Clinical and laboratory features in health care volunteers with inactivated SARS-CoV-2 vaccination

To better optimize the inactivated vaccine-induced immune response and improve vaccine protection efficiency, a preliminary study was conducted on the influencing factors of producing neutralizing antibody (NAb) titers against the inactivated coronavirus disease 2019 (COVID-19) vaccine.

A total of 91 health care volunteers were enrolled from the Immunology Division of the Laboratory Department of Chongqing General Hospital from February to March 2021. The study had a cross-sectional design. All of the volunteers were scheduled to receive a complete dose regimen of the inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine and the vaccination interval between 2 doses was 14 days. Clinical and laboratory features were collected for further analysis.

The NAb titers gradually increased after COVID-19 vaccination, and 72.53% (n = 66) of the volunteers had NAbs after the second dose. Eight variables, including CD16⁺CD56⁺ NK cell level before the first dose (HR = 0.94, p = 0.02), CD16⁺CD56⁺ NK cell level after the second dose (HR = 0.94, p = 0.03), interleukin (IL)-2 level before the first dose (HR = 2.09, p = 0.05), mean corpuscular volume (HR = 0.86, p = 0.02), serum urea level (HR = 0.69, p = 0.05), increment of CD19⁺ B cells (HR = 0.86, p = 0.03), increment of CD4⁺/CD8⁺ T cells (HR = 0.21, p = 0.03), and increment of the IL-6 level (HR = 0.75, p = 0.04) demonstrated a correlation with the NAb titers after COVID-19 vaccination. In the multivariate logistical regression analysis, the serum urea level (HR = 2.32, P = 0.03) and increment of CD19⁺ B cells (HR = 1.96, p = 0.03) were positively correlated with the NAb titers. The principal component analysis effectively distinguished the response after COVID-19 vaccination. The Pearson correlation analysis indicated that the CD19⁺ B cell level (r = 0.23, p < 0.001) and IL-2 (r = 0.24, p < 0.001) and IL-6 levels (r = 0.22, p < 0.001) were weakly positively correlated with the concentration of NAbs.

The NAbs titers of the inactivated vaccines were positively correlated with the ratio of CD19⁺ B cell, IL-6, and IL-2 levels in the serum, which provide clinical guidance for inactivated SARS-CoV-2 vaccines.