Comparable neutralization of SARS-CoV-2 Delta AY.1 and Delta in individuals sera vaccinated with BBV152

The recent emergence of the SARS-CoV-2 Variant of Concern, B.1.617.2 (Delta) variant and its high transmissibility has led to the second wave in India. BBV152, a whole-virion inactivated SARS-CoV-2 vaccine used for mass immunization in India, showed a 65.2% protection against the Delta variant in a double-blind, randomized, multicentre, phase 3 clinical trial. Subsequently, Delta has been further mutated to Delta AY.1, AY.2, and AY.3. Of these, AY.1 variant was first detected in India in April 2021 and subsequently from twenty other countries as well. Here, we have evaluated the IgG antibody titer and neutralizing potential of sera of COVID-19 naive individuals full doses of BBV152 vaccine, COVID-19 recovered cases with full dose vaccines and breakthrough cases post-immunization BBV152 vaccines against Delta, Delta AY.1 and B.1.617.3. A reduction in neutralizing activity was observed with the COVID-19 naive individuals full vaccinated (1.3, 1.5, 1.9-fold), COVID-19 recovered cases with full BBV152 immunization (2.5, 3.5, 3.8-fold) and breakthrough cases post-immunization (1.9, 2.8, 3.5-fold) against Delta, Delta AY.1 and B.1.617.3 respectively compared to B.1 variant. A minor reduction was observed in the neutralizing antibody titer in COVID-19 recovered cases full BBV152 vaccinated and post immunized infected cases compared to COVID-19 naive vaccinated individuals. However, with the observed high titers, the sera of individuals belonging to all the aforementioned groups they would still neutralize the Delta, Delta AY.1 and B.1.617.3 variants effectively.

Isolation and characterization of SARS-CoV-2 VOC, 20H/501Y.V2, from UAE travelers

Multiple SARS-CoV-2 variants have been emerged and created serious public health in the affected countries. The variant of Concern associated with high transmissibility, disease severity and escape mutations is threat to vaccination program across the globe. Travel has been important factor in spread of SARS-CoV-2 variants worldwide. India has also witnessed the dreadful effect of these SARS-CoV-2 variants. Here, we report the Isolation and characterization of SARS-CoV-2 VOC, 20H/501Y.V2 (B.1.351), from UAE travelers to India. The virus isolate would be useful to determine the efficacy of the currently available vaccines in India.

Neutralization of B.1.1.28 P2 variant with sera of natural SARS-CoV-2 infection and recipients of BBV152 vaccine

The emergence of new SARS-CoV-2 variants has been a serious threat to the public health system and vaccination program. The variant of concerns have been the under investigation for their neutralizing potential against the currently available COVID-19 vaccines. Here, we have determined the neutralization efficacy of B.1.1.28.2 variant with the convalescent sera of individuals with natural infection and BBV152 vaccination. The two-dose vaccine regimen significantly boosted the IgG titer and neutralizing efficacy against both B.1.1.28.2 and D614G variants compared to that seen with natural infection. The study demonstrated 1.92 and 1.09 fold reductions in the neutralizing titer against B.1.1.28.2 variant in comparison with prototype D614G variant with sera of vaccine recipients and natural infection respectively.

Assessment of immunogenicity and protective efficacy of ZyCoV-D DNA vaccine candidates in Rhesus macaques against SARS-CoV-2 infection

Vaccines remain the key protective measure to achieve herd immunity to control the disease burden and stop COVID-19 pandemic. We have developed and assessed the immunogenicity and protective efficacy of two formulations (1mg and 2mg) of ZyCoV-D (a plasmid DNA based vaccine candidates) administered through Needle Free Injection System (NFIS) and syringe-needle (intradermal) in rhesus macaques with three dose vaccine regimens. The vaccine candidate 2mg dose administered using Needle Free Injection System (NFIS) elicited a significant immune response with development of SARS-CoV-2 S1 spike region specific IgG and neutralizing antibody (NAb) titers during the immunization phase and significant enhancement in the levels after the virus challenge. In 2 mg NFIS group the IgG and NAb titers were maintained and showed gradual rise during the immunization period (15 weeks) and till 2 weeks after the virus challenge. It also conferred better protection to macaques evident by the viral clearance from nasal swab, throat swab and bronchoalveolar lavage fluid specimens in comparison with macaques from other immunized groups. In contrast, the animals from placebo group developed high levels of viremia and lung disease following the virus challenge. Besides this, the vaccine candidate also induced increase lymphocyte proliferation and cytokines response (IL-6, IL-5).The administration of the vaccine candidate with NFIS generated a better immunogenicity response in comparison to syringe-needle (intradermal route). The study demonstrated immunogenicity and protective efficacy of the vaccine candidate, ZyCoV-D in rhesus macaques.