摘要
Background 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. Methods 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), B.1.1.7, B.1.351 and B.1.617.2, 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 weeks and at 6 weeks (2 weeks after the second dose). Results 95% of the vaccinees seroconverted, although the seroconversion rates were significantly lower (p<0.001) in individuals >60 years (93.3%) compared to those who were 20 to 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<0.0001) antibodies to the RBD of WT and B.1.1.7, although there was no difference in antibodies to the RBD of B.1.351 and B.1.617.2 compared to convalescent sera. 27.7% of 46.4% of vaccinees had ex vivo IFNγ and cultured ELISpot responses respectively, and IFNγ and CD107a responses were detected by flow cytometry. Conclusions Sinopharm/BBIBP-CorV appeared to induce high seroconversion rates and induce a similar level of antibody responses against ACE2 receptor, B.1.617.2 and B.1.351 as seen following natural infection.
摘要
Since identification of the first Sri Lankan individual with the SARS-CoV-2 in early March 2020, small clusters that occurred were largely contained until the current extensive outbreak that started in early October 2020. In order to understand the molecular epidemiology of SARS-CoV-2 in Sri Lanka, we carried out genomic sequencing overlaid on available epidemiological data. The B.1.411 lineage was most prevalent, which was established in Sri Lanka and caused outbreaks throughout the country. The estimated time of the most recent common ancestor of this lineage was 10th August 2020 (95% lower and upper bounds 6th July to 7th September), suggesting cryptic transmission may have occurred, prior to a large epidemic starting in October 2020. Returning travellers were identified with infections caused by lineage B.1.258 , as well as the more transmissible B.1.1.7 lineage. Ongoing genomic surveillance in Sri Lanka is vital as vaccine roll-out increases.