Analysis of Serum Antibody Level after COVID-19 Vaccine and Side Effects after Vaccine

Abstract

Background: COVID-19 has caused a large number of deaths, in the elderly. In this situation, vaccines have been considered the main strategy to combat COVID-19 and were developed worldwide in 2020. One problem with COVID-19 vaccination is side effects after vaccination. In this report, we identify the relationship between side effects and elevation of antibodies as determined by monitoring several kinds of antibodies against COVID-19. Objective: We investigated whether the antibody level changed depending on side effects after COVID-19 vaccination. Methods: Healthy volunteers, who received two vaccinations between 10 March and 7 May 2021, were collected for this study. Information including age, gender, smoking history, medical history including allergies and side reactions after vaccination was obtained by questionnaire. Serum levels of antibodies of IgG and IgM against each S1, SP, and NP antigens of COVID-19 were evaluated frequently for 3 - 4 months after the first vaccination. Result: Ten employees working at Iwate Medical University were evaluated in this study. Side effects were observed in 7 of 10 patients, and grade 2 side effects in all 3 patients with a history of allergic disease. Serum S1 and SP IgG were elevated sufficiently in all patients. In all patients, IgG antibody titers fell below the cutoff point in approximately 3 months. No cases had elevated NP antibodies. SP IgM was elevated in three cases; all three cases with elevated IgM had allergic disease and the degree of side effects was relatively higher. Subjects with long-lasting elevated SPIgM were observed. Conclusion: S1 IgG and SP IgG exceeded the cutoff in all subjects after vaccination but decreased below the cutoff in all subjects within 4 months, regardless of side effects or allergic history. On the other hand, elevated SPIgM was suspected to be related to side effects and history of allergies, and cases with persistent elevation of SPIgM were observed.