Endocrine Abstracts

Introduction: Obesity and diabetes are the known risk factors for severity and susceptibility to severe COVID-19 with a poor prognosis. However, there is limited evidence for the implications and association of metabolic factors on COVID-19 vaccination.

Methods: We systematically searched PubMed/Medline and Cochrane library till January 28, 2022, using: (“diabetes OR BMI OR weight OR glucose OR obesity OR metabolic” and “COVID OR Coronavirus OR SARS-Cov-2” and “vaccine OR immunization OR vaccination”). Two independent researchers assessed the literature and conducted the review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines for Scoping Reviews (PRISMA-ScR).

Results: We evaluated four studies (3 from Italy) with cumulative 1380 patients. The mean number of patients was 345 (±521, minimum 21, maximum 1123). One study (n=84) was only among healthcare workers. COVAC-DM cohort study suggests that humoral immune response to COVID-19 vaccination in diabetes is age dependent but is independent of type of diabetes and glycaemic control. CAVEAT study suggests that hyperglycaemia at the time of vaccination worsens the immunological response and, achieving adequate glycaemic control during the postvaccination period improves the immunological response. Evaluation of the protocols suggests that patients with higher BMI ≤ 30 kg/m² are significantly under-represented in most of the trials. Modulation of the diet to hypocaloric, very-low-carbohydrate diet one week before the mRNA vaccine and blood glucose reduction has a significant positive corelation on the adaptive humoral (anti-SARS CoV-2 S antibodies) and cell-mediated responses (IFN γ). Higher waist circumference, smoking, systemic hypertension and dyslipidaemia are independent confounding variables that lead to lower antibody titres. Diabetes and metabolic risk factors can modulate the immunogenicity of COVID-19 vaccine. Omission or under-representation of participants with higher BMI may cause poorer vaccine coverage for people with higher weight and contribute to greater health inequities.

Discussion: Obesity and hyperglycemia are associated with a reduced adaptive response to a COVID-19 mRNA vaccine. However, weight loss and metabolic−glycemic improvement may reverse the effect. Inclusion of higher BMI individuals in vaccine trials would yield a comprehensive evidence and help mitigate health inequities and potentially add value for substantial subgroup analysis based on the metabolic parameters and appropriately titrate vaccine dose regimes or earlier vaccine boosters, evaluate safety, and ensure equitable protection for higher weight people against COVID-19.