Although the EMA and WHO caution regarding multiple boosters, there is no reasonable evidence that frequent boosters harm the immune system.
At a press conference on January 11, 2022, the European Medicines Agency (EMA) specialists stated that COVID-19 booster doses should not be administered at close intervals. At the briefing, Marco Cavaleri, the EMA's head of Biological Health Threats and Vaccines Strategy, said that the agency is concerned about the strategy that involves repeated vaccinations over a short period. According to Cavaleri, a booster dose should not be given every three or four months.
Cavaleri further commented that there might be an issue with the immunological response, and the immune response might not be good if boosters are given every four months. He says loading the immune system with vaccinations must be avoided.
On December 22, 2021, the World Health Organization (WHO) Director-General stated that "blanket booster measures are more likely to extend the pandemic than end it". Furthermore, in a statement issued on January 11, WHO Technical Advisory Group on COVID-19 Vaccine Composition said that "a vaccination strategy based on repeated booster doses of the original vaccine composition is unlikely to be appropriate or sustainable."
To cope with emerging COVID-19 variants, WHO experts proposed developing new vaccines to prevent people from becoming severely ill and avoid contracting the virus. The experts advised, "COVID-19 vaccines that have high impact on the prevention of infection and transmission, in addition to the prevention of severe disease and death, are needed and should be developed." In addition, the vaccines need to be more effective to prevent "Community transmission and the need for stringent and broad-reaching public health and social measures."
A preliminary study conducted by Israeli experts suggests a fourth COVID-19 shot does not appear to produce enough antibodies to prevent infection by the Omicron variant. Nevertheless, no evidence indicates that repeated boosters may have a harmful influence on the immune system in the general population. Hence, we consider this assertion to be unverifiable.