Covid-19 vaccines drastically helped cut down the infections for everyone regardless of their body size, according to a study published in The Lancet Diabetes and Endocrinology. The researchers reached this conclusion after assessing health records of 90 lakh adults in England.
Vaccine effectiveness was similar for those with a higher body mass index (BMI) and of a healthy weight, but slightly lower in the underweight group, who were also the least likely to have been vaccinated, the researchers said.
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, they said.
"Our findings provide further evidence that Covid-19 vaccines save lives for people of all sizes," said study lead author Carmen Piernas from the University of Oxford, UK.
"Our results provide reassurance to people with obesity that Covid-19 vaccines are equally as effective for them as for people with a lower BMI, and that vaccination substantially reduces their risk of severe illness if they are infected with Covid-19," Piernas said.
The data also highlights the need for targeted efforts to increase vaccine uptake in people with a low BMI, where uptake is currently lower than for people with a higher BMI, the researchers said.
They searched anonymised health records from more than 12 million patients in England taking part in QResearch - a secure database of healthcare information available to verified researchers.
Of these, 9,171,524 (9.1 lakh) patients who were over 18 years old, had BMI data, and had not previously been infected with SARS-CoV-2 were included in the study.
People were grouped based on their BMI according to WHO definitions. Characteristics such as age, sex, smoking status, and social deprivation were also accounted for in the analyses.
Of over 90 lakh people included in the study, 566,461 (over 5.6 lakh) tested positive for SARS-CoV-2 during the study from December 8, 2020 (date of the first vaccine given in the UK) to November 17, 2021.
Of those, 32,808 were admitted to hospital and 14,389 died. At the end of the study period, 23.3 per cent of the healthy weight group, 32.6 per cent of the underweight group, 16.8 per cent of the overweight group and 14.2 per cent of the group with obesity had had no doses of any Covid-19 vaccine.
To understand vaccine effectiveness, the researchers compared risk of severe disease in vaccinated versus unvaccinated people at least 14 days after a second dose.