Researchers from the Universities of Cambridge and Edinburgh analysed the EAVE II dataset to identify 1.7 million people in Scotland who had 2-3 vaccines and a body mass index (BMI) record. Of these, half a million had obesity and more than 98,000 people were severely obese.

The study, published in Nature Medicine, found that the ability of antibodies to neutralise the SARS-CoV-2 virus declines faster in vaccinated people with obesity or severe obesity.

This image was created by the Usher Institute, The University of Edinburgh to accompany a collaborative study between The University of Cambridge and the EAVE II team. EAVE II is supported by the Medical Research Council (UKRIMC_PC19075) and the National Institute for Health and Care Research (NIHR135575). © 2022 Usher Institute, The University of Edinburgh. All rights reserved.

Between 14 September 2020 and 19 March 2022, 10,983 people were admitted to hospital or died due to COVID-19 after 2-3 vaccine doses. People with severe obesity were 76% more likely than those within the healthy BMI range to be admitted to hospital or die of COVID-19. A modest increase in risk was also seen in people with obesity, which affects a quarter of the UK population.

The researchers also found that people with severe obesity and obesity were at risk of becoming seriously unwell from 10 and 15 weeks after the vaccination respectively, compared with 20+ weeks for people in the healthy BMI range.

Professor Sir Aziz Sheikh, Director of the Usher Institute, said: “Our findings demonstrate that protection gained through COVID-19 vaccination drops off faster for people with severe obesity than those with a BMI in the healthy range.

“Using large-scale data assets such as the EAVE II Platform in Scotland have enabled us to generate important and timely insights that enable improvements to the delivery of COVID-19 vaccine schedules in a post-pandemic UK.”

During the pandemic, people with obesity were at higher risk of hospitalisation and death from COVID-19. This research suggests that more frequent boosters may need to be offered to people with obesity for continued protection against severe illness.

Read a summary of the research