Infectious Diseases and Therapy (Mar 2024)

Longitudinal Molecular and Serological Evidence of SARS-CoV-2 Infections and Vaccination Status: Community-Based Surveillance Study (CONTACT)

  • Olga Sánchez-Soliño,
  • Ryan D. Kilpatrick,
  • Christopher Johnson,
  • Yixin Fang,
  • Yizhou Ye,
  • Negar Niki Alami,
  • Katarzyna Zarish,
  • Whitney S. Krueger,
  • Nancy Dreyer,
  • Gregory C. Gray

DOI
https://doi.org/10.1007/s40121-024-00923-4
Journal volume & issue
Vol. 13, no. 4
pp. 633 – 645

Abstract

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Abstract Introduction This prospective, longitudinal, community-based study, EpidemiologiCal POpulatioN STudy of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Lake CounTy, Illinois (CONTACT), investigated coronavirus disease 2019 (COVID-19) immunity, occupational risks related to SARS-CoV-2 exposure, and long-term immunoglobulin G (IgG) seroconversion kinetics. Methods At baseline and follow up (3, 6, and 9 months), non-hospitalized adult participants provided nasal and blood serum specimens for molecular [reverse transcription polymerase chain reaction (RT-PCR)] and serological (IgG) testing (4 November 2020–30 October 2021). Results At baseline, 6.4% (65/1008) had evidence of current/prior SARS-CoV-2 infection. At 3, 6, and 9 months, positive PCR tests were obtained from 0.4% (3/781), 0.4% (3/733), and 0% (0/673) of participants, respectively. Positive IgG occurred at baseline and 3, 6, and 9 months in 4.5% (45/1008), 6.0% (48/799), 5.4% (39/733), and 2.8% (19/673) of participants, respectively. Of participants positive for IgG at baseline, 28 had a negative IgG test at a follow-up visit; of those 28, 21 had their first negative IgG test within 6 months. Participants were more likely to retain positive IgG if they were 18–29 years of age, were male, or had medium-high/high-risk occupations. A high vaccination rate (70% received ≥ 1 dose by 9 months) was observed. Influence of occupational status or characteristics on transmission and IgG, and COVID-19 vaccination trends, are shown. Conclusions This study expands on prior studies assessing COVID-19 immunity and IgG seroconversion by including both RT-PCR and serologic testing and longitudinal follow-up of study participants. We observed decreased infection rates over the 9 month follow-up period as well as a decline in IgG persistency after 6 months. The findings from this community-based study regarding vaccinate rates, infection rates by PCR, and IgG persistency over time can help improve our understanding of COVID-19 immunity, occupational risks related to SARS-CoV-2 exposure, and the kinetics of long-term IgG seroconversion, which is important to help guide local and national mitigation strategies. Clinical Trial Registration NCT04611230.

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