Risk Factors Influencing Seroconversion after Inactive SARS-CoV-2 Vaccination in People Living with Obesity

INTRODUCTION: The aim of this study was to investigate the antibody titers against SARS-CoV-2 spike antigens and the risk factors affecting antibody levels in people living with obesity (PwO) after inactive SARS-CoV-2 vaccine (CoronaVac) administration. METHODS: 169 consecutive patients with obesity who visited the Center for Obesity Management at Istanbul University-Cerrahpaşa, Cerrahpaşa Medical Faculty Hospitals, between May and August 2021, were invited to the study. The nonobese control group was recruited from 191 subjects who visited the Cerrahpaşa Hospitals Vaccination Unit. The study group and the nonobese control group have already received two doses of inactive SARS-CoV-2 vaccine. The SARS-CoV-2 IgG nucleocapsid antibody test was administered to patients and control subjects to discover those who had prior SARS-CoV-2 infection. Forty-one patients who had prior infection and received two doses of vaccine were also included in the study as a subgroup. Blood samples were taken on the 3rd to 4th week after the second vaccination. SARS-CoV-2 IgG antibody titers were determined by quantitative serological methods. RESULTS: Antibody titers against SARS-CoV-2 spike antigen of individuals with BMI ≥30.0 kg/m² were significantly lower than those with BMI <30 kg/m² (p = 0.001) in the study group. Moreover, the antibody titers in people with BMI ≥30.0 kg/m² were significantly lower than in those having a BMI <30.0 kg/m² in the subgroup (p = 0.03). Age (p = 0.03), BMI (p = 0.006), and hypertension (p = 0.03) were found to be independent risk factors for antibody response in PwO. Women with non-prior SARS-CoV-2 infection showed a significantly higher antibody response then men (p = 0.001). CONCLUSION: SARS-CoV-2-Immunoglobulin G antibody levels against inactive (CoronaVac) vaccine were found to be lower in PwO compared to nonobese individuals. Antibody titers may be measured, and booster doses should be delivered accordingly in PwO for optimal protection.