Although Covid vaccinations are extremely successful, other populations may not respond as strongly to them. These populations include the elderly and those whose immune systems have been compromised, maybe as a result of cancer or other illnesses. They often already face increased danger with Covid.
The chance of developing severe COVID is further enhanced by obesity and its link to a number of other diseases, including type 2 diabetes, high blood pressure, and chronic renal disease.
However, nothing is known about how obesity affects how effectively the Covid vaccination works. But according to our recent research published in Nature Medicine, obesity is associated with a quicker loss of Covid vaccination protection.
We are aware that folks who are obese have a compromised immune response to various vaccinations, such as those for rabies, hepatitis, and the flu.
The SARS-CoV-2 virus, which causes Covid, has a protein on its surface called the spike protein, which is recognized by antibodies produced by Covid vaccinations. The spike protein enables the virus to cling to and infect human cells. If we do get the virus, the immunizations also prepare immune cells called T cells to defend against serious COVID.
Many nations have chosen to offer booster immunizations to sustain immunological protection, especially in susceptible populations, since immunity established after two doses begins to decrease in the months that follow.
Following Covid vaccination, antibody levels may be lower in obese individuals than in the normal population, according to many studies.
We put together a team of researchers from the Universities of Cambridge and Edinburgh earlier in the pandemic to look at how obesity affected vaccine efficacy over time.
The University of Edinburgh team, lead by Aziz Sheikh, reviewed real-time healthcare data for 5.4 million individuals across Scotland using a data platform called EAVE II.
They specifically examined Covid hospitalizations and fatalities among 3.5 million people who had received two doses of the vaccine (from either Pfizer or AstraZeneca).
They discovered that, compared to persons with a BMI in the usual range, people with extreme obesity, which was defined as a body mass index (BMI) above 40, had a 76% greater risk of hospitalization and mortality from Covid following immunization. Additionally, the risk was somewhat elevated in underweight (BMI less than 18.5) and obese (BMI between 30 and 40) individuals.
Following the second vaccine, people with severe obesity started to experience an increased risk of serious illness from breakthrough infections more quickly than people of normal weight did (starting around ten weeks post-vaccination; starting around 15 weeks).
Looking into it further
In order to understand the immunological response to a third dose, or booster, of mRNA Covid vaccinations in individuals with extreme obesity, our research performed trials.
We examined 28 very obese patients at Addenbrooke's Hospital in Cambridge and assessed the quantity and function of their antibodies as well as the number of immune cells in their blood after immunization. We contrasted the outcomes with those of 41 individuals of a healthy weight.
Prior to booster vaccination, antibody levels were comparable in samples from all individuals; however, among those with extreme obesity, the ability of antibodies to operate effectively to combat the virus—known as “neutralisation capacity”—was diminished.
Compared to 12% of participants with a normal BMI, we either couldn't identify or assess neutralization capability in 55% of patients with extreme obesity.
This might imply that Covid vaccinations cause lower-quality antibodies in obese individuals. It's likely that the antibodies can't adhere to the virus as strongly as they do in persons who are of a normal weight.
After a booster, the level of antibody function in obese individuals was raised to that of normal-weight individuals. However, we discovered that B cells, which are in charge of antibody synthesis and immunological memory, grew differently in the first few weeks after vaccination in individuals with obesity.
We observed that in individuals with significant obesity, antibody levels and function fell more quickly after the third dosage when immune responses were measured repeatedly over time.
Why does this matter?
Both the study's portions have certain restrictions. For instance, since BMI data was only gathered once for EAVE II, we cannot exclude out variations in BMI over time. Additionally, the sample size for our comprehensive immunology investigation was very small.
However, in obese individuals, Covid immunity does not seem to be as strong or durable.
These results have significant ramifications since extreme obesity affects 3% of the population in the UK and 9% of the population in the US.
First, for this population, Covid boosters may be very crucial. Our research further emphasizes the necessity for more focused treatments to shield obese patients from harmful COVID.
There is evidence that weight reduction of at least 5% may lower the risk of type 2 diabetes and other metabolic problems associated with obesity. Interventions that may result in a long-term weight loss (such lifestyle changes, weight-loss medications, and bariatric surgery) might also enhance Covid results.
Vaccine responses may also be improved by losing weight, although additional study is needed to confirm this.
