New Delhi: Corbevax, the Covid vaccine currently being used in India for children aged 12-14 years, was approved based on its interim safety and immunogenicity data, the Union Ministry of Health and Family Welfare told the Lok Sabha in a written reply Friday.
Immunogenicity is defined as the ability of any agent that has been introduced into the human body to provoke an immune response.
The ministry was responding to a question raised by Trinamool Congress MP Dipak Adhikari on the availability of safety and efficacy data for the vaccine, and whether it had been peer-reviewed.
“Based on the interim safety & immunogenicity data of Phase II/III clinical trial conducted in subjects of ≥ 5 to <18 (greater than five and less than 18) years age group, Central Drugs Standard Control Organisation (CDSCO), the national regulator, in consultation with subject expert committee (SEC) has granted permission to manufacture SARS-CoV-2 vaccine [CORBEVAX] of M/s Biological E Limited for restricted use in emergency situation in ≥ 12 to <18 (over 12 and less than 18) years age group,” Minister of State (MoS) Dr Bharati Pravin Pawar told the Lower House.
According to the World Health Organization (WHO), vaccine efficacy is “… measured in a controlled clinical trial and is based on how many people who got vaccinated developed the ‘outcome of interest’ (usually disease) compared with how many people who got the placebo (dummy vaccine) developed the same outcome”.
The WHO says that “once the study is complete, the numbers of sick people in each group are compared, in order to calculate the relative risk of getting sick depending on whether or not the subjects received the vaccine. From this we get the efficacy — a measure of how much the vaccine lowered the risk of getting sick. If a vaccine has high efficacy, a lot fewer people in the group who received the vaccine got sick than the people in the group who received the placebo.”
The government’s reply to the MP’s question did not, however, touch upon the efficacy of Corbevax.
Administered through the intramuscular route, with two doses scheduled 28 days apart, Corbevax — manufactured by the Hyderabad-based Biological E in association with the Baylor College of Medicine and Texas Children’s Hospital, US — is a protein subunit vaccine, which introduces a bit of the spike protein of the SARS-CoV-2 virus into the body to generate an immune response.
Spike protein is the protruding part of the coronavirus that allows the pathogen to enter the host cell.
Sidesteps question about peer-review
The government in its reply also did not clarify whether data on the Corbevax vaccine has been peer-reviewed.
In reply to a specific question on this, the government said: “Peer-review of clinical trial results of specific vaccines are usually done by domain knowledge experts and scientists who have developed and manufactured these vaccines or who have knowledge of such vaccines and vaccination process.”
Asked about the position of the National Technical Advisory Group on Immunisation (NTAGI) on the vaccine, the government said: “Government of India has expanded the Covid-19 vaccination to beneficiaries aged 12-14 years from 16 March 2022, on the recommendation of domain knowledge experts.”
The NTAGI is the highest body of experts that evaluates scientific evidence on all vaccines before they are introduced into a national programme.
On a question about whether Corbevax is effective against Omicron, the government said: “Corbevax vaccine has been tested for neutralising antibody (nAb) titers against Wuhan, Delta and Beta variants in its Phase II/III clinical trial & Phase III (immunogenic superiority) clinical trial conducted in the country & it’s reported to be immunogenic.
“The potential impact of Omicron variant on existing countermeasures including vaccine is scrutinised by technical groups worldwide. Vaccines used in National Covid-19 Vaccination Program remain effective to prevent the risk of severity due to Covid-19.”
Omicron is believed to have replaced all other SARS-CoV-2 variants, to become the most dominant one in India currently.
(Edited by Poulomi Banerjee)