Prior COVID-19 infection was associated with a significantly decreased risk for recurrent infection among unvaccinated, according to findings from a cohort study published in JAMA Network Open.

Between October 2020 and November 2021, investigators obtained data from patients who were not vaccinated against COVID-19 infection and had symptoms suggestive of infection. All patients were evaluated for SARS-CoV-2 infection via nucleic acid amplification testing (NAAT) at baseline and were subsequently monitored for recurrent infection at 90 days. Using Cox proportional hazard regression, investigators compared the rate of COVID-19-free survival among patients who tested positive vs those who tested negative (controls) for infection, with adjustments made for age, sex, and race/ethnicity

At baseline, a total of 24,043 patients were positive for COVID-19 infection and 97,572 were negative. Of patients with COVID-19 infection at baseline, the mean age was 42.0 years, 55.1% were women, and 49.9% were White.


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Among patients with positive and negative NAAT results, 0.4% and 2.8% developed COVID-19 infection, respectively. Of patients who tested positive at baseline, the risk for recurrent infection was significantly decreased (hazard ratio, 0.15; 95% CI, 0.13-0.18). Further analysis showed that prior COVID-19 infection was associated with an 85% decreased risk for recurrent infection up to 9 months. 

This study was limited by the possibility that the behavior of patients who recovered from a previous COVID-19 infection differed compared with those without immunity from a prior infection.

“The findings of this study may have important implications for vaccine policy and public health,” the investigators concluded.

Reference

Ridgway JP, Tideman S, Wright B, Robicsek A. Rates of COVID-19 among unvaccinated adults with prior COVID-19. JAMA Netw Open. Published online February 24, 2022. doi:10.1001/jamanetworkopen.2022.7650