Persistence of anti-SARS-CoV-2 antibodies: heterogeneity of immunological tests and implications for serosurveillance

Perez-Saez J, Zaballa ME, Yerly S, Andrey DO, Meyer B, Eckerle I, Balavoine JF, Chappuis F, Pittet D , Trono D, Kherad O, Vuilleumier N, Kaiser L, Guessous I, Stringhini S, Azman AS on behalf of Specchio-COVID19 Study Group.
Persistence of anti-SARS-CoV-2 antibodies: immunoassay heterogeneity and implications for serosurveillance. Clinical Microbiology and Infection, 2021 Nov;27(11):1695.e7-1695.e12. doi: 10.1016/j.cmi.2021.06.040. Epub 2021 Jul 7.

Summary:

Aims: Serological studies have been essential to monitor the evolution of the COVID-19 pandemic. Data on the persistence of anti-SARS-CoV-2 antibodies remain scarce, particularly in infected individuals with few or no symptoms. The aim of the study was to quantify the sensitivity of three commercially available immunological tests for detecting past infection with SARS-CoV-2 as a function of time since infection. The implications of the decreasing sensitivity of the immunoassays for seroprevalence estimation were also explored.

Methods: We followed a cohort of individuals infected with asymptomatic SARS-CoV-2 (n=354) at least 8 months after their presumed date of infection. Testing for anti-SARS-CoV-2 antibodies was performed using three commercially available assays: Roche-N, Roche-RBD and EuroImmun-S1. We developed a latent class statistical model to deduce the specificity and sensitivity of each test and to show, through simulations, how inappropriate consideration of test performance can lead to biased serology estimates.

Results: Antibodies were detected during follow-up in 74 to 100% of participants, depending on the immunological tests. Both Roche tests maintained high sensitivity, with the EuroImmun test missing 40% of infections after 9 months. Simulations reveal that without appropriate adjustment for variations in test sensitivity over time, seroprevalence surveys may underestimate infection rates.

Discussion: Antibodies persist for at least 8 months after infection in a cohort of individuals infected with SARS-CoV-2, with antibody detection varying according to the choice of test. Appropriate adjustment of test performance is important for the interpretation of serological studies in the event of a decrease in sensitivity after infection.

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