- 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
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.