COVID-19 vaccine benefit people of all weights
Friday July 1st 2022
COVID-19 vaccines protect people of all weights from severe disease, according to the results of a UK study published today.
Research led by the University of Oxford, UK, and published in *The Lancet Diabetes & Endocrinology*, shows that vaccines were effective among those with a healthy weight and excessive weight.
It was slightly less effective in individuals who were underweight – this group was also less likely to have had the vaccine.
When the researchers analysed 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.
Obesity was highlighted as a risk factor for severe COVID-19 early in the pandemic, however, little was known until now about the effectiveness of the vaccines for people with obesity.
Lead author Dr Carmen Piernas of the Nuffield Department of Primary Care Health Sciences, University of Oxford, said: “Our findings provide further evidence that COVID-19 vaccines save lives for people of all sizes.
“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.
“These data also highlight 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.”
Researchers analysed anonymised health records from more than 12 million patients across 1,738 GP practices in England taking part in QResearch.
Included in the study were 9,171,524 adult patients who had BMI data and had not previously been infected with SARS-CoV-2.
People were grouped based on their BMI according to four World Health Organisation definitions: 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.
Out of the total study group, 566,461 tested positive for COVID-19 during the study from 8 December 2020 – the date of the first vaccine given in the UK – to 17 November, 2021. Of those, 32,808 were admitted to hospital and 14,389 died.
At the end of the study period, 23.3% of the healthy weight group (817,741 of 3,509,231 people), 32.6% of the underweight group (104,488 of 320,737 people), 16.8% of the overweight group (513,570 of 3,062,925 people) and 14.2% of the group with obesity (322,890 of 2,278,649 people) had had no doses of any COVID-19 vaccine.
When the researchers compared risk of severe disease in vaccinated compared to non-vaccinated people at least 14 days after a second dose, they found being vaccinated offered high protection across all BMI groups, but that the effect was slightly lower in underweight people.
Underweight vaccinated people had about half the likelihood of being hospitalised or dying compared with unvaccinated people of the same BMI, while people in the healthy and high BMI groups who were vaccinated were about 70% less likely to be hospitalised than unvaccinated people.
When they examined data from vaccinated people only, they found a significantly higher risk of severe disease at low and at high BMI compared with a healthy BMI following two vaccines: a BMI of 17 was linked to a 50% increase in risk of hospitalisation compared with a healthy BMI of 23, and a very high BMI of 44 had three times the risk of hospitalisation compared with a healthy BMI.
The cause of the increased risk among people with obesity is unknown, but it is consistent with the higher rate of seasonal ‘flu infections in people with a higher BMI.
Limitations to the study include some measurements of BMI being self-reported or on data recorded in GP records before the study onset that could be outdated. The limited numbers of people who had had three doses by the study close meant the effects of booster jabs could not be investigated, and data did not allow for researchers to investigate between Pfizer, AstraZeneca or Moderna vaccines, nor virus variants.
Piernas C, Patone M, Astbury NM et al. Associations of BMI with COVID-19 vaccine uptake, vaccine effectiveness, and risk of severe COVID-19 outcomes after vaccination in England: a population-based cohort study. *The Lancet Diabetes & Endocrinology* 1 July 2022
Tags: Diabetes | Diet & Food | Fitness | Flu & Viruses | UK News
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