According to two new studies published in the New England Journal of Medicine, the Pfizer/BioNTech COVID-19 vaccine provides additional protection against reinfection for people who have already been infected with COVID-19, and that it provides increased immune persistence over time.

One study, conducted in Israel, noted that among people who had recovered from COVID-19, reinfections were more common (over four-fold) in individuals who did not get vaccinated compared to those who got vaccinated after the infection. However, the effectiveness of the Pfizer vaccine was found to be lower in adults aged above 65 years in the study. The vaccine had an 82% effectiveness among people aged 16 to 64 years compared to only 60% in those aged 65 and above. 

The second study, conducted in the United Kingdom, noted that immunity lasts longer in people who have recovered from COVID-19 infection prior to receiving a Pfizer vaccine. Among people who were not previously infected, two doses of the vaccine were tied to an 85% decline in risk of infection after two months of vaccination. The figure declined to 51% six months following vaccination. However, people who were vaccinated after recovering from COVID-19 were noted to have over 90% protection more than a year after the infection and more than six months after vaccination… (CNN, February 16, 2022)