NEW DELHI: No vaccine for respiratory diseases has a 100% efficacy and ones with a 50-100% efficacy may be approved for use against the Covid-19 pandemic, Indian Council for Medical Research (ICMR) director general Dr Balram Bhargava said even as he added that maximum efficacy will be sought.
“No vaccines for respiratory diseases have 100% efficacy. WHO says a vaccine should have three things — safety, immunogenicity (the ability of a foreign substance to trigger an immune response) and efficacy. WHO has said a vaccine with 50% efficacy can be accepted. We are aiming for 100%, but the vaccine’s efficacy would be anywhere between 50-100%,” Bhargava said.
The Oxford vaccine candidate has shown promise in early phases of trial conducted in UK. The trials showed the vaccine to be safe and capable of inducing an immune response. Regulatory authorities say the locally developed candidates also have potential as they are simpler compositions and safety has been ensured.
The comment comes a day after drug regulator, Central Drugs and Standard Control Organisation, issued a draft guidance note for Covid-19 vaccines that suggested researchers may not necessarily look for the preventive capacity of a candidate, and settle for one that protects a person from developing severe infection.
In a draft regulatory guidance note on vaccine development, the drug regulator said it plans to approve Covid-19 vaccines that can provide immunity to at least 50% of the participants in Phase 3 clinical trials. So far, the trials of leading vaccine candidates have offered more encouraging results, particularly with the administration of a second shot.
“To ensure that a widely deployed Covid-19 vaccine is effective, the primary efficacy endpoint estimate for a placebo-controlled efficacy trial should be at least 50%,” CDSCO said in its draft regulatory guidelines for vaccine development, with special consideration for Covid-19 vaccine issued on Monday.
The CDSCO’s draft is in line with guidelines framed by WHO and US FDA.
Currently, there are three vaccines undergoing human trials in India, while the one developed by Russia is also likely to apply for trial permissions soon. The furthest of these vaccines in human trials are Serum Institute of India’s vaccine, which was jointly developed by AstraZeneca and University of Oxford and is currently undergoing Phase 3 trials in India. The other two vaccines in human trials are Bharat Biotech’s candidate developed with ICMR and that of Zydus Cadila.