Investigation of IgG antibody levels among healthcare workers vaccinated with inactivated COVID-۱۹ vaccine using indirect ELISA

This study was conducted to investigate variations in SarsCoV-۲-specific IgG levels over a ۵-month period in healthcare workers who received two doses of CoronaVac vaccine.  Blood samples were collected from ۱۲۲ participants on days ۱۴, ۵۶ and ۱۵۰ following the second dose of the vaccination. SarsCoV-۲ specific IgG antibody titres of the participants were measured using the QuantiCOR ELISA kit. Demographic data of the participants were recorded. Seropositivity on ۱۴th, ۵۶th and ۱۵۰th days in the previously uninfected group was ۴۴.۸%, ۵۰.۷% and ۳۲.۸%, respectively. In the previously infected group, seropositivity was detected in ۸۷.۲%, ۹۲.۷% and ۴۳.۶% of the participants, respectively. While a statistically significant difference was determined between the two groups in terms of seropositivity on the ۱۴th and ۵۶th days, no statistical difference was found on the ۱۵۰th day. The data of this study indicated that the CoronaVac vaccine provided sufficient immunity in previously infected individuals, though the duration of immunity was short. It is suggested that CoronaVac vaccine would be more appropriate to use as a booster in order to increase the effectiveness of a vaccine rather than the first vaccination, or to vaccinate people who have been infected before.

Keywords:

COVID-۱۹ , Healthcare workers , CoronaVac , IgG , Elisa