Severe obesity could mean faster decline in immunity to COVID shots

By Cara Murez HealthDay Reporter

FRIDAY, May 12, 2023 (HealthDay News) — Severely obese people may need more frequent COVID-19 boosters to maintain immunity, new research suggests.

“Due to the high prevalence of obesity worldwide, this poses a major challenge for health services,” study co-author Sadaf Farouqi said in a Cambridge press release. She is from the Wellcome-MRC Institute of Metabolic Science in Cambridge.

Previous research has shown that vaccination against COVID has been highly effective in reducing symptoms, hospitalizations and deaths, including for obese people. Still, antibody levels may be lower in vaccinated obese people, potentially putting them at higher risk of serious illness and death, the researchers noted.

To study this, a team from the University of Edinburgh, led by Sheikh Azizassessed the health monitoring data of 3.5 million Scots in the EAVE II study.

Specifically, they looked at COVID-19 hospitalizations and deaths in adults who received two doses of the Pfizer-BioNTech mRNA vaccine or the AstraZeneca vaccine. (The AstraZeneca vaccine is not available in the United States.)

Those with a body mass index (BMI) over 40 – considered extreme obesity – had a 76% higher risk of severe COVID-19 outcomes, compared to those with a normal BMI. A modest increase in risk was also seen in people with a BMI of 30 to 39.9, considered obese rather than severely obese, and in those who were underweight.

People with severe obesity had infections after the second vaccine dose earlier (from 10 weeks) than those with obesity (from 15 weeks) and those with normal weight (20 weeks), according to the study.

“Our results demonstrate that the protection achieved by vaccination against COVID-19 declines faster for people with severe obesity than for those with normal body mass index,” Sheikh said.

Meanwhile, a team from the University of Cambridge studied hospital patients in Cambridge, comparing the number and function of immune cells in their blood to those of people of normal weight.

Six months after a second dose of the vaccine, people with severe obesity had levels of anti-COVID-19 antibodies similar to those with normal weight.

However, the ability of these antibodies to work effectively to fight the virus was reduced in obese people. About 55% of people with severe obesity had unquantifiable or undetectable “neutralization capacity,” compared with 12% of people with a normal BMI, the researchers found.

After a third dose of vaccine, the ability of antibodies to neutralize the virus was restored in both normal-weight and severely obese people. Immunity again waned more rapidly in severely obese people.

“It is promising to see that booster vaccines restore the effectiveness of antibodies for people with severe obesity, but it is worrying that their levels decline more quickly,” said the co-author. Dr. James Thaventhiran, a group leader in the MRC’s Toxicology Unit in Cambridge. “This shows that vaccines work just as well in obese people, but the protection doesn’t last as long.”

The US Centers for Disease Control and Prevention has more on obesity and COVID-19.

SOURCE: University of Cambridge, press release, 11 May 2023

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