Question mark over effectiveness of Pfizer-BioNTech COVID-19 vaccine in obese people

A study by a team of researchers based at Istituti Fisioterapici Ospitalieri (IFO) in Rome, Italy, aimed to analyse the antibody response following two doses of the Pfizer/BioNTech COVID-19 vaccine, BNT162B2, in 248 healthcare workers. They also looked to evaluate how the antibody titer in those participants changed in relation to age, gender and body mass index (BMI).

Of the cohort studied, 158 were women (63.7%) and 90 were men (36.3%). The average age was 47 years, with the range going from 23 to 69 years of age. Participants received the first dose of the vaccine at baseline and booster dose at day 21. Blood and nasopharyngeal swabs were collected at baseline and seven days following the second dose.

The antibody titer was found to be higher in young and female participants. A strong correlation of BMI classes with antibody titers was noticed: humoral response was more efficient in the group with under- and normal-weight compared to the group with pre- and obesity participants, said the team led by Aldo Venuti.

The constant state of low-grade inflammation, present in overweight people, can weaken some immune responses, including those launched by T cells, noted the authors, citing previous work in this area. "Moreover, vaccines against influenza, hepatitis B and rabies have shown reduced responses in those who are obese compared with those who are lean."​

These findings from this study​​, which is not yet peer reviewed, imply that females, lean and young people have an increased capacity to mount an antibody‐mediated response compared to males, overweight and the older population, though further studies are needed to corroborate the results, concluded the researchers.

Higher doses or booster doses for obese patients​

“To our knowledge, this study is the first to analyse COVID-19 vaccine response in correlation to BMI,”​ they commented.

Since obesity is a major risk factor for morbidity and mortality for patients with COVID-19, it is mandatory to plan an efficient vaccination program in this subgroup, said the team behind the study.

“Our data stresses the importance of close vaccination monitoring of obese people, considering the growing list of countries with obesity problems.​

“If our data was to be confirmed by larger studies, giving obese people an extra dose of the vaccine or a higher dose could be options to be evaluated in this population.”​

Risk of dying from COVID-19 due to obesity factors 

In July last year, Public Health England estimated​​ that having a BMI of 35 to 40 could increase a person’s chances of dying from COVID-19 by 40%, while a BMI greater than 40 could increase the risk by 90%.

A BMJ report​​ from October 2020 cited comments from Stephen O’Rahilly, director of the Medical Research Council’s Metabolic Diseases Unit at the University of Cambridge who pointed out how two things happen when obesity occurs: “The amount of fat increases, but also you put fat in the wrong places. You put it in the liver and in skeletal muscle. And that disturbs metabolism. The key disturbance is that you get very high levels of insulin in the blood.”​

This disturbance is associated with a range of abnormalities, including increases in inflammatory cytokines and a reduction of a molecule called adiponectin that directly protects the lungs, he said.

Source: medRxiv ​

DOI: https://doi.org/10.1101/2021.02.24.21251664​​

Title: Obesity may hamper SARS-CoV-2 vaccine immunogenicity ​

Authors: A Venuti et al.