It is important to understand the cognition, willingness, and psychological anxiety state of Chinese guardians toward COVID-19 vaccination for their children to predict the future vaccination rate and to help the design of policies that aim to expand the population with immunity against COVID-19. This study collected data with a professional vaccination registration platform for children named "Xiao Dou Miao" in February 2021. The psychological anxiety state of the guardians was self-evaluated using the psychological anxiety scale. Factors that might influence the willingness of guardians to vaccinate their children were identified using logistic regression analysis. This study included 12,872 questionnaires with 70.9% of guardians showing willingness to vaccinate their children. Guardians who were male, aged 40-49 and from rural area were more willing to vaccinate their children. Fathers, guardians with higher education and income, whose children have a history of adverse vaccine reactions and allergies were less willing to vaccinate their children (p < .001). More than 80% of the guardians expressed a high level of trust for vaccine information released by official and health-related agencies. Guardians who were not vaccinated were more anxious than those who were vaccinated (χ2 = 27.99, p < .001). To protect children from COVID-19, vaccine coverage in children should be expanded rapidly and public awareness on vaccine safety and effectiveness should be improved.

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Background Assessing the humoral immunity of patients with underlying diseases after being infected with SARS-CoV-2 is essential for adopting effective prevention and control strategies. The purpose of this study is to analyze the seroprevalence of people with underlying diseases and the dynamic change features of anti-SARS-CoV-2 antibodies. Methods We selected 100 communities in Wuhan using the probability-proportional-to-size sampling method. From these 100 communities, we randomly selected households 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. From April 9–13, 2020, community staff invited all selected individuals to the community healthcare center in batches by going door-to-door or telephone. All participants completed a standardized electronic questionnaire simultaneously. Finally, 5 ml of venous blood was collected from all participants. Blood samples were tested for the presence of pan-immunoglobulins, IgM, IgA, and IgG antibodies against SARS-CoV-2 nucleocapsid protein and neutralising antibodies were assessed. During the period June 11–13, 2020 and October 9–December 5, 2020, all family members of a positive family and matched negative families were followed up twice. Results The seroprevalence of anti-SARS-CoV-2 antibodies 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]). A total of 313 people were positive for total antibodies at baseline, of which 97 had underlying disease. At the first follow-up, a total of 212 people were positive for total antibodies, of which 66 had underlying disease. At the second follow-up, a total of 238 people were positive for total antibodies, of which 68 had underlying disease. A total of 219 participants had three consecutive serum samples with positive total antibodies at baseline. The IgG titers decreased significantly with or without underlying diseases (P < 0.05) within the 9 months at least, while the neutralizing antibody titer remained stable. The titer of asymptomatic patients was lower than that of symptomatic patients (baseline, P = 0.032, second follow-up, P = 0.018) in the underlying diseases group. Conclusion Our research focused on the serological changes of people with and without underlying diseases in a state of single natural infection. Regardless of the underlying diseases, the IgG titer decreased significantly over time, while there was no significant difference in the decline rate of IgG between with and without underlying diseases. Moreover, the neutralizing antibody titer remained relatively stable within the 9 months at least.

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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.