Immune responses to Sinopharm/BBIBP-CorV in individuals in Sri Lanka.
Jeewandara C., Aberathna IS., Pushpakumara PD., Kamaladasa A., Guruge D., Wijesinghe A., Gunasekera B., Tanussiya S., Kuruppu H., Ranasinghe T., Dayarathne S., Dissanayake O., Gamalath N., Ekanayake D., Jayamali J., Jayathilaka D., Dissanayake M., Madusanka D., Jayadas TT., Mudunkotuwa A., Somathilake G., Harvie M., Nimasha T., Danasekara S., Wijayamuni R., Schimanski L., Rijal P., Tan TK., Dong T., Townsend A., Ogg GS., Malavige GN.
As there are limited data of the immunogenicity of the Sinopharm/BBIBP-CorV in different populations, antibody responses against different SARS-CoV-2 variants of concern and T cell responses, we investigated the immunogenicity of the vaccine, in individuals in Sri Lanka. SARS-CoV-2-specific antibodies were measured in 282 individuals who were seronegative at baseline, and ACE2 receptor blocking antibodies, antibodies to the receptor-binding domain (RBD) of the wild-type (WT), alpha, beta and delta variants, ex vivo and cultured IFNγ ELISpot assays, intracellular cytokine secretion assays and B cell ELISpot assays were carried out in a sub cohort of the vaccinees at 4 and 6 weeks (2 weeks after the second dose). Ninety-five percent of the vaccinees seroconverted, although the seroconversion rates were significantly lower (p 60 years (93.3%) compared to those who were 20-39 years (98.9%); 81.25% had ACE2 receptor blocking antibodies at 6 weeks, and there was no difference in these antibody titres in vaccine sera compared to convalescent sera (p = 0.44). Vaccinees had significantly less (p