COVID-19 vaccines reduce odds for severe disease, regardless of BMI
COVID-19 vaccines are effective in reducing the risk for hospitalization and death in all BMI groups, though the odds for adverse outcomes were higher for vaccinated people with very high or very low BMI compared with normal weight.
“We had concerns that perhaps COVID-19 vaccines were less effective in people with obesity, given previous evidence from flu vaccines,” Carmen Piernas, PhD, honorary university research lecturer at the University of Oxford in the U.K., and Ramón y Cajal fellow at the University of Granada in Spain, told Healio. “When we compared vaccinated people against unvaccinated ones, we observed that vaccines were highly effective against COVID-19 hospital admission or death, regardless of body weight. However, when we looked at the vaccinated population only, although we observed a large reduction of severe cases, we still saw increased risk of COVID-19 severity in people at low and high body weights compared to vaccinated people of a healthy weight.”
Piernas and colleagues conducted a population-based cohort study of 9,171,524 adults aged 18 years and older in England registered with a general practice in the QResearch database between Dec. 8, 2020, and Nov. 17, 2021, with BMI data available. Data were linked to the National Health Service (NHS) Digital database of positive tests for SARS-CoV-2 infection, the U.K. National Immunisation Management Service database, Hospital Episode Statistics and death certificates from the U.K. Office for National Statistics. The last measured BMI was used for each individual. Participants were grouped in underweight, healthy weight, overweight and obesity categories based on WHO and U.K. National Institute for Health and Care Excellence classification. Hospital admission and death were the main outcomes used to assess vaccine efficacy in the BMI subgroups.
The findings were published in The Lancet Diabetes & Endocrinology.
COIVD-19 vaccines lower odds of severe disease
At the end of the study period, 19.2% of the study cohort was unvaccinated, 3.1% received one vaccine dose, 52.6% received two doses and 25% received three doses. More than 80% of adults with overweight or obesity aged 40 years and older had received two or three doses by the end of the study.
Vaccinated adults with underweight (OR = 0.51; 95% CI, 0.41-0.63), normal weight (OR = 0.34; 95% CI, 0.32-0.36), overweight (OR = 0.32; 95% CI, 0.3-0.34) and obesity (OR = 0.32; 95% CI, 0.3-0.34) had a reduced likelihood for COVID-19 hospital admission 14 days after a second vaccine dose compared with unvaccinated adults. The odds were further reduced for those who received a third vaccine dose.
The odds for COVID-19 death were also lower 14 days after a second vaccine dose for adults with underweight (OR = 0.6; 95% CI, 0.36-0.98) normal weight (OR = 0.39; 95% CI, 0.33-0.47), overweight (OR = 0.3; 95% CI, 0.25-0.35) and obesity (OR = 0.26; 95% CI, 0.22-0.3) compared with unvaccinated adults.
Highest risks observed with very low, very high BMI among vaccinated adults
After the second dose, there were J-shaped associations between BMI and the risk for COVID-19 hospitalization and death, with the highest risks observed in adults with a BMI less than 18 kg/m2 or higher than 40 kg/m2.
“Last year we reported a strong association between BMI and COVID-19 severity with people at very low and very high levels of BMI showing increased risks,” Piernas said. “We had hoped that this association would have disappeared after vaccination, but it didn’t. Thankfully, given the high effectiveness of the vaccines, the absolute number of severe cases has been reduced massively. But among the fewer severe cases that are happening, those with low or high body weights are at increased risks compared with people of a healthy weight.”
In a related commentary, Annelies Wilder-Smith, MD, PhD, adjunct professor, and Annika Frahsa, PhD, head of research group at the Institute of Social and Preventive Medicine at the University of Bern in Switzerland, wrote that the findings not only underscore the importance of vaccination, but also the importance of reducing the prevalence of obesity.
“This large cohort study emphasizes the crucial role of obesity in the COVID-19 pandemic,” Wilder-Smith and Frahsa wrote. “Obesity and COVID-19 appear to be a detrimental intersection, one that has also been observed for influenza and other infectious diseases. Furthermore, people with obesity in the U.K. have also been affected by the pandemic lockdown measures with increased overeating, reduced physical activity behavior, and increased barriers to weight management. Tackling obesity as a societal problem now will help mitigate the disastrous consequences of the current COVID-19 pandemic and those of future pandemics.”
Reference:
- Wilder-Smith A, et al. Lancet Diabetes Endocrinol. 2022;doi:10.1016/S2213-8587(22)00170-X.
For more information:
Carmen Piernas, PhD, can be reached at carmen.piernas-sanchez@phc.ox.ac.uk.
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