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Rapid Decay of Anti–SARS-CoV-2 Antibodies in Individuals With Mild COVID-19
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Recently published data suggest a rapid clearance of antibodies after recovery from SARS-CoV-2 infection. This article reports experience of 34 patients from the University of California in Los Angeles with confirmed COVID-19 whose serial antibody titers (ranging 44–119 days) were monitored. The researchers demonstrated an antibody half-life of 36 days over an observation period of approximately 90 days.
- With these data, it does not appear that durable humoral immunity is achieved after SARS-CoV-2 infection. These data need to be carefully considered as the world rushes to develop a vaccine and make public health policies for patients who are antibody-positive.
abstract
This abstract is available on the publisher's site.
Access this abstract nowA recent article suggested the rapid decay of anti–SARS-CoV-2 IgG in early infection, but the rate was not described in detail. We evaluated persons who had recovered from Covid-19 and referred themselves to our institution for observational research. Written informed consent was obtained from all the participants, with approval by the institutional review board. Blood samples were analyzed by enzyme-linked immunosorbent assay (ELISA) to detect anti–SARS-CoV-2 spike receptor-binding domain IgG. The ELISA was further modified to precisely quantify serum anti–receptor-binding domain activity in terms of equivalence to the concentration of a control anti–receptor-binding domain monoclonal IgG (CR3022, Creative Biolabs).
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Rapid Decay of Anti–SARS-CoV-2 Antibodies in Persons With Mild Covid-19
N. Engl. J. Med 2020 Jul 21;[EPub Ahead of Print], FJ Ibarrondo, JA Fulcher, D Goodman-Meza, J Elliott, C Hofmann, MA Hausner, KG Ferbas, NH Tobin, GM Aldrovandi, OO YangFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Rapid Decline on Anti–SARS-CoV-2 Antibodies
To appropriately confront the global pandemic of SARS-CoV-2, we need immunity. Immunity to pathogens, in general, can be achieved through infection and recovery, provision of convalescent sera (short term), cross-protection from a similar pathogen, or through vaccination. Accordingly, much attention centers on the antibody kinetics following natural infection and in response to vaccination.
In response to SARS-CoV-2, we focus on herd immunity thresholds. This is the somewhat magical proportion of the population needed to be currently immune to exert the herd effect, the point at which this virus will stop spreading. This threshold is related to the infectivity of a pathogen. The higher the infectivity, the higher the threshold. For SARS-CoV-2, the threshold is estimated to be 65% to 70%.1 In calculating our collective immunity, we add the naturally occurring immunity to that attained through immunization. That attained through immunization is dependent on the vaccine coverage rate and the vaccine effectiveness. Messing up the whole calculation, however, is waning of immunity, especially if this occurs over a short time window.
A recent study of a small cohort of naturally infected and recovered individuals sheds some light on durability of antibody for SARS-CoV-2.2 The 34 participants were middle-aged (mean, 43 years; range, 21–68 years) and most had mild COVID-19 illness. More importantly, they had more than one quantitative determination of anti–SARS-CoV-2 spike receptor-binding domain IgG. On average, the first level was obtained 37 days following the onset of illness; the last measurement occurred—on average—49 days after the first.
Of note was the relatively rapid decline of anti–SARS-CoV-2 antibody. The estimated half-life of decay was estimated to be approximately 36 days (95% CI, 26–60) over the observation period. As the authors state, “The protective role of antibodies against SARS-CoV-2 is unknown.” This rapid decline in persons with mild COVID-19, however, is concerning. Much work is needed to better understand the combined roles of humoral and tissue-mediated immunity for SARS-CoV-2 and the complex interplay among infection and recovery, immunization, and time.
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