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Obesity undermines COVID-19 vaccines

Obesity undermines COVID-19 vaccines

In a recent article published within the journal Nature Medicine, researchers compare the effectiveness of coronavirus disease 2019 (COVID-19) vaccines between obese and individuals with a traditional body mass index (BMI) ranging between 18.5 and 24.9 kg/m2.

Study: Accelerated waning of the humoral response to COVID-19 vaccines in obesity. Image Credit: SUPERMAO / Shutterstock.com


Current estimates indicate that 3% of the UK and 9% of the USA population is taken into account obese. Obesity can increase the chance of developing many comorbidities, comparable to type II diabetes (T2D) and chronic kidney diseases.

In the course of the COVID-19 pandemic, severe obesity was identified as a critical risk factor for developing severe COVID-19. Since COVID-19 vaccines reduce the chance of significant COVID-19, there may be an urgent need to evaluate the consequences of obesity on responses to messenger ribonucleic acid (mRNA) and adenoviral vector vaccines.

Several studies have suggested that obesity impairs immune responses to many vaccines, comparable to rabies, influenza, and hepatitis vaccines. The truth is, some studies have shown that COVID-19 vaccines elicit lower antibody titers in obese people as in comparison with the overall population, thus makes these individuals high-risk to severe COVID-19.

In regards to the study

On this study, researchers investigate the sturdiness of protection conferred by COVID-19 vaccination in obese individuals. To this end, fully vaccinated obese adults 18 years or older were identified from Scotland’s Early Pandemic Evaluation and Enhanced Surveillance of COVID-19 (EAVE II) surveillance platform. This study cohort received not less than two doses of mRNA-1273, BNT162b2, or ChAdOx1 nCoV-19 vaccines between December 8, 2020 and March 19, 2022.

About 500,000 people were obese, 98,000 of whom were severely obese with BMI of over 40 kg/m2 and experienced severe COVID-19 outcomes. The second study cohort comprised 41 and 16 individuals with normal BMI who were evaluated six months after the first vaccination series and after the third-dose vaccination, respectively.

The EAVE II platform allowed the researchers to look at the impact of the study participants’ clinical and sociodemographic characteristics, including COVID-19 history, time elapsed since receipt of the second and third vaccine doses, and dominant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant on the time of vaccination.

For most people, BMI measurements were available of their the first care record. If missing, the researchers calculated BMI data using a median of 10 least squares regressions with all other independent variables covered as predictors.

The frequency and rate for each 1,000 person-years of severe COVID-19 outcomes were determined. The association between sociodemographic and clinical aspects and study outcomes as rate ratios (RRs) with 95% confidence intervals (CIs) was also determined using generalized linear models (GLMs). Adjusted RRs (aRRs) were also obtained after adjusting for all confounders like gender and sex.


On this study, the researchers prospectively measured temporally-varying humoral immune responses elicited against the authentic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strain in vaccinated individuals with severe obesity and normal BMI.

Individuals with higher BMI, including those that were considered obese and severely obese, were at an increased risk of severe COVID-19, including hospitalization and mortality. Severely obese individuals also had fewer neutralizing antibody titers six months after primary vaccination than those with a traditional BMI.

The altered antibody kinetics reflect the reduced affinity or dissociation between anti-receptor binding domain (RBD) antibodies and neutralizing potential, which has been previously observed in severe COVID-19 patients in other settings, comparable to after influenza vaccination.

Nonetheless, peak antibody levels were higher in severely obese individuals than those with a traditional BMI. Thus, vaccine delivery didn’t fail in obese individuals as a result of short needle length, which suggests that a hard and fast dosing schedule is more appropriate for COVID-19 vaccination of all individuals, including severely obese people.


The study findings demonstrated that COVID-19 vaccines don’t fail to focus on neutralizing spike epitopes in individuals with severe obesity. As an alternative, the shortage of high-affinity antibodies is related to the relative reduction within the neutralizing capability of vaccine-induced antibodies.

There’s growing evidence that weight reduction of even 5% could reduce the chance of many metabolic complications arising from diseases like T2D that always affect obese individuals. Thus, lifestyle modifications and interventions like bariatric surgery that help achieve weight reduction could similarly mitigate COVID-19 outcomes. 

Further studies should determine whether hyperglycemia modulates the chance of poor COVID-19 outcomes in individuals with severe obesity. Additional research can be needed to analyze whether weight reduction has useful effects on COVID-19 vaccine-elicited humoral immunity.

Even though it could also be difficult for healthcare providers to implement vaccine programs, administering additional booster doses more ceaselessly in obese individuals who rapidly lose vaccine-elicited humoral responses over time could help this high-risk population achieve durable protection against severe COVID-19.

Journal reference:

  • Van der Klaauw, A. A., Horner, E. C., Pereyra-Gerber, P. et al. (2023). Accelerated waning of the humoral response to COVID-19 vaccines in obesity. Nature Medicine. doi:10.1038/s41591-023-02343-2


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