In January 2022, Marco Cavaleri, Head of Vaccines Strategy at the European Medicines Agency raised concerns about frequent COVID-19 booster shots, as these vaccines can potentially overload people’s immune systems and tire them out, eventually weakening their immune responses.
One month later, in February 2022, a Swedish total population cohort study was published in The Lancet. According to this study, the immunity of people who had received two doses of COVID-19 vaccines declined over time, and after eight months, their immune function against the virus was even lower than that of the unvaccinated individuals.
