(HealthDay)—Compared with primary infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), reinfections have 90 percent lower odds of severe, critical, or fatal disease based on data for the variants circulating during the study period, according to a letter to the editor published online Nov. 24 in the New England Journal of Medicine.
Noting that Qatar had two back-to-back waves of SARS-CoV-2 infections from January through May 2021, Laith J. Abu-Raddad, Ph.D., from Weill Cornell Medicine-Qatar in Doha, and colleagues examined the risk for severe disease, critical disease, and fatal disease caused by reinfections compared with primary infections in a national cohort of 353,326 persons with polymerase chain reaction-confirmed infection.
The researchers identified 1,304 reinfections, 31.7, 4.4, and 16.3 percent of which were caused by the beta and alpha variants and wild-type virus, respectively; 47.6 percent were of unknown status. The median time between first infection and reinfection was 277 days for reinfected persons. The odds of severe disease were 0.12-fold for reinfection versus primary infection. No cases of critical disease occurred at reinfection compared with 28 cases at primary infection (odds ratio, 0.00; 95 percent confidence interval, 0.00 to 0.64). No cases of death from COVID-19 occurred at reinfection compared with seven cases at primary infection (odds ratio, 0.00; 95 percent confidence interval, 0.00 to 2.57). For the composite outcome of severe, critical, or fatal disease, the odds at reinfection were 0.10 times that at primary infection.
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