New research finds that COVID-19 vaccines protect people of all body weights from hospitalisation and death. This is the outcome of a data review relating to 9 million adults in England, undertaken by researchers based at the University of Oxford.
The finding relates to people who have received two doses of the COVID-19 vaccine and covers those who are categorised as underweight, overweight, or who have obesity. This forms part over continuing assessments in relation to the pandemic.
The research is important since obesity was flagged as a risk factor for severe COVID-19 early in the global pandemic. Furthermore, many vaccine programmes gave priority to people with a body mass index (BMI) over 40 (which is a standard cut-off measure for obesity). This was based on medical assumptions.
The World Health Organisation classifications of BMI are:
- 18.5-24.9kg/m2 for healthy weight;
- Below 18.5 for underweight;
- 25-29.9 for overweight;
- 30 and over as obese.
However, the risk factors relating weight are still present. Here the research found that vaccinated people with underweight or overweight are at greater risk of hospitalisation and death compared with vaccinated people of healthy weight. With the research, characteristics such as age, sex, smoking status, and social deprivation were also accounted for in the analyses.
There is also a concern that underweight people were less likely to be vaccinated, although the reasons for this are not well understood.
The analysis looked at anonymised health records from more than 12 million patients across 1,738 GP practices in England. Of these, 9,171,524 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.
To best gauge vaccine effectiveness, the risk of severe disease in vaccinated versus non-vaccinated people was compared at least 14 days after a second dose. The researchers found that being vaccinated offered high protection across all BMI groups, but that the effect was slightly lower in underweight people.
Lead researcher Dr Carmen Piernas of the University of Oxford’s Nuffield Department of Primary Care Health Sciences sets out the key findings from the study: “Our findings provide further evidence that COVID-19 vaccines save lives for people of all sizes. Our results provide reassurance to people living with obesity that COVID-19 vaccines are equally as effective for them as for people with a lower BMI, and that vaccination substantially lowers their risk of severe illness if they are infected with COVID-19.”
The research appears in the journal Lancet Diabetes and Endocrinology. The paper is titled “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.”
