COVID-19 vaccination after infection reduces reinfection risk by half: JAMA

The primary outcome was SARS-CoV-2 reinfection, which is defined as a positive polymerase chain reaction (PCR) or antigen test result obtained in the lab at least 90 days after the initial positive PCR or antigen test result.

The key findings of this study were as follows:

1. Overall, 94 516 people from the general community, 3124 LTCC residents, and 2877 LTCC staff were eligible.

2. The likelihood of reinfection for those who remained unvaccinated at 9 months after recovering from a prior COVID-19 infection was 10.0% for LTCC personnel, 13.0% for residents, and 1.9% for the general population.

3. After adapting for potential sociodemographic and clinical confounders as well as temporal variation in infection rates, fulfillment of the primary vaccination series after infection was associated with 49% protection among LTCC residents, and 47% protection among LTCC employees, and 62% protection in the general population against reinfection.

In conclusion, the results of this study indicate that the risk of reinfection among those who remained unvaccinated, including the general community as well as LTCC residents and personnel, was rather high after recovering from COVID-19. After recovering from COVID-19, vaccination was associated with significant benefits, cutting the chance of reinfection by around half. To lower their risk of reinfection, people who have recovered from COVID-19 but are still unvaccinated should be urged to finish their shots as soon as they are able.

Reference: 

Lewis, N., Chambers, L. C., Chu, H. T., Fortnam, T., De Vito, R., Gargano, L. M., Chan, P. A., McDonald, J., & Hogan, J. W. (2022). Effectiveness Associated With Vaccination After COVID-19 Recovery in Preventing Reinfection. In JAMA Network Open (Vol. 5, Issue 7, p. e2223917). American Medical Association (AMA). https://doi.org/10.1001/jamanetworkopen.2022.23917