Antibody and T cell responses to Sinopharm/BBIBP-CorV in naïve and previously infected individuals in Sri Lanka

Abstract

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.

Immune Responses Following the First Dose of the Sputnik V (Gam-COVID-Vac)

“…Although 19/25 individuals responded to the N protein of SARS-CoV-2, these responses were of very low frequency and were several folds lower than the responses to S1 subunit. The frequency of N protein speci c ASCs were also several fold lower than what we previously observed for the Sinopharm/BBIBP-CorV, which is an inactivated vaccine and therefore, induces immune responses to the N protein17 . Therefore, these low frequency memory T cell responses are likely to be due to pre-existing cross reactive memory B cell responses to other seasonal coronaviruses and are unlikely to…”

“…Of those who were baseline seronegative, 56/69 (81.2%) responded to RBD of WT, 49/69 (71.0%) to B.1.1.7, 25/69 (36.2%) to B.1.351 and 44/69 (63.8%) to B.1.617.2 (Fig.2A). The RBD HAT titres were signi cantly lower for the WT (p < 0.0001), B.1.1.7 (p < 0.0001), B.1.351 (p = 0.001), B.1.617.2 (p = 0.0003) compared to titres of convalescent sera of naturally infected individuals (n = 36)17 . The mean HAT titres for Gam-COVID-vac were similar to the WT (95.6 vs 94.1), B.1.1.7 (62.9 vs 48.8) and for B.1.617.2 (73.9 vs 70.4), compared to our previously published data following a single dose of AZD1222.…”

“…In comparison, 66/68 (97.1%) who received a single dose of AZD1222 gave a positive response to sVNT assay, with median antibody levels of 69.42 (IQR 54.09 to 81.54 % of inhibition) as previously published 13 . We also compared the ACE2 receptor blocking antibody levels with baseline antibodies of those who were found to be infected, and in another cohort of 36 individuals who had varying severity of natural infection 17 . While the ACE2 receptor antibody levels were similar in the two naturally infected cohorts, the ACE2 receptor blocking antibodies were signi cantly lower in the naïve individuals who received 1 dose of the Gam-COVID-Vac compared to baseline seropositives (p = 0.0003), and those who were naturally infected (p = 0.0009) (Fig.…”

COVID-19 infection among health care workers: Experience in Base Hospital Wathupitiwala, Sri Lanka

“…In the current context, the government of Sri Lanka commenced the national COVID-19 vaccination program following its emergency approval of Oxford-AstraZeneca/ChAdOx1 nCoV-19, Sinopharm/BBIBP-Cor V, and Sputnik-V/Gam COVID-Vac and Pfizer-BioNTech/tozinameran. In addition, Jeewandara et al, 2021 recently showed a high seroconversion rate following two doses of Sinopharm/BBIBP-Cor V in his study (6). However, an in-depth analysis of the clinical data and real-world impacts of COVID-19 vaccines, along with immunogenicity data, is essential to comprehend the real picture in Sri Lanka.…”

“…Subsequently, the fish market-related cluster was linked to almost all the districts, followed by a highly intensified New Year-related outbreak in April that resulted in a substantial degree of community spread (5). The recent rapid surge of infective cases and deaths that occurred in August 2021 had dramatically crippled the health system due to the widespread delta (B.1.617.2) variant (5,6) across the country. However, the true extent of the disease among HCWs has been difficult to determine in Sri Lanka, yet PCR testing from nasopharyngeal swabs is challenging with limited resources.…”