Safety and immunogenicity trial of an inactivated SARS-CoV-2 vaccine-BBV152: a phase 1, double-blind, randomised control trial

Ella, R.; Mohan, K.; Jogdand, H.; Prasad, S.; Reddy, S.; Sarangi, V. K.; Ganneru, B.; Sapkal, G.; Yadav, P.; Panda, S.; Gupta, N.; Reddy, P.; Verma, S.; Rai, S.; Singh, C.; Redkar, S.; Gillurkar, C. S.; Kushwaha, J. S.; Rao, V.; Mohapatra, S.; Guleria, R.; Ella, K.; Bhargava, B.

Background: BBV152 is a whole-virion inactivated SARS-CoV-2 vaccine formulated with a TLR 7/8 agonist molecule adsorbed to alum (Algel-IMDG). Methods We conducted a double-blind randomized controlled phase 1 clinical trial to evaluate the safety and immunogenicity of BBV152. A total of 375 participants were randomized equally to receive three vaccine formulations (n=100 each) prepared with 3 g with Algel-IMDG, 6 g with Algel-IMDG, and 6 g with Algel, and an Algel only control arm (n=75). Vaccines were administered on a two-dose intramuscular accelerated schedule on day 0 (baseline) and day 14. The primary outcomes were reactogenicity and safety. The secondary outcomes were immunogenicity based on the anti-IgG S1 response (detected with an enzyme-linked immunosorbent assay [ELISA] and wild-type virus neutralization [microneutralization and plaque reduction neutralization assays]). Cell-mediated responses were also evaluated. Results: Reactogenicity was absent in the majority of participants, with mild events. The majority of adverse events were mild and were resolved. One serious adverse event was reported, which was found to be unrelated to vaccination. All three vaccine formulations resulted in robust immune responses comparable to a panel of convalescent serum. No significant differences were observed between the 3-g and 6-g Algel-IMDG groups. Neutralizing responses to homologous and heterologous SARS-CoV-2 strains were detected in all vaccinated individuals. Cell-mediated responses were biased to a Th-1 phenotype. Conclusions BBV152 induced binding and neutralising antibody responses and with the inclusion of the Algel-IMDG adjuvant, this is the first inactivated SARS-CoV-2 vaccine that has been reported to induce a Th1-biased response. Vaccine-induced neutralizing antibody titers were reported with two divergent SARS-CoV-2 strains. BBV152 is stored between 2{degrees}C and 8{degrees}C, which is compatible with all national immunization program cold chain requirements. Both Algel-IMDG formulations were selected for the phase 2 immunogenicity trials. Further efficacy trials are underway.