Trajectories of seroprevalence and neutralizing activity of antibodies against SARS-CoV-2 in southern Switzerland between July 2020 and July 2021: An ongoing, prospective population-based cohort study.

Amati, Rebecca and Piumatti, Giovanni and Franscella, Giovanni and Buttaroni, Peter and Camerini, Anne-Linda and Corna, Laurie and Levati, Sara and Fadda, Marta and Fiordelli, Maddalena and Annoni, Anna Maria and Bezani, Kleona and Amendola, Antonio and Fragoso Corti, Cristina and Sabatini, Serena and Kaufmann, Marco and Frei, Anja and Puhan, Milo Alan and Crivelli, Luca and Albanese, Emiliano (2022) Trajectories of seroprevalence and neutralizing activity of antibodies against SARS-CoV-2 in southern Switzerland between July 2020 and July 2021: An ongoing, prospective population-based cohort study. International Journal of Environment Research Public Health, 20 (4).

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Abstract

Objectives: The COVID-19 pandemic continues, and evidence on infection- and vaccine-induced immunity is key. We assessed COVID-19 immunity and the neutralizing antibody response to virus variants across age groups in the Swiss population. Study Design: We conducted a cohort study in representative community-dwelling residents aged five years or older in southern Switzerland (total population 353,343), and we collected blood samples in July 2020 (in adults only, N = 646), November–December 2020 (N = 1457), and June–July 2021 (N = 885). Methods: We used a previously validated Luminex assay to measure antibodies targeting the spike (S) and the nucleocapsid (N) proteins of the virus and a high-throughput cell-free neutralization assay optimized for multiple spike protein variants. We calculated seroprevalence with a Bayesian logistic regression model accounting for the population’s sociodemographic structure and the test performance, and we compared the neutralizing activity between vaccinated and convalescent participants across virus variants. Results: The overall seroprevalence was 7.8% (95% CI: 5.4–10.4) by July 2020 and 20.2% (16.4–24.4) by December 2020. By July 2021, the overall seroprevalence increased substantially to 72.5% (69.1–76.4), with the highest estimates of 95.6% (92.8–97.8) among older adults, who developed up to 10.3 more antibodies via vaccination than after infection compared to 3.7 times more in adults. The neutralizing activity was significantly higher for vaccine-induced than infection-induced antibodies for all virus variants (all p values < 0.037). Conclusions: Vaccination chiefly contributed to the reduction in immunonaive individuals, particularly those in older age groups. Our findings on the greater neutralizing activity of vaccine-induced antibodies than infection-induced antibodies are greatly informative for future vaccination campaigns.

Item Type:	Scientific journal article, Newspaper article or Magazine article
Subjects:	Social studies Social studies > Sociology
Department/unit:	Dipartimento economia aziendale, sanità e sociale > Centro competenze anziani
Depositing User:	Roberta Torriani
Date Deposited:	28 Feb 2023 05:41
Last Modified:	28 Feb 2023 05:44
URI:	http://repository.supsi.ch/id/eprint/13827

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