SARS-CoV-2 Reinfection Rate and Outcomes in Saudi Arabia: A National Retrospective Study

Background: The characterization of reinfection with SARS-CoV-2 has been a subject of concern and controversy, especially with the surge of infections with highly transmissible variants worldwide.Methods: This retrospective national study used comorbidities, vaccination status, SARS-CoV-2 variants of concern (VOC), and demographics data to profile SARS-CoV-2 reinfected participants, defined as having two RT-PCR positive SARS-CoV-2 tests within at least 90 days apart. A multivariate logistic regression model assessed the risk factors of reinfected cases. Two control groups were selected: non-reinfected participants reporting a positive test (control group one) and reporting a negative test (control group two).Findings: Between March 2020 and December 2021, 4,454 reinfected participants were identified in Saudi Arabia (0·81%, 95% CI 0·79–0·83). The majority (67·3%) were unvaccinated (95% CI 65·9–68·7) and 0·8% (95% CI 0·57–1·09) had severe or fatal SARS-CoV-2 disease. COVID-19 vaccines were 100% effective against mortality in reinfected individuals who received at least one dose while it conferred 61% (odds ratio [OR] 0·39, 95% CI 0·15–1·03) additional protection against severe disease post first dose and 100% post second dose. In the risk factor analysis, reinfection was highly associated with comorbidities such as HIV (OR 2·5, 95% CI 1·29–5·18; p=0·009), obesity (OR 2·26, 95% CI 1·33–3·93; p=0·003), pregnancy (OR 3·17, 95% CI 1·45–7·42; p=0·005), and working in healthcare (OR 6·12, 95% CI 3·14–12·92; p<0·0001). The delta variant (B.1.617.2) was the most frequent VOC among the reinfected cohort.Interpretation: This in-depth study of reinfection profile identified risk factors and highlighted the associated SARS-CoV-2 variants. Results showed that natural-acquired immunity to SARS-CoV-2 through multiple reinfections together with vaccine-induced immunity provided substantial protection against severe SARS-CoV-2 disease and mortality.Funding: Saudi Ministry of Health (MOH).Declaration of Interests: The authors declare no conflicts of interest.Ethics Approval Statement: This retrospective study was approved by the Institutional Review Board (IRB) committee from the Saudi MOH (IRB Log No. 21-111 M) with a waiver of informed consent.