Obesity accelerates the loss of COVID-19 vaccine-induced neutralizing antibody capacity, concludes a University of Cambridge study published yesterday in Nature Medicine.
The researchers used the Early Pandemic Evaluation and Enhanced Surveillance of COVID-19 platform to evaluate the relationship between body mass index (BMI) and infection-related hospitalization and death among 3.6 million adults in Scotland. Participants had received a second primary vaccine dose or a first booster dose of Pfizer/BioNTech or AstraZeneca/Oxford vaccine from December 8, 2020, to March 19, 2022.
People with obesity are known to be at elevated risk of poor COVID-19 outcomes and to have weaker immune responses to vaccines against flu, rabies, and hepatitis, the researchers noted.
Frequent booster doses likely needed
Participants with severe obesity (BMI greater than 40 kilograms per square meter [kg/m2]) were at a 76% higher risk of COVID-related hospitalization or death (adjusted rate ratio, 1.76). Infections after the second vaccine dose also led to hospitalization and death starting at 10 weeks among people with severe obesity and 15 weeks among those with milder obesity, compared with 20 weeks among healthy-weight participants.
A longitudinal analysis comparing 28 severely obese people with 41 controls who had a healthy BMI (18.5 to 24.9 kg/m2) showed that the SARS-CoV-2 neutralizing antibody capacity of 55% of severely obese participants was too low to measure, compared with 12% of those with a healthy BMI 6 months after the second vaccine dose—even though they had similar antibody levels.
More frequent booster doses are likely to be needed to maintain protection against COVID-19 in people with obesity.
Regardless of antibody level, people with severe obesity had lower neutralizing capacity than those with a healthy BMI. A third COVID-19 vaccine dose restored neutralizing capacity but was followed by more rapid waning in severely obese than in healthy-BMI participants.
"More frequent booster doses are likely to be needed to maintain protection against COVID-19 in people with obesity," coauthor Sadaf Farooqi, MBBS, PhD, said in a University of Cambridge news release. "Because of the high prevalence of obesity across the globe, this poses a major challenge for health services."