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\begin{document}

\title{Do Quantitative Levels of Anti-Spike-IgG Antibodies Aid in Predicting
Protection from SARS-CoV-2 Infection? Results from a Longitudinal Study
in a Police Cohort}



\author[1]{Parham Sendi}%
\author[2]{Nadja Widmer}%
\author[3]{Mattia Branca}%
\author[4]{Marc Thierstein}%
\author[5]{Annina Elisabeth Büchi}%
\author[3]{Dominik Güntensperger}%
\author[5]{Manuel Raphael Blum}%
\author[1]{Rossella Baldan}%
\author[2]{Caroline Tinguely}%
\author[3]{Dik Heg}%
\author[6]{Elitza S. Theel}%
\author[7]{Elie Berbari}%
\author[7]{Aaron J Tande}%
\author[1]{Andrea Endimiani}%
\author[2]{Peter Gowland}%
\author[1]{Christoph Niederhauser}%
\affil[1]{Universitat Bern Institut fur Infektionskrankheiten}%
\affil[2]{Blutspende SRK Schweiz AG}%
\affil[3]{Universitat Bern}%
\affil[4]{Kantonspolizei Bern}%
\affil[5]{Insel Gruppe AG}%
\affil[6]{Mayo Clinic Division of Clinical Microbiology}%
\affil[7]{Mayo Clinic Division of Infectious Diseases}%


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  \date{May 24, 2024}


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\begin{abstract}
\textbf{Objectives} In a COVID-19 sero-surveillance cohort study with
predominantly healthy and vaccinated individuals, the objectives were
(i) to investigate longitudinally the factors associated with the
quantitative dynamics of anti-spike IgG antibody levels, (ii) to
evaluate whether the antibody levels were associated with protection
from SARS-CoV-2 infection and (iii) to assess whether the association
was different in the pre-Omicron compared with the Omicron period.
\textbf{Methods} The QuantiVac Euroimmun ELISA test was used to quantify
anti-S1 IgG levels. The entire study period (16 months), the 11-month
pre-Omicron period and the cross-sectional analysis prior to the Omicron
surge included 3219, 2310 and 895 reactive serum samples from 949, 919
and 895 study participants, respectively. Mixed-effect linear,
mixed-effect time-to-event and logistic regression models were used to
achieve the objectives. \textbf{Results} Age and time since infection or
vaccination were the only factors associated with a decline of anti-S1
IgG levels. Antibody levels were significantly associated with
protection from SARS-CoV-2 infection, and the association was higher for
the Omicron than for the Alpha and Delta variants. In a prediction
model, it was estimated that \textgreater{}8000 BAU/mL anti-S1 IgG was
required to reduce the risk of infection with Omicron variants by 20\%
to 30\% for 90 days. \textbf{Conclusions} Anti-S1 IgG antibody levels
are associated with protection from infection. The levels in the
pre-Omicron periods were less significant than during the Omicron surge,
which in turn required very high levels for protection in a statistical
model.%
\end{abstract}%



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\verb`PoliCoV-19 QuantiVaC Version 24032023.doc`  available at \url{https://authorea.com/users/600154/articles/631891-do-quantitative-levels-of-anti-spike-igg-antibodies-aid-in-predicting-protection-from-sars-cov-2-infection-results-from-a-longitudinal-study-in-a-police-cohort}

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