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Master of Public Health

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

AUTHORS

Self WH , Tenforde MW , Stubblefield WB , Feldstein LR , Steingrub JS , Shapiro NI , Ginde AA , Prekker ME , Brown SM , Peltan ID , Gong MN , Aboodi MS , Khan A , Exline MC , Files DC , Gibbs KW , Lindsell CJ , Rice TW , Jones ID , Halasa N , Talbot HK , Grijalva CG , Casey JD , Hager DN , Qadir N , Henning DJ , Coughlin MM , Schiffer J , Semenova V , Li H , Thornburg NJ , Patel MM , , , . MMWR. Morbidity and mortality weekly report. 2020 11 27; 69(47). 1762-1766

ABSTRACT

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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