In a recent study published in The Lancet, researchers in the UK determined whether an individual with a higher body mass index (BMI) mounted a weaker immune response to a 2019 coronavirus disease vaccine (COVID-19) . In addition, they investigated vaccine uptake and the risk of serious COVID-19 outcomes in these individuals.
Study: BMI associations with COVID-19 vaccine uptake, vaccine efficacy, and risk of serious COVID-19 outcomes after vaccination in England: a cohort study based on the population. Image credit: GrooTrai / Shutterstock
Fund
By 2021, around 82.5% of the UK population had received a two-dose regimen of COVID-19 vaccines. However, there is no information on the adoption of COVID-19 vaccination for the nine million UK population stratified by BMI groups.
Studies have shown that the effectiveness of the flu vaccine is lower among people with a higher BMI. Because COVID-19 is also a respiratory infection; therefore, it justifies investigating whether there is an association between BMI and the effectiveness of the COVID-19 (VE) vaccine. In addition, long-term evidence on a range of COVID-19 outcomes in all BMI groups is also needed because it could reveal the need for alternative risk mitigation strategies and targeted vaccine enhancement programs for people at high risk.
About the study
In the present cohort observational study, researchers used the QResearch database of general practice records to identify individuals for whom BMI data were available and who were vaccinated between December 8, 2020 and on November 17, 2021 in England. They calculated vaccine uptake as the fraction of individuals with zero, one, two, or three doses of vaccine in four BMI categories. The BMI categories were: low weight (<18,5 kg/m2), pes saludable (18,5 a 24,9 kg/m2), sobrepès (25 a 29 kg/m2) i obesitat (>30 kg / m2). The analysis of the study took into account several demographic confounding factors, including age, sex, ethnicity, socioeconomic status, and relevant comorbidities.
The team also investigated VE against coronavirus 2 (SARS-CoV-2) infection of severe acute respiratory syndrome. In addition, using a matching case design and controls, they estimated the probability ratio (OR) of severe COVID-19 outcomes in vaccinated individuals compared to those who had not, taking into account the dose of the vaccine and the time elapsed since vaccination. Finally, they estimated the risk of severe COVID-19 outcomes associated with BMI after vaccination using multivariable cox proportional risk models.
Study results
Of the 9,171,524 participants, 5,666,461 were positive for COVID-19 during the duration of the study. Finally, 32,808 positive participants for COVID-19 were hospitalized and 14,389 died. Of all study participants, 19.2% were not vaccinated. Of the remaining participants, 3.1%, 52.6%, and 25% received one, two, and three doses of vaccine, respectively. The mean age of the study participants was 52 years and the mean BMI was 26.7 kg / m².
Proportion of people who did not receive any, one, two or three doses of vaccination by age and BMI group
Vaccine uptake was lower among people who were underweight compared to people who were overweight or obese (70 to 83% versus 80%). These people were 40 years of age or older and had received two or three doses of vaccine. In all four BMI groups, the results of the study were significantly heterogeneous in terms of protection against severe COVID-19.
Consequently, hospitalization ORs for low weight, normal weight, overweight, and obesity were 0.51, 0.34, 0.32, and 0.32, respectively. Similarly, the ORs of COVID-19-related deaths for low weight, normal weight, overweight, and obesity were 0.60, 0.39, 0.30, and 0.26, respectively. Compared with unvaccinated individuals, hospitalization and death were higher after 14 days of the second vaccine dose in vaccinated individuals. In addition, in vaccinated participants, the correlation between BMI and hospitalization and death by COVID-19 was linear after the first and J-shaped after the second dose of vaccine. The researchers observed a reverse U-shaped association between BMI and the third dose of vaccine, indicating that reinforcement was needed to confer complete protection to obese people.
In addition, the first and second sets of sensitivity analyzes used two different cohorts. The first set had people for whom BMI records for two years prior to cohort enrollment were available. Their VE showed smaller ORs compared to the primary study analysis; however, the results of both sensitivity analyzes generally agreed with the main findings of the study.
Risk of serious COVID-19 outcomes after vaccination Risk estimates after 14 days of each vaccine dose. Adjusted for age, calendar week, sex, ethnicity, socioeconomic status, region, smoking status, hypertension, type 1 diabetes, type 2 diabetes, cardiovascular disease, and residence status. Hospital admissions for COVID-19 after the first dose (A), second dose (B) and third dose (C) and deaths from COVID-19 after the first dose (D), second dose (E) and third dose ( F)).
Conclusions
The large cohort study based on the current population showed that COVID-19 vaccines confer protection against serious diseases; however, of similar magnitude in obese people and normal weight. However, VE had been reduced for low-weight people among those with lower vaccine absorption at all ages. In addition, the results of the study indicated a higher risk of developing severe COVID-19 in obese and low-weight people in the vaccinated cohort because they had lower vaccine absorption and showed very low VE. Overall, these results highlighted the need for concerted efforts to increase vaccine uptake in people with a BMI below 18.5 kg / m2. In fact, raising awareness among people to maintain a healthy weight could help reduce the burden of COVID-19.
Magazine reference:
- BMI associations with COVID-19 vaccine uptake, vaccine efficacy, and risk of serious COVID-19 outcomes after vaccination in England: a population-based cohort study, Carmen Piernas, Martina Patone, Nerys M Astbury, Min Gao, Aziz Sheikh, Kamlesh Khunti, Manu Shankar-Hari, Sharon Dixon, Carol Coupland, Paul Aveyard, Julia Hippisley-Cox, Susan A Jebb, The Lancet 2022, DOI: