PLoS ONE (Jan 2022)

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

  • Whitney E. Harrington,
  • Winnie Yeung,
  • Ingrid A. Beck,
  • Fred D. Mast,
  • John Houck,
  • Sheila Styrchak,
  • Leslie R. Miller,
  • Song Li,
  • Micaela Haglund,
  • Yonghou Jiang,
  • Blair Armistead,
  • Jackson Wallner,
  • Tina Nguyen,
  • Daisy Ko,
  • Samantha Hardy,
  • Alyssa Oldroyd,
  • Ana Gervassi,
  • John D. Aitchison,
  • Lisa M. Frenkel

Journal volume & issue
Vol. 17, no. 9

Abstract

Read online

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.