Analysis in antibody levels in blood of patients infected with Coronavirus disease 2019 after inoculation with novel coronavirus inactivated vaccine and disease status

  Objective  To explore whether novel coronavirus inactivated vaccine has protective effects or not on Coronavirus disease 2019(COVID-19) people infected with Delta variant of the virus after vaccination.

  Methods  During the period from July 20, 2021 to August 27, 2021, the data of 47 patients with COVID-19 who were inoculated with inactivated vaccines(one dose or two doses of vaccine against COVID-19) in the isolation ward of our hospital, and the changes in the dynamic levels of blood immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against COVID-19 were observed, and the results were compared with 30 patients with COVID-19 who were not vaccinated inactivated vaccine for COVID-19.

  Results  The severity of illness of unvaccinated adult patients was significantly heavier than that of patients who received two doses of vaccine; within 4 weeks of course of disease, the blood IgM antibody titer of patients with COVID-19 showed a trend of firstly increasing, then decreasing and finally recovering. The patients receiving two doses of vaccine quickly reached the peak in the second week, while most of patients with one dose of vaccine and those without vaccination reached the peak at the third week of vaccination. The peak titer showed a significant difference among the three groups(P < 0.05). The titer of IgG antibody in 77 adult patients with COVID-19 peaked at 2 or 3 weeks and decreased at week 4 but still remained at a high level. The peak titer of the unvaccinated adult group was significantly lower than that of the two doses of vaccine group and the one dose of vaccine group(P < 0.05).

  Conclusion  The inactivated vaccine has an immune protection effect in patients with new coronary pneumonia, which can reduce the severity of the disease. The body-specific immune responses induced by inactivated vaccines may attenuate over time.