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, and demographics data to profile participants who were reinfected with SARS-CoV-2, defined as having two reverse transcriptase-polymerase chain reaction-positive SARS-CoV-2 tests within at least 90 days apart. A multivariate logistic regression model assessed the risk factors associated with reinfection. Two control groups were selected: nonreinfected participants reporting a positive test (control group one) and those reporting a negative test (control group two). Results: Between March 2020 and December 2021, 4454 reinfected participants were identified in Saudi Arabia (0.8%, 95% confidence interval [CI] 0.7-0.8). The majority (67.3%) were unvaccinated (95% CI 65.9-68.7) and 0.8% (95% CI 0.6-1.1) 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, whereas it conferred 61% (odds ratio [OR] 0.4, 95% CI 0.1-1.0) additional protection against severe disease after the first dose and 100% after the second dose. In the risk factor analysis, reinfection was highly associated with comorbidities, such as HIV (OR 2.5, 95% CI 1.3-5.2; P = 0.009), obesity (OR 2.3, 95% CI 1.3-3.9; P = 0.003), pregnancy (OR 3.2, 95% CI 1.4-7.4; P = 0.005), and working in health care facilities (OR 6.1, 95% CI 3.1-12.9; P <0.0 001). The delta variant (B.1.617.2) was the most frequent variant of concern among the reinfected cohort. Conclusion: This in-depth study of the reinfection profile identified risk factors and highlighted the associated SARS-CoV-2 variants. Results showed that naturally 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. (c) 2022 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Automated summary

This retrospective national study in Saudi Arabia identified 4454 reinfection cases of SARS-CoV-2, accounting for 0.8% of the population. Most of the reinfections were among unvaccinated individuals, and a small percentage resulted in severe or fatal disease. The study also found that comorbidities, obesity, pregnancy, and working in healthcare facilities were strongly associated with reinfection. The Delta variant (B.1.617.2) was the most prevalent variant among the reinfection cases.