Abstract
The appearance and magnitude of the immune response and the related factors correlated with SARS-CoV-2 vaccination need to be defined. Here, we enrolled a prospective cohort of 52 participants who received two doses of inactivated vaccines (BBIBP-CorV). Their serial plasma samples (n = 260) over 2 months were collected at five timepoints. We measured antibody responses (NAb, S-IgG and S-IgM) and routine blood parameter. NAb seroconversion occurred in 90.7% of vaccinated individuals and four typical NAb kinetic curves were observed. All of the participants who seroconverted after the first dose were females and had relatively high prevaccine estradiol levels. Moreover, those without seroconversion tended to have lower lymphocyte counts and higher serum SAA levels than those who experienced seroconversion. The NAb titers in young vaccine recipients had a significantly higher peak than those in elderly recipients. S-IgG and S-IgM dynamics were accompanied by similar trends in NAb. Here, we gained insight into the dynamic changes in NAbs and preliminarily explored the prevaccine blood parameters related to the kinetic subclasses, providing a reference for vaccination strategies.
Highlights
As of May 29th, 2021, there have been more than 170 million worldwide confirmed cases of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the pandemic has caused more than 5.1 million deaths
neutralizing antibodies (NAbs) were negative at the prevaccine baseline, and 90.7% of the vaccine recipients seroconverted after the administration of the two doses of the vaccine (Figure 1C)
Our results show that the 2 doses of BBIBP-CorV vaccine were immunogenic in healthy adults aged 18-59 years, with seroconversion rates over 90%
Summary
As of May 29th, 2021, there have been more than 170 million worldwide confirmed cases of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the pandemic has caused more than 5.1 million deaths (https://www.worldometers. info/coronavirus). Immunogenicity and safety assessments postvaccination and monitoring the dynamic human humoral response to SARS-CoV-2 vaccination are important for informing public policy and developing vaccination strategies. The immunological response to SARS-CoV-2 vaccination is often evaluated by monitoring the presence of total binding antibodies and neutralizing antibodies (NAbs) NAb levels have typically been used as the gold standard for evaluating the efficacy of vaccines, such as those against poliomyelitis, smallpox and influenza viruses (Van Remmerden et al, 2012), and NAbs against SARS-CoV-2 have been considered a good indicator of protective immunity in multiple studies (Zinkernagel, 2003). The immunogenicity of SARS-CoV2 inactivated vaccines has been evaluated in several studies (Walsh et al, 2020; Zhang et al, 2020; Al Kaabi et al, 2021; Pan et al, 2021a). The limitations of these studies are the lack of analysis of the individual-specific dynamic changes in NAbs postvaccination and possible related factors
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