тут к примеру Marco Cavaleri, the European Medicines Agency's head of vaccines strategy: frequent boosting could potentially have a negative impact on immune response to COVID-19, causing "fatigue in the population" that's received multiple shots

Cavaleri was likely referencing a concern that seeing antigens (like those provided by vaccines) over and over again can lead to T cell anergy or "exhaustion”, said Sarah Fortune, a professor at the Harvard TH Chan School of Public Health Department of Immunology and Infectious Diseases, in an email to DW.