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Decline in SARS-CoV-2 Antibodies After Mild Infection Among Frontline Health Care Personnel in a Multistate Hospital Network - 12 States, April-August 2020.

  • Author(s): Self, Wesley H;
  • Tenforde, Mark W;
  • Stubblefield, William B;
  • Feldstein, Leora R;
  • Steingrub, Jay S;
  • Shapiro, Nathan I;
  • Ginde, Adit A;
  • Prekker, Matthew E;
  • Brown, Samuel M;
  • Peltan, Ithan D;
  • Gong, Michelle N;
  • Aboodi, Michael S;
  • Khan, Akram;
  • Exline, Matthew C;
  • Files, D Clark;
  • Gibbs, Kevin W;
  • Lindsell, Christopher J;
  • Rice, Todd W;
  • Jones, Ian D;
  • Halasa, Natasha;
  • Talbot, H Keipp;
  • Grijalva, Carlos G;
  • Casey, Jonathan D;
  • Hager, David N;
  • Qadir, Nida;
  • Henning, Daniel J;
  • Coughlin, Melissa M;
  • Schiffer, Jarad;
  • Semenova, Vera;
  • Li, Han;
  • Thornburg, Natalie J;
  • Patel, Manish M;
  • CDC COVID-19 Response Team;
  • IVY Network
  • et al.

Most persons infected with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), develop virus-specific antibodies within several weeks, but antibody titers might decline over time. Understanding the timeline of antibody decline is important for interpreting SARS-CoV-2 serology results. Serum specimens were collected from a convenience sample of frontline health care personnel at 13 hospitals and tested for antibodies to SARS-CoV-2 during April 3-June 19, 2020, and again approximately 60 days later to assess this timeline. The percentage of participants who experienced seroreversion, defined as an antibody signal-to-threshold ratio >1.0 at baseline and <1.0 at the follow-up visit, was assessed. Overall, 194 (6.0%) of 3,248 participants had detectable antibodies to SARS-CoV-2 at baseline (1). Upon repeat testing approximately 60 days later (range = 50-91 days), 146 (93.6%) of 156 participants experienced a decline in antibody response indicated by a lower signal-to-threshold ratio at the follow-up visit, compared with the baseline visit, and 44 (28.2%) experienced seroreversion. Participants with higher initial antibody responses were more likely to have antibodies detected at the follow-up test than were those who had a lower initial antibody response. Whether decay in these antibodies increases risk for reinfection and disease remains unanswered. However, these results suggest that serology testing at a single time point is likely to underestimate the number of persons with previous SARS-CoV-2 infection, and a negative serologic test result might not reliably exclude prior infection.

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