Risk Factors of SARS-CoV-2 and Follow-up in Patients with Common Underlying Diseases on the Dynamic Changes of Antibodies: A Cross-sectional Study

Abstract

Background: Assessing the humoral immunity of patients with underlying diseases after being infected with SARS-CoV-2 is essential for determining effective prevention and control strategies. The purpose of this study is to investigate whether underlying disease is a risk factor for SARS-CoV-2 infection, reveal the seroprevalence of people with underlying disease and the characteristics of dynamic changes in anti-SARS-CoV-2 antibodies, and provide evidence for the scientific formulation of COVID-19 vaccination strategies.Methods: The probability ratio sampling method was adopted to systematically select 100 communities from 13 districts in Wuhan, China, followed by a random selection of households from 100 communities according to a list provided by the local government. Individuals who have lived in Wuhan for at least 14 days since December 2019 and were ≥40 years old were included. Individuals with other serious diseases besides COVID-19, from whom a sample could not be obtained or refused to participate, were excluded. All eligible subjects signed a written informed consent form and completed a standardized electronic questionnaire before being enrolled in the group. From April 9–13, 2020, venous blood samples were collected from all individuals; from June 11–13, 2020, and from October 9–December 5, 2020, all positive and matched negative families were followed up.Results: The seroprevalence of SARS-CoV-2 in people with underlying diseases was 6.30% (95% CI [5.09-7.52]), and that of people without underlying diseases was 6.12% (95% CI [5.33-6.91]). Among people with underlying diseases, retirees, health workers, and people who have been exposed to fever or respiratory symptoms since December 2019 were more likely to be infected with SARS-CoV-2. The IgG titer of people with underlying disease decreased significantly over time (P <0.05), but the neutralizing antibody titer remained relatively stable throughout the follow-up period. There was no significant difference between the IgG titer decline rate of people with underlying disease and those without. The IgG titer of people with underlying disease and asymptomatic infection was lower than that in symptomatic infection.Conclusion: These findings imply that vaccination strategies for people with and without underlying diseases may not require special adjustments.