COVID-19 Vaccination Reduced the Risk of Reinfection by Approximately 50%

A cohort study in JAMA Network Open analyzed the efficacy of the COVID-19 vaccine in preventing SARS-CoV-2 reinfection. The study found that COVID-19 vaccination reduced reinfection rates by approximately 50%.

Despite the common misconception that the COVID pandemic is a thing of the past, SARS-CoV-2 infections persist with the emergence of new variants posing a threat to public health.

The CDC COVID tracker estimates an average of 127,786 new covid cases daily. At the same time, public health officials and government organizations continue strategizing ways to minimize COVID risk.

Using data from the Rhode Island Department of Health from March 2020 to December 2021, investigators conducted a population-based cohort study. Researchers looked at individuals over the age of 12 and divided them into three populations: (1) residents of long-term congregate care (LTCC), (2) employees of LTCC, and (3) the general population.

They compared patients who had gotten COVID and were vaccinated to patients who had gotten COVID and were not vaccinated before or within 90 days of infection.

In the publication, clinicians state, “probability of reinfection within nine months of recovery from primary infection with SARS-CoV-2 was approximately 2% in the unvaccinated general population, but 10% in LTCC employees and 13% among LTCC residents.”

Furthermore, the researchers found that vaccine efficacy with the completed primary vaccine series was 49% for LTCC patients and employees and 62% for the general population.

Reducing the risk of reinfection may also reduce the likelihood of mortality and developing long covid or related symptoms such as heart damage.

While this study provides insight on how vaccination can minimize reinfection, the research timeframe does not allow us to extrapolate information on new variants such as BA.5 that have risen in prevalence in recent months.

Although the timeframe presents some limitations, the benefits of vaccination are corroborated by other studies. Medical professionals strongly urge vaccination for patients who have not yet received their primary vaccine series.

Moreover, those eligible to receive a booster are encouraged to do so. The Commonwealth Fund estimates that a fall booster campaign could prevent up to 160,000 deaths.

“Vaccination after recovery from COVID-19 was associated with substantial benefit, reducing the risk of reinfection by approximately half. Individuals who have recovered from COVID-19 and remain unvaccinated should be encouraged to complete vaccinations, as they are eligible, to reduce their risk of reinfection,” recommended the investigators in the publication.