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Safety and immunogenicity clinical trial of an inactivated SARS-CoV-2 vaccine, BBV152 (a phase 2, double-blind, randomised controlled trial) and the persistence of immune responses from a phase 1 follow-up report

Our take —

The best hope for overcoming COVID-19 epidemic is the development of efficient vaccines. This study, available as a preprint and thus not yet peer reviewed, showed that this whole inactivated SARS-CoV-2 virion vaccine (manufactured by Bharat Biotech) is safe and can induce significant immune responses against the virus. In addition, the data showed that this vaccine induces immune response against multiple viral components including the spike protein, the primary target for the vaccines currently approved for emergency use. However, a phase 3 clinical trial is needed to test the efficiency of this vaccine in preventing COVID-19.

Study design

Randomized Controlled Trial

Study population and setting

This is data from the phase 2 clinical trial for the SARS-CoV-2 vaccine BBV152, a whole inactivated virion formulated with an adjuvant to enhance the immune response (manufactured by Bharat Biotech). The study included 380 healthy volunteers between ages 12- 65 years recruited from 11 centers across India. The participants were screened for previous SARS-CoV-2 infection and were randomly assigned to receive one of two vaccine formulations at days 0 and 28. Side effects of the vaccine were monitored for one week after vaccination and immune response was assessed for four weeks after the second dose of the tested vaccine. The study also included the assessment of the vaccine immunogenicity in 198 participants who were included in the phase 1 clinical trial, along with their controls.

Summary of Main Findings

The study found that the vaccine induced minor side effects including fever, chills, aches, malaise and weakness in about 10% of the participant. No severe or life-threatening adverse reactions were reported. The vaccine induced antibodies that can bind to the SARS-CoV-2 virus in over 98% and 92% of the participants receiving the high and low doses, respectively. The authors showed also that the whole inactivated virion induced immune memory cells, suggesting possible longer-term protection of this experimental vaccine.

Study Strengths

The current study has the advantage of including a relatively large number of participants for a phase 2 clinical trial across many centers in India and simultaneously testing two different formulations. The study also included children and teens 12 years and older, compared to Pfizer and Moderna vaccines that are approved for adults above 16 and 18 years respectively. Most of the front runner vaccines focus on targeting SARS-CoV-2 spike protein. The current study tested a vaccine prepared from a whole inactivated virion and showed some evidence of inducing immune response toward the other viral proteins as well. However, it is not clear if targeting other viral proteins can provide any further protection against SARS-CoV-2 infection.

Limitations

This is a phase2 clinical trial so does not present any data on vaccine efficacy. In addition, the study was conducted solely in India and there is no data about ethnic backgrounds of the participants.

Value added

The study showed a whole inactivated virion vaccine against SARS-CoV-2 is safe and induces an immune response. While this is not the first inactivated vaccine that was tested, considering the wide spread of COVID-19 in the world and current vaccine shortage, any effective vaccine can help mitigate the consequences of this disease world-wide.

This review was posted on: 14 January 2021