Effectiveness of COVID-19 vaccination in preventing reinfection

Editor's Note

This study by researchers from Brown University, Providence, Rhode Island, finds that completing a primary vaccination series after recovering from COVID-19 reduces the risk of reinfection by about half.

A total of 95,000 Rhode Island residents participated in this cohort study, including residents and employees of long-term congregate care (LTCC) facilities.

Completion of the primary vaccination series after recovering from COVID-19 was associated with:

• 49% protection from reinfection in LTTC residents
• 47% protection from reinfection in LTTC employees
• 62% protection from reinfection in the general population during periods when Alpha and Delta strains were predominant.

Probability of reinfection at 9 months for those who remained unvaccinated after recovering from COVID-19 was:

• 13% in LTCC residents
• 10% in LTCC employees
• 1.9% in the general population.

Those who have recovered from COVID-19 and remain unvaccinated should be encouraged to complete vaccinations and reduce their risk of reinfection, the researchers conclude.