SARS-CoV-2 Seroprevalence and Profiles Among Convalescents in Sichuan Province, China.

Ling Zhou ,Ping Zhou,Juan Liu,Huiping Yang,Tao Huang,Deqiang Xian,Tao Zhang,Zhengdong Zhang,Jianxiang Tang,Yuanfang Zhu,Haozhou Wang,Chongkun Xiao,Jianan Xu,Wenwu Liu,Cheng Li,Ming Pan,Xiuwei Cheng,Xianping Wu,Xiao Chen,Xin Su ,Yuan Hu ,Hang Liao ,Xu Du ,Huanwen Peng

doi:10.3389/fpubh.2021.716483

Abstract

Objectives: To explore and understand the SARS-CoV-2 seroprevalence of convalescents, the association between antibody levels and demographic factors, and the seroepidemiology of convalescents of COVID-19 till March 2021.Methods: We recruited 517 voluntary COVID-19 convalescents in Sichuan Province and collected 1,707 serum samples till March 2021. Then we reported the seroprevalence and analyzed the associated factors.Results: Recent travel history was associated with IgM levels. Convalescents who had recent travel history were less likely to be IgM antibody negative [OR = 0.232, 95% CI: (0.128, 0.420)]. Asymptomatic cases had, approximately, twice the odds of being IgM antibody negative compared with symptomatic cases [OR = 2.583, 95% CI: (1.554, 4.293)]. Participants without symptoms were less likely to be IgG seronegative than those with symptoms [OR = 0.511, 95% CI: (0.293, 0.891)]. Convalescents aged 40–59 were less likely to be IgG seronegative than those aged below 20 [OR = 0.364, 95% CI: (0.138, 0.959)]. The duration of positive IgM antibodies persisted 365 days while the IgG persisted more than 399 days.Conclusions: Our findings suggested that recent travel history might be associated with the antibody levels of IgM, while age could be associated with the antibody levels of IgG. Infection type could be associated with both antibody levels of IgM and IgG that declined quicker in asymptomatic cases.

Highlights

The global pandemic of coronavirus disease 2019 (COVID19), an emerging infectious disease seeding from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed a serious threat to public health [1]
The majority of the COVID19 cases with positive immunoglobulin G (IgG) antibodies ranged from 20 years to 39 years old (210 cases), similar to those with positive immunoglobulin M (IgM) antibodies (59 cases)
Asymptomatic cases had approximately twice the odds of being IgM antibody negative compared with symptomatic cases [OR = 2.583, 95% CI: (1.554, 4.293), P < 0.001]

Summary

Introduction

The global pandemic of coronavirus disease 2019 (COVID19), an emerging infectious disease seeding from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed a serious threat to public health [1]. Antibody response is crucial in eliminating viral infection [3], and the seroprevalence of specific serum antibodies including immunoglobulin M (IgM) and immunoglobulin G (IgG) against SARS-CoV-2 can provide immune protection. Understanding the seroprevalence dynamic of SARS-CoV-2 assists in assessing the immunologic levels of convalescents and predicting the potential immune protection [4]. Previous studies have reported that specific IgM antibodies last only for 13 weeks in the body [7], while IgG antibodies are more longstanding with an average of 2 years [8]. Previous studies [10,11,12,13] have explored the seroprevalence of these antibodies from diversified perspectives, such as the accuracy of serological tests, immunological memory, and molecular findings. Associated factors and the duration of positive antibodies still require to be updated

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Conclusion