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\begin{document}

\title{Enhanced immunity against to SARS-CoV-2 in returning ex-patriot Chinese}



\author[1]{Jiufeng  Sun}%
\author[1]{Runyu Yuan}%
\author[1]{Huimin Chen}%
\author[1]{Lina Yi}%
\author[1]{Xinxin Li}%
\author[1]{Ximing Hu}%
\author[1]{Xing Li}%
\author[1]{Huan Zhang}%
\author[1]{Pingping Zhou}%
\author[1]{Chumin Liang}%
\author[1]{Huifang Lin}%
\author[1]{Lilian Zeng}%
\author[1]{Xue Zhuang}%
\author[1]{QianQian Ruan}%
\author[1]{Yueling Chen}%
\author[1]{Yingyin Deng}%
\author[1]{Zhe Liu}%
\author[1]{Jing Lu}%
\author[1]{Jianpeng Xiao}%
\author[1]{Liang Chen}%
\author[2]{Xincai Xiao}%
\author[3]{Jing Li}%
\author[1]{Baisheng Li}%
\author[1]{Yan Li}%
\author[1]{Jianfeng He}%
\affil[1]{Guangdong Center for Disease Control and Prevention}%
\affil[2]{Guangzhou Medical University}%
\affil[3]{Sinovac Life Sciences Co Ltd}%


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  \date{May 25, 2024}


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\begin{abstract}
\textbf{Background} Global COVID-19 vaccination programs effectively
contain the fast spread of the SARS-CoV-2. Characteristic the immunity
status of returned populations will favor for understanding the
achievement of herd immunity and long-term management of COVID-19 in
China. \textbf{Methods} Returning travellers were recruited from 7
quarantine stations in Guangzhou, China. The immunity statuses of
participants were determined through Competitive ELISA,
Micro-Neutralization Assay and Enzyme-Linked FluoroSpot Assay.
\textbf{Results} A total of 272 subjects were involved in questionnaire
survey, in which 235 (86.4\%) were returning ex-patriot Chinese and 37
(13.6\%) were foreigners. Blood and throat swabs specimens were
collected from each of 108 returning ex-patriot Chinese. The
neutralizing antibody against SARS-CoV-2 was detected in
\textasciitilde{}90\% of returning ex-patriot Chinese, either in the
primary or the homologous and heterologous booster vaccination group.
The serum NAb titers of them were significantly decreased against
SARS-CoV-2 Omicron BA.5, BF.7, BQ.1 and XBB.1 compare with prototype
virus. However, memory T cell responses including specific IFN-\selectlanguage{greek}γ \selectlanguage{english}and
IL-2 were no differences in either group. Smoking, drinking, SARS-CoV-2
infection, COVID-19 vaccination, and the time interval between last
vaccination and the sampling were independent influencing factors for
NAb titers against prototype SARS-CoV-2 and variants of concerns. The
dose of vaccination was the unique common influencing factor for Omicron
variants. \textbf{Conclusions} The herd immunity was established in
returning ex-patriot Chinese who exposure to the complicated infection
and vaccination circumstance. Domestic residents will benefit from
booster of COVID-19 vaccines either in homologous and heterologous
vaccination after re-opening of China, as well as breakthrough
infection.%
\end{abstract}%



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\verb`Main Manuscript.docx`  available at \url{https://authorea.com/users/636671/articles/653439-enhanced-immunity-against-to-sars-cov-2-in-returning-ex-patriot-chinese}

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