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COVID vaccines protect people of all body weights

In a recently published study in The lancetresearchers in the UK have determined whether a person with a higher body mass index (BMI) develops a weaker immune response to a coronavirus disease 2019 (COVID-19) vaccine. In addition, they examined vaccine uptake and the risk of severe COVID-19 outcomes in such individuals.

Study: Associations of BMI with COVID-19 vaccine uptake, vaccine efficacy and risk of severe post-vaccination COVID-19 outcomes in England: a population-based cohort study. Photo Credit: GrooTrai/Shutterstock

background

By 2021, around 82.5% of the United Kingdom (UK) population had received two-dose therapy with COVID-19 vaccines. However, there is no information on the uptake of the COVID-19 vaccination for the nine million British population, stratified by BMI groups.

Studies have shown that the effectiveness of the influenza vaccine is lower in people with a higher BMI. Since COVID-19 is also a respiratory infection; Therefore, it should be investigated whether there is an association between BMI and COVID-19 vaccine (VE) effectiveness. In addition, long-term evidence for a range of COVID-19 outcomes across all BMI groups is also needed, as it may indicate the need for alternative risk reduction strategies and targeted immunization refresher programs for high-risk individuals.

About the study

In the present observational cohort study, researchers used the QResearch database of general practice records to identify individuals for whom BMI data were available and who were vaccinated between 8 December 2020 and 17 November 2021 in England. They calculated vaccine uptake as the proportion of people with zero, one, two, or three vaccine doses in four BMI categories. The BMI categories were – underweight (<18.5kg/m2), healthy weight (18.5 to 24.9 kg/m2), overweight (25 to 29 kg/m2) and obese (>30kg/m2). The study analysis considered several demographic confounders, including age, gender, race, socioeconomic status, and relevant comorbidities.

The team also studied VE against infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Also, using a matched case-control design, they estimated the odds ratio (OR) for severe COVID-19 outcomes in vaccinated versus non-vaccinated subjects, taking into account vaccine dosing and time elapsed since vaccination . Finally, they estimated the risk of severe COVID-19 outcomes related to post-vaccination BMI using multivariable Cox proportional hazards models.

study results

Of 9,171,524 participants, 5,666,461 were positive for COVID-19 during the study period. Eventually, 32,808 COVID-19 positive participants were hospitalized and 14,389 died. Of all study participants, 19.2% were unvaccinated. Of the remaining participants, 3.1%, 52.6%, and 25% received one, two, and three doses of vaccine, respectively. The average age of the study participants was 52 years, the average BMI was 26.7 kg/m².

​​​​​​​Proportion of people who received none, one, two or three doses of vaccine by age and BMI groupProportion of people who received none, one, two or three doses of vaccine by age and BMI group

Vaccine uptake was lower in underweight subjects than in overweight or obese subjects (70 to 83% vs. over 80%). These people were 40 years or older and had received two or three doses of the vaccine. Across all four BMI groups, study results regarding protection against severe COVID-19 were significantly heterogeneous.

Accordingly, the hospitalization ORs for underweight, normal weight, overweight, and obese were 0.51, 0.34, 0.32, and 0.32, respectively. Likewise, the ORs of COVID-19-related deaths for underweight, normal weight, overweight, and obesity were 0.60, 0.39, 0.30, and 0.26, respectively. Hospitalizations and deaths after 14 days of the second dose of vaccine were higher in vaccinated individuals compared to unvaccinated individuals. Also, in the vaccinated participants, the correlation between BMI and COVID-19 hospitalization and death was linear after the first and J-shaped after the second vaccine dose. The researchers observed an inverse U-shaped association between BMI and the third vaccine dose, indicating that a booster dose was needed to confer full protection on obese people.

In addition, two different cohorts were used for the first and second set of sensitivity analyses. The first set contained individuals for whom BMI records were available for two years prior to cohort enrollment. Their VE showed smaller ORs compared to the primary study analysis; However, the results of both sensitivity analyzes were generally consistent with the main findings of the study.

Risk of serious consequences of COVID-19 after vaccination Risk estimates after 14 days after each vaccination dose.  Adjusted for age, week of the year, gender, race, socioeconomic status, region, smoking status, hypertension, type 1 diabetes, type 2 diabetes, cardiovascular disease, and nursing home status.  COVID-19 hospital admissions after the first dose (A), second dose (B), and third dose (C), and COVID-19 deaths after the first dose (D), second dose (E), and third dose (F).Risk of serious consequences of COVID-19 after vaccination Risk estimates after 14 days after each vaccination dose. Adjusted for age, week of the year, gender, race, socioeconomic status, region, smoking status, hypertension, type 1 diabetes, type 2 diabetes, cardiovascular disease, and nursing home status. COVID-19 hospital admissions after the first dose (A), second dose (B), and third dose (C), and COVID-19 deaths after the first dose (D), second dose (E), and third dose (F).

Conclusions

The recent large population-based cohort study has shown that COVID-19 vaccines offer protection against serious diseases; however, in a similar magnitude in overweight and normal-weight people. However, VE had decreased for underweight individuals among those with lower vaccine uptake across all age groups. In addition, study results indicated a higher risk of developing severe COVID-19 in obese and underweight individuals in the vaccinated cohort, as they had lower vaccine uptake and greatly reduced VE. Taken together, these results highlighted the need for a concerted effort to increase vaccine uptake in people with a BMI less than 18.5 kg/m2. Indeed, raising people’s awareness of maintaining a healthy weight could help reduce the burden of COVID-19.

Magazine reference:

  • Associations of BMI with COVID-19 vaccine uptake, vaccine efficacy, and risk of severe post-vaccination COVID-19 outcomes 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: https://doi.org/10.1016/S2213-8587(22)00158- 9 , https://www.thelancet.com/journals/landia/article/PIIS2213-8587(22)00158-9/fulltext

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