Covid booster injections ‘less effective for obese people’

OBESE people lose their immunity to Covid more quickly than those of a normal weight and may need more frequent booster vaccinations, scientists have found.

About 55 per cent of people with severe obesity no longer had antibodies that could fight off the virus six months after their second vaccine, according to research by Cambridge University.

In contrast, just 12 per cent of people at a healthy weight lost their protective antibodies by the same point.

Experts studied people with severe obesity attending Addenbrooke’s Hospital in Cambridge, and compared the number and function of immune cells in their blood to those of people of a normal weight.

They said they were unsure why the protection offered by the Covid jab declines more rapidly in people with severe obesity but are investigating if it is hormone-related.

There had been fears that vaccine needles might not be long enough to penetrate far enough into the arms of severely obese people.

However, scientists, including Dr James Thaventhiran from Cambridge’s Medical Research Council Toxicology Unit, have ruled out that theory.

He said: “I don’t think too-short needles were a factor – we found that vaccine-triggered antibody levels, shortly after vaccination, were actually higher in people with obesity.”

During the pandemic, obese people were more likely to be admitted to hospital, require ventilators and die from Covid. The research suggests the waning of vaccine protection may have played a role.

In a separate part of the study, scientists at Edinburgh University tracked the health of 3.5 million people in Scotland who had received two inoculations against Covid.

They found that people with severe obesity – a body mass index greater than 40kg/m2 – had a 76 per cent higher risk of severe Covid outcomes, compared with those with a normal BMI.

Prof Sadaf Farooqi, of the Wellcomemrc Institute of Metabolic Science, said: “More frequent booster doses are likely to be needed in people with obesity. Because of the high prevalence of obesity across the globe, this poses a major challenge for health services.”

The research was published in the journal Nature Medicine.