Study shows obesity accelerates loss of immunity to Covid-19 vaccination

17.05.2023 15:51

Scientists at the Universities of Cambridge and Edinburgh have found that protection from the Covid-19 vaccination decreases faster in people with severe obesity 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.

Clinical trials have shown that Covid-19 vaccines are highly effective in reducing symptoms, hospitalizations and deaths caused by the virus, including in people with obesity. Previous studies suggest that antibody levels may be lower in vaccinated people with obesity and that they may remain at higher risk of severe disease than vaccinated people of normal weight. However, the reasons for this remained unclear.

This study, published in the journal Nature Medicine, shows that the ability of antibodies to neutralize the virus declines more quickly in vaccinated people with obesity. The findings have important implications for vaccine prioritization guidelines around the world.

During the pandemic, people with obesity were more likely to be hospitalized, require ventilators and die from Covid-19. In this study, supported by the NIHR Bioresource and funded by UKRI, researchers wanted to examine the extent to which two of the most commonly used vaccines protect people with obesity compared to people of normal weight over time.

A University of Edinburgh team led by Prof Sir Aziz Sheikh examined real-time data tracking the health of 3.5 million people in the Scottish population as part of the EAVE II study. They examined hospitalizations and mortality due to Covid-19 in adults who received two doses of the Covid-19 vaccine (either Pfizer-BioNTech BNT162b2 mRNA or AstraZeneca ChAdOx1).

They found that people with severe obesity (BMI over 40 kg/m2) had a 76 % higher risk of severe Covid-19 courses than people with a normal BMI. A small increase in risk was also seen in people with obesity (30-39.9 kg/m2), which affects a quarter of the UK population, and in people who are underweight. “Breakthrough infections” after the second dose of vaccination also led to earlier hospitalizations and death in people with severe obesity (from 10 weeks) and in people with obesity (after 15 weeks) than in people with normal weight (after 20 weeks). ).

Prof Sir Aziz Sheikh said: "Our results show that the protection gained from Covid-19 vaccination wanes more quickly in people with severe obesity than in people with a normal body mass index." Using large data sets such as the EAVE II platform in Scotland, we have been able to gain important and timely insights that will enable improvements in the delivery of Covid-19 vaccination plans in a post-pandemic Britain.”

The team from the University of Cambridge – jointly led by Dr. James Thaventhiran, from the MRC Toxicology Unit and Prof Sadaf Farooqi from the Wellcome-MRC Institute of Metabolic Science studied people with severe obesity who attended the obesity clinic at Addenbrooke's Hospital in Cambridge and compared the number and function of immune cells in their blood with those from people of normal weight.

They studied people six months after their second dose of vaccine and then looked at the response to a third "booster" dose of vaccine over time. The Cambridge researchers found that people with severe obesity had similar levels of antibodies to the Covid-19 virus as people of normal weight six months after a second dose of vaccine.

But the ability of these antibodies to efficiently fight the virus (known as “neutralization capacity”) was reduced in people with obesity. 55 % of those with severe obesity were found to have unquantifiable or undetectable “neutralizing ability,” compared to 12 % of those with normal BMI.

“This study also highlights that obesity alters vaccine response and also impacts infection risk,” said Dr. Agatha van der Klaauw from the Wellcome-MRC Institute of Metabolic Science and first author of the study. “We urgently need to understand how we can restore immune function and minimize these health risks.”

The researchers found that antibodies produced by people with severe obesity were less effective at neutralizing the SARS-CoV-2 virus, possibly because the antibodies were not able to bind to the virus with the same strength.

When a third (booster) dose of a Covid-19 vaccine was given, the ability of antibodies to neutralize the virus was restored in both the normal weight and severely obese groups. However, the researchers found that immunity again declined more quickly in people with severe obesity, putting them at greater risk of infection over time.

Dr. James Thaventhiran, group leader of the MRC Toxicology Unit in Cambridge and co-lead author of the SCORPIO study, said: "It is promising to see that booster vaccinations restore the effectiveness of antibodies in people with severe obesity, but at the same time it is also worrying." Values fall more quickly after just 15 weeks. This shows that the vaccines work just as well in people with obesity, but the protection does not last as long.”

Prof Sadaf Farooqi, from the Wellcome-MRC Institute of Metabolic Science and co-lead author of the SCORPIO study, said: "More frequent booster doses are likely to be needed to maintain protection against Covid-19 in people with obesity." Due to the high prevalence of obesity worldwide “This represents a major challenge for the healthcare system.”

reference

AA van der Klaauw et al., 'Accelerated waning of the humoral response to Covid-19 vaccines in obesity', Nature Medicine (2023). DOI: 10.1038/s41591-023-02343-2