Antibody response with SARS-CoV-2 inactivated vaccine (CoronaVac) in Turkish geriatric population

Background: Sars-CoV-2 infection influences older individuals at the forefront, and there is still limited data on the COVID-19 vaccine response in the geriatric population. This study aimed to assess antibody response after vaccination with SARS-CoV-2 inactivated vaccine and examine possible factors affecting this response in a geriatric population.

Methods: individuals who have been on at least the 28th day after the second dose of the COVID-19 vaccine were included. Comprehensive geriatric assessment tools and the Clinical Frailty Scale were performed. SARS-CoV-2 spike-specific IgG antibodies were detected and, levels ≥1 U/ml were defined as seropositive, <1 U/ml were defined as seronegative.

Results: a total of 497 patients were included and divided into three groups according to the days past after the second dose of the vaccine (Group 1: 28-59 days, Group 2: 60-89 days and Group 3: 90 days and more). Groups included 188, 148 and 171 patients, respectively. Seropositivity rate in each group was 80.9,73.2 and 57.3%, respectively. In Groups 1 and 2, Charlson Comorbidity Index score was higher in the seronegative group (P = 0.023 and P = 0.011, respectively). In Group 3, the prevalence of frailty was significantly higher in the seronegative group (P = 0.002).

Conclusion: to the best of our knowledge, this is the first study assessing the antibody response after vaccination with Sars-CoV 2 inactivated vaccine in the Turkish geriatric population. Moreover, this is the first study revealing the relationship between antibody response and frailty. Larger studies are needed to confirm the antibody response duration and the association between frailty and COVID-19 vaccine response.