Clin Infect Dis. 2021 Apr 25:ciab345. doi: 10.1093/cid/ciab345. Online ahead of print.
BACKGROUND: A better understanding of re-infection after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has become one of the healthcare priorities in the current pandemic. We determined the rate of re-infection, associated factors and mortality during follow up in a cohort of patients with SARS-CoV-2 infection.
METHODS: We analyzed 9,119 patients with SARS-CoV-2 infection who received serial tests in total of 62 healthcare facilities in United States between December 1, 2019 to November 13, 2020. Re-infection was defined by two positive tests separated by interval of greater than 90 days two after resolution of first infection was confirmed by two or more consecutive negative tests. We performed logistic regression analysis to identify demographic and clinical characteristics associated with re-infection.
RESULTS: Re-infection was identified in 0.7% (n=63, 95% confidence interval [CI] 0.5%-0.9%) during follow up of 9,119 patients with SARS-CoV-2 infection. The mean period (±standard deviation [SD]) between two positive tests was 116 ± 21 days. A logistic regression analysis identified that asthma (odds ratio [OR] 1.9, 95% CI 1.1-3.2) and nicotine dependence/tobacco use (OR 2.7, 95% CI 1.6-4.5) were associated with re-infection. There was a significantly lower rate of pneumonia, heart failure, and acute kidney injury observed with re-infection compared with primary infection among the 63 patients with re-infection There were two deaths (3.2%) associated with re-infection.
CONCLUSIONS: We identified a low rate of re-infection confirmed by laboratory tests in a large cohort of patients with SARS-CoV-2 infection. Although re-infection appeared to be milder than primary infection, there was associated mortality.