulnerable group of patients in whom we need to know at what point they lose protection against the virus.
However, I doubt that giving boosters every few months is harmful. Our immune system is prepared to respond to a multitude of stimuli at the same time. But the secondary reactions to vaccination (adenopathies for example) would multiply, as would reactogenicity to the vaccine, discomfort, etc. Repeated boosters in the general population would only lead to a massive rejection of vaccination, and we would turn the success of the vaccination programme (in our country) into a failure due to the senseless abuse of vaccines.