Antigen specific T cells in people with obesity at five months following ChAdOx1 COVID-19 vaccination

People with obesity (PWO) face an increased risk of severe outcomes from COVID-19, including hospitalisation, ICU admission and death. Obesity has been seen to impair immune memory following vaccination against influenza, hepatitis B, tetanus, and rabies. Little is known regarding immune memory in PWO following COVID-19 adenovirus vector vaccination.

We investigated SARS-CoV-2 specific T cell responses in 50 subjects, five months following a two-dose primary course of ChAdOx1 nCoV-19 (AZD1222) vaccination. We further divided our cohort into PWO (n = 30) and matched controls (n = 20). T cell (CD4⁺, CD8⁺) cytokine responses (IFNγ, TNFα) to SARS-CoV-2 spike peptide pools were determined using multicolour flow cytometry.

Circulating T cells specific for SARS-CoV-2 were readily detected across our cohort, with robust responses to spike peptide stimulation across both T cell lines. PWO and controls had comparable levels of both CD4⁺ and CD8⁺ SARS-CoV-2 spike specific T cells. Polyfunctional T cells - associated with enhanced protection against viral infection - were detected at similar frequencies in both PWO and controls.

These data indicate that PWO who have completed a primary course of ChAdOx1 COVID-19 vaccination have robust, durable, and functional antigen specific T cell immunity that is comparable to that seen in people without obesity.