Low rate of SARS-CoV-2 incident infection identified by weekly screening PCR in a prospective year-long cohort study

• Published in: PloS one Vol. 17; no. 9; p. e0274078
• Main Authors: Harrington, Whitney E, Yeung, Winnie, Beck, Ingrid A, Mast, Fred D, Houck, John, Styrchak, Sheila, Miller, Leslie R, Li, Song, Haglund, Micaela, Jiang, Yonghou, Armistead, Blair, Wallner, Jackson, Nguyen, Tina, Ko, Daisy, Hardy, Samantha, Oldroyd, Alyssa, Gervassi, Ana, Aitchison, John D, Frenkel, Lisa M
• Format: Journal Article
• Language: English
• Published: San Francisco Public Library of Science 26-09-2022; Public Library of Science (PLoS)
• Subjects: Age; Antibodies; Asymptomatic; Biology and Life Sciences; Cohort analysis; Disease transmission; Enrollments; Health risks; Households; Identification methods; Immunization; Infections; Laboratories; Medicine and Health Sciences; People and Places; Polymerase chain reaction; Prevention; Risk factors; Screening; Severe acute respiratory syndrome; Severe acute respiratory syndrome coronavirus 2; Social distancing; Testing; Vaccines; United States; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0274078

Background Asymptomatic and pre-symptomatic SARS-CoV-2 infections may contribute to ongoing community transmission, however, the benefit of routine screening of asymptomatic individuals in low-risk populations is unclear. Methods To identify SARS-CoV-2 infections 553 seronegative individuals were prospectively followed for 52 weeks. From 4/2020-7/2021, participants submitted weekly self-collected nasal swabs for rtPCR and completed symptom and exposure surveys. Results Incident SARS2-CoV-2 infections were identified in 9/553 (1.6%) participants. Comparisons of SARS2-CoV-2(+) to SARS2-CoV-2(-) participants revealed significantly more close contacts outside the household (median: 5 versus 3; p = 0.005). The incidence of infection was higher among unvaccinated/partially vaccinated than among fully vaccinated participants (9/7,679 versus 0/6,845 person-weeks; p = 0.004). At notification of positive test result, eight cases were symptomatic and one pre-symptomatic. Conclusions These data suggest that weekly SARS2-CoV2 surveillance by rtPCR did not efficiently detect pre-symptomatic infections in unvaccinated participants.