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The promise of several effective vaccine candidates amidst a worldwide resurgence of COVID-19 renders urgent the need for information about the protection afforded by and durability of SARS-CoV-2 antibodies after natural infection or vaccination. Using data from a network of academic medical centers in 12 U.S. states, researchers sought such information. The member hospitals in the network collected convenience baseline blood samples from 3248 frontline healthcare workers between April and June 2020.
Overall, 6% (194) of participants had detectable antibodies to SARS-CoV-2 at baseline. Among these, 156 (80.4%) returned for the follow-up visit at a mean 60 days after the baseline test. Information on demographics, underlying conditions and COVID-compatible symptoms were collected at both visits. Among participants with initial antibodies who returned for a second test, 94% showed a decline in antibody levels and 28% had seroreversion to undetectable levels. Antibody levels measured by the second test were highest in those who had been symptomatic and who had the highest baseline levels. Older age and a previously negative antibody test, done before the baseline test, also correlated with greater decline in antibody level.
Self WH et al. Decline in SARS-CoV-2 antibodies after mild infection among frontline health care personnel in a multistate hospital network — 12 States, April–August 2020. MMWR Morb Mortal Wkly Rep 2020 Nov 27; 69:1762. (https://doi.org/10.15585/mmwr.mm6947a2)
Comment
This study contributes to the current uncertainty as to durability of the antibody response to SARS-CoV-2 (NEJM JW Infect Dis Oct 2020 and N Engl J Med 2020; 383:1085), although the limited available data indicate that the immune response may be protective (NEJM JW Infect Dis Nov 2020 and J Clin Microbiol 2020; 58:02107). An unsettling finding in this current report is the high percentage of participants who had seroreversion to undetectable antibody status. Whether this seroreversion will permit reinfection remains unclear. However, what is clear is that an antibody test performed more than 2 to 3 months after infection may falsely imply that the patient did not have infection with SARS-CoV-2. The implications of this “false negative” result are manifold.