Nationwide study of rates of reinfection with SARS-CoV-2 among adults in Kuwait.

Abstract

Data are scarce on differences in the rates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection after the first infection. We examined nationwide data on SARS-CoV-2 reinfection in Kuwait according to four-time windows to reinfection: 29-45 days, 46-60 days, 61-90 days, and ≥ 91 days. This was a population-level retrospective cohort study conducted between 31 March 2020 and 31 March 2021. We reviewed evidence of second positive RT-PCR test results for those who had previously recovered from COVID-19 and tested negative. Reinfection rates were: 0.52% for reinfection window 29-45 days, 0.36% for 45-60 days, 0.29% for 61-90 days, and 0.20% for ≥ 91 days. The mean age (standard deviation [SD]) of individuals with the shortest reinfection time interval (29-45 days) was significantly older than the mean age of all other groups - 43.3 years (SD 17.5) compared with: 39.0 years (SD 16.5), P = 0.037 for 46-60-day interval; 38.3 years (SD 16.5), P = 0.002 for 61-90-day interval; and 39.2 years (SD 14.4), P = 0.001 for ≥ 91-days interval. SARS-CoV-2 reinfection was uncommon among this adult population. Older age was associated with a shorter time to reinfection.