Risk for Reinfection After SARS-CoV-2: A Living, Rapid Review for American College of Physicians Practice Points on the Role of the Antibody Response in Conferring Immunity Following SARS-CoV-2 Infection

Background: The strength and duration of immunity from infection with SARS-CoV-2 are important for public health plan-ning and clinical practice. Purpose: To synthesize evidence on protection against rein-fection after SARS-CoV-2 infection. Data Sources: MEDLINE (Ovid), the World Health Organization global literature database, ClinicalTrials.gov, COVID19reviews.org, and reference lists. Study Selection: Longitudinal studies that compared the risk for reinfection after SARS-CoV-2 infection versus infec-tion risk in individuals with no prior infection. Data Extraction: Two investigators sequentially extracted study data and rated quality. Data Synthesis: Across 18 eligible studies, reinfection risk ranged from 0% to 2.2%. In persons with recent SARS-CoV-2 infection compared with unvaccinated, previously uninfected individuals, 80% to 98% of symptomatic infections with wild-type or Alpha variants were prevented (high strength of evi-dence). In the meta-analysis, previous infection reduced risk for reinfection by 87% (95% CI, 84% to 90%), equaling 4.3 fewer infections per 100 persons in both the general population (risk difference,-0.043 [CI,-0.071 to-0.015]) and health care workers (risk difference,-0.043 [CI,-0.069 to-0.016]), and 26.6 fewer infections per 100 persons in care facilities (risk dif-ference,-0.266 [CI,-0.449 to-0.083]). Protection remained above 80% for at least 7 months, but no study followed patients after the emergence of the Delta or Omicron variant. Results for the elderly were conflicting. Limitation: Methods to ascertain and diagnose infections varied. Conclusion: Before the emergence of the Delta and Omicron variants, persons with recent infection had strong protection against symptomatic reinfections for 7 months compared with unvacci-nated, previously uninfected individuals. Protection in immunocom-promised persons, racial and ethnic subgroups, and asymptomatic index case patients is unclear. The durability of protection in the setting of the Delta and Omicron variants is unknown.