Spike Protein IgG Antibody Immune Response Following SARS-CoV-2 Vaccination and Individual Factors Related to Its Level

Abstract

Objective: To determine the strength of the immune response following SARS-CoV-2 vaccination and the individual factors related to its level.

Design: Of our staff members who received Pfizer-BioNTech or Moderna vaccines between May and July 2021, 152 consented to participate in this study. Spike protein IgG antibody levels were measured at least 7 days after the second dose of the vaccine. We analyzed how age and sex of the participants, side effects, and vaccine type were related to antibody level.

Results: All the participants had detectable spike protein IgG antibody levels (median level: 7,314AU/mL) after vaccination. Individuals aged<45 years old showed significantly higher antibody levels than those aged ≧ 45 years old (p<0.01). Individuals whose body temperatures exceeded 37.5°C after the vaccination showed significantly higher antibody levels than those with body temperatures ≦ 37.4°C (p<0.01). Individuals who received the Moderna vaccine showed higher antibody levels than those who received Pfizer-BioNTech (p<0.01). Antibody levels declined gradually with time.

Conclusions: These results suggest that spike protein antibody levels are associated with age and degree of fever of the individuals receiving the vaccine and the vaccine type administered. Antibody levels declined with time. We believe that administering booster vaccinations should be reconsidered.