Sex‐associated differences between BMI and SARS‐CoV‐2 antibody titers following the BNT162b2 vaccine

OBJECTIVE: This study investigated the sex‐associated difference in the impact of obesity on antibody response to a COVID‐19 vaccine. METHODS: This study included 2,435 health care workers who received two doses of the BioNTech, Pfizer (BNT162b2) vaccine and participated in a serological survey, during which they were tested for anti‐SARS‐CoV‐2 spike immunoglobin G (IgG) antibodies and asked for information on height, weight, and vaccination history via a questionnaire. Multivariable linear regression analysis was used to estimate the geometric mean titers (GMT) of antibodies for each sex and BMI category. RESULTS: The relationship between BMI and anti‐SARS‐CoV‐2 spike IgG titers markedly differed by sex (p value for interaction = 0.04). Spike IgG antibody titers tended to decrease with increasing BMI in men (p value for trend = 0.03); GMT (95% CI) were 6,093 (4,874‐7,618) and 4,655 (3,795‐5,708) for BMI < 18.5 and ≥30 kg/m(2), respectively. In contrast, spike IgG antibody titers did not significantly differ across BMI categories in women (p value for for trend = 0.62); GMT (95% CI) were 6,171 (5,714‐6,665) and 5,506 (4,404‐6,883) for BMI <18.5 and ≥30, respectively. CONCLUSIONS: Higher BMI was associated with lower titers of SARS‐CoV‐2 spike antibodies in men, but not in women, suggesting the need for careful monitoring of vaccine efficacy in men with obesity, who are at high risk of severe COVID‐19 outcomes.