Different anti-Covid vaccines, with reminders made at different times, which must guarantee coverage from contagion for periods of different duration. Aifa has authorized seven months of protection for all vaccines against Covid-19. On average seven months. But this is not the case in everyday practice. It happens that a person who was vaccinated in January with Pfizer, which until yesterday expected a booster at 21 days, has antibodies against the virus until September, while another, who did Astra Zeneca also in January, thanks to the second dose taken after three months, you can arrive in December still protected.