COVID Vaccination Protection Wanes Faster in People with Obesity
According to new research from the Universities of Cambridge and Edinburgh, COVID vaccination protection in people with severe obesity wanes faster than in people of normal weight. The study suggests that people with obesity are likely to need more frequent booster doses to maintain their immunity.
Previous studies on COVID vaccines have suggested that antibody levels may be lower in vaccinated people who have obesity and that they may remain at higher risk of severe disease than vaccinated people with normal weight. The reasons for this have, however, remained unclear.
This study, published in the journal Nature Medicine, shows that the ability of antibodies to neutralise the virus (their ‘neutralisation capacity’) declines faster in vaccinated people who have obesity. The findings have important implications for vaccine prioritisation policies around the world.
During the pandemic, people with obesity were more likely to be hospitalised, require ventilators and to die from COVID. In this study, supported by the NIHR Bioresource and funded by UKRI, the researchers set out to investigate how far two of the most extensively used vaccines protect people with obesity compared to those with a normal weight, over time.
A team from the University of Edinburgh looked at real-time data tracking the health of 3.5 million people in the Scottish population as part of the EAVE II study. They looked at hospitalisation and mortality from COVID in adults who received two doses of COVID vaccine (either Pfizer-BioNTech or AstraZeneca).
They found that people with severe obesity (a BMI > 40kg/m2) had a 76% higher risk of severe COVID outcomes, compared to those with a normal BMI. A modest increase in risk was also seen in people with obesity (30-39.9kg/m2), which affects a quarter of the UK population, and those who were underweight. ‘Break-through infections’ after the second vaccine dose also led to hospitalisation and death sooner (from 10 weeks) among people with severe obesity, and among people with obesity (after 15 weeks), than among individuals with normal weight (after 20 weeks).
University of Edinburg leader Prof Sir Aziz Sheikh said: “Our findings demonstrate that protection gained through COVID vaccination drops off faster for people with severe obesity than those with a normal body mass index. 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 vaccine schedules in a post-pandemic UK.”
The University of Cambridge team studied people with severe obesity attending the Obesity clinic at Addenbrooke’s Hospital in Cambridge, and compared the number and function of immune cells in their blood to those of people of normal weight.
They studied people six months after their second vaccine dose and then looked at the response to a third ‘booster’ vaccine dose over time. The Cambridge researchers found that six months after a second vaccine dose, people with severe obesity had similar levels of antibodies to the COVID virus as those with a normal weight – but those antibodies were less effecctive.
The antibodies’ neutralisation capacity was reduced in 55% of individuals with severe obesity were found to have unquantifiable or undetectable ‘neutralising capacity’ compared to 12% of people with normal BMI.
“This study further emphasises that obesity alters the vaccine response and also impacts on the risk of infection,” said first author Dr Agatha van der Klaauw. “We urgently need to understand how to restore immune function and minimise these health risks.”
The researchers found that antibodies produced by people with severe obesity were less effective at neutralising the SARS-CoV-2 virus, potentially because the antibodies were not able to bind to the virus with the same strength.
When given a third (booster) dose of a COVID vaccine, neutralisation capacity was restored in both the normal weight and severely obese groups. But the researchers found that immunity again declined more rapidly in people with severe obesity, putting them at greater risk of infection with time.