Neutralization of Delta variant with sera of Covishield vaccinees and COVID-19 recovered vaccinated individuals

Abstract

The recent emergence of B.1.617 lineage has created grave public health problem in India. The lineage further mutated to generate sub-lineages B.1.617.1 (Kappa), B.1.617.2 (Delta), B.1.617.3. Apparently, the Delta variant has slowly dominated the other variants including B.1.617.1 (Kappa), B.1.617.2 (Delta), B.1.617.3. With this, World Health Organization has described this sub-lineage as variant of concern. The high transmissibility associated with Delta variant has led to second wave of pandemic in India which affected millions of people. Besides this, variant of concerns has been reported to show lower neutralization to several approved vaccines. This has led to breakthrough infections after completion of vaccination regimen. There is limited information available on the duration of protective immune response post-infection, vaccination or breakthrough infection with SARS-CoV-2. In this study, we have evaluated immune response in sera of the Covishield vaccinated individuals belonging to category: I. one dose vaccinated, II. two doses vaccinated, III. COVID-19 recovered plus one dose vaccinated, IV. COVID-19 recovered plus two doses vaccinated and V. breakthrough COVID-19 cases. The findings of the study demonstrated that the breakthrough cases and the COVID-19 recovered individuals with one or two dose of vaccine had relatively higher protection against Delta variant in comparison to the participants who were administered either one or two doses of Covishield. Prior vaccination results in less severe disease against subsequent infection provide evidence that both humoral and cellular immune response play an important role in protection.

Serendipitous COVID-19 Vaccine-Mix in Uttar Pradesh, India: Safety and Immunogenicity Assessment of a Heterologous Regime

“…The sera of the heterologous group was efficient in neutralizing VOCs; Alpha, Beta and Delta as we have previously reported with two doses of Covaxin and Covishield 16. 17,18 .…”

Effectiveness of BBV152/Covaxin and AZD1222/Covishield vaccines against severe COVID-19 and B.1.617.2/Delta variant in India, 2021: a multi-centric hospital-based case-control study

“…The VE of two doses of Oxford-ChAdOx1-S against severe infection with the Delta variant in United Kingdom was 67% (Lopez Bernal et al, 2021). Indian studies indicated reduced neutralization capability of BBV152/Covaxin and AZD1222/Covishield vaccine against Delta variant (Yadav et al, 2021;Sapkal et al, 2021). Our study was conducted when B.1.617 lineages were dominating in India (INSACOG, 2021).…”

Design and Immunogenicity of SARS-CoV-2 DNA vaccine encoding RBD-PVXCP fusion protein

“…Despite the unprecedented success in SARS-CoV-2 vaccine development, incorporating S protein from wild type Wuhan-Hu-1 strain, novel strains of SARS-CoV-2 have emerged facilitating mild to moderate escape from humoral immunity, which includes but not limited to B.1.1.7 (UK; alpha variant), B.1.351 (SA; beta variant), P.1 (Brazil; gamma variant), B.1.617.2 (India; delta variant) and recently Omicron (B.1.1.529) with its derivatives. Several studies reported a 2-to 4-fold reduction in neutralization against Delta, a 6-fold or higher reduction in neutralization against Beta, and a 29-fold reduction in neutralization against Omicron for both convalescent and vaccinated individuals 16,17,18 . Despite reduced vaccine efficacy against mutant strains, effectiveness remained high against hospitalization or severe disease 19 .…”