COVID-19 vaccine protects people of all body weights from hospitalization and death

COVID-19 vaccines greatly reduced the number of cases of severe COVID-19 disease for everyone regardless of their body size, according to a new study published in The Lancet Diabetes & Endocrinology. Vaccine effectiveness was similar for those with a higher BMI and of a healthy weight, but slightly lower in the underweight group, who were also the least likely to have been vaccinated.

In a further analysis of vaccinated people only, among the fewer COVID-19 cases recorded, people of very low and very high BMI were more likely to experience severe disease than vaccinated healthy weight people. This replicates the findings seen in a previous analysis before the vaccination programme commenced.  

Researchers searched anonymised health records from more than 12 million patients across 1,738 GP practices in England taking part in QResearch-a secure database of healthcare information available to verified researchers. Of these, 9,171,524 patients who were over 18 years old, had BMI data, had not previously been infected with SARS-CoV-2 were included in the study.

People were grouped based on their BMI according to four World Health Organisation definitions of 18.5-24.9kg/m2 for healthy weight; below 18.5 for underweight; 25-29.9 for overweight; and 30 and over as obesity with levels adjusted for Asian people to reflect the higher health risks at lower BMI levels in this group. Characteristics such as age, sex, smoking status, and social deprivation were also accounted for in the analyses.