Antibody responses differ by BMI, age, and sex
In the Italian study, the participants – 158 women and 90 men – were assigned to receive a priming BNT162b2 vaccine dose with a booster at day 21. Blood and nasopharyngeal swabs were collected at baseline and 7 days after the second vaccine dose.
After the second dose, 99.5% of participants developed a humoral immune response; one person did not respond. None tested positive for SARS-CoV-2.
Titers of SARS-CoV-2–binding antibodies were greater in younger than in older participants. There were statistically significant differences between those aged 37 years and younger (453.5 AU/mL) and those aged 47-56 years (239.8 AU/mL; P = .005), those aged 37 years and younger versus those older than 56 years (453.5 vs 182.4 AU/mL; P < .0001), and those aged 37-47 years versus those older than 56 years (330.9 vs. 182.4 AU/mL; P = .01).
Antibody response was significantly greater for women than for men (338.5 vs. 212.6 AU/mL; P = .001).
Humoral responses were greater in persons of normal-weight BMI (18.5-24.9 kg/m2; 325.8 AU/mL) and those of underweight BMI (<18.5 kg/m2; 455.4 AU/mL), compared with persons with preobesity, defined as BMI of 25-29.9 (222.4 AU/mL), and those with obesity (BMI ≥30; 167.0 AU/mL; P < .0001). This association remained after adjustment for age (P = .003).
“Our data stresses the importance of close vaccination monitoring of obese people, considering the growing list of countries with obesity problems,” the researchers noted.
Hypertension was also associated with lower antibody titers (P = .006), but that lost statistical significance after matching for age (P = .22).
“We strongly believe that our results are extremely encouraging and useful for the scientific community,” Dr. Pellini and colleagues concluded.
The authors disclosed no relevant financial relationships. Dr. Iwasaki is a cofounder of RIGImmune and is a member of its scientific advisory board.
This article was updated on 3/8/21.
A version of this article first appeared on Medscape.com.