Good News: ` Covaxin' trials show vaccine is safe, immunogenic

Developed by India's leading drugmaker `Bharat Biotech', the result of the vaccine was published on medrxiv.org.

It said that the vaccine did not show any major adverse reaction among the volunteers. The vaccine was well tolerated in all dose groups with no vaccine-related serious adverse events. Robust humoral and cell-mediated responses were observed in the Algel-IMDG recipients.

The most common adverse event was pain at the injection site, which resolved spontaneously. The overall incidence rate of local and systemic adverse events in this study was 10%-20% in all vaccine treated arms, which is noticeably lower than the rates for another SARS-CoV-2 vaccine platform candidates and comparable to the rates for other inactivated SARS-CoV-2 vaccine candidates.

BBV152 commonly known as Covaxin is a whole-virion, inactivated SARS-CoV-2 vaccine. The candidates were formulated with two adjuvants: Algel (alum) and Algel-IMDG, an imidazoquinoline class molecule (TLR7/TLR8 agonist abbreviated as IMDG) adsorbed onto Algel.

Three vaccine formulations were prepared as follows: 3 µg with Algel-IMDG, 6 µg with Algel- IMDG, and 6 µg with Algel. The placebo group contained only a sterile phosphate-buffered solution and Algel. The vaccine was provided as a sterile liquid that was injected through the intramuscular route at a volume of 0.5 mL/dose in a two-dose regimen with a 14- day interval. This accelerated schedule was chosen given the context of the ongoing pandemic. Both the vaccine and control were stored between 2°C and 8°C.

The company said one participant was screened on July 25 and vaccinated on July 30. Five days later, the participant reported fever and headache (initially reported as a solicited adverse event), and on August 8 was found to be positive for SARS-CoV-2 (by a nucleic acid test).

The symptoms were initially mild in nature, which the onset of relapsing fever requiring admission to the hospital on August 15. The participant had stable vitals (except body temperature) during hospitalization and did not require supplemental oxygen. The participant was discharged on August 22 following a negative nucleic acid result.

Researchers at Bharat Biotech said the event was not causally associated with the vaccine. No other symptomatic SARS-CoV-2 infections were reported between day 0 and 75.

Researchers noted the first phase has few limitations. "First, as this is an interim report, we are not reporting any data on the persistence of vaccine-induced antibody responses or safety outcomes. Second, the results reported here do not permit efficacy assessments. Third, the evaluation of safety outcomes requires more extensive Phase 3 clinical trials," said the researchers at Bharat Biotech.