Impaired humoral and cellular response to primary COVID-19 vaccination in patients less than two years post allogeneic bone marrow transplant.
Murray SM., Barbanti M., Campbell C., Brown A., Chen L., Dhanapal J., Tseu B., Pervaiz O., Peters L., Springett S., Danby R., Adele S., Phillips E., Malone T., Amini A., Stafford L., Deeks AS., Dunachie S., Klenerman P., Peniket A., Barnes E., Kesavan M.
Allogeneic transplant recipients (HCT) remain at high risk of adverse outcomes from COVID-19 and emerging variants. The optimal prophylactic vaccine strategy for this cohort is not defined. T-cell mediated immunity is a critical component of graft-versus-tumour effect and in determining vaccine immunogenicity. Using validated anti-spike IgG and spike specific IFNγ ELISpot assays we analysed response to a two-dose vaccination schedule (either BNT162b2 or ChAdOx1) in 33 HCT recipients ≤2 years from transplant, alongside vaccine matched healthy controls (HC). After two vaccines, infection naïve HCT recipients had a significantly lower rate of seroconversion compared to infection naïve healthy controls (25/32 HCT vs 39/39 HC no responders) and had lower spike specific T-cell responses. HCT Patients who received BNT162b2 had a higher rate of seroconversion compared to ChAdOx1 (89% versus 74%) and significantly higher anti-S IgG titres (p = 0.022). Spike specific T cell responses were seen after one vaccine in HC and HCT patients. However, two vaccines enhanced spike specific T-cell responses in HC but not in the majority of HCT patients. These data demonstrate limited immunogenicity of two-dose vaccination strategies in HCT recipients, bolstering evidence of the need for additional boosters and /or alternative prophylactic measures in this group.