NEW DELHI: With the country’s apex drug regulator’s expert panel on Covid19 recommending trials to assess the safety and efficacy after mixing Covid vaccines, vaccinologists and health experts pointed out that this may pave the way for a more rational expansion of the inoculation drive.
The subject expert committee on Covid of the Central Drugs Standard Control Organisation had on Thursday endorsed two applications to examine the mixing and matching of Covid vaccines but a final go ahead by the Drug Controller General of India is still awaited.
One of these applications included a submission by the Christian Medical College, Vellore, to study mixing of Covishield and Covaxin in 300 volunteers while Bharat Biotech had sought permission to mix Covaxin with a nasal vaccine still under clinical trial.
“The applications seeking interchangeability of vaccine doses were considered and it was felt that as similar studies abroad have shown very encouraging results, we should also generate our own data,” said a source in the CDSCO. "We are now hoping that the DCGI approves the suggestion and studies kick off soon."
Most vaccines against SARS-CoV-2 are given in two doses, but multiple studies in other countries now back up the idea that mixing the Oxford–AstraZeneca (Covishield in India) and the Pfizer vaccine triggers an immune response similar to, or even stronger than two doses of either vaccine.
Vaccine experts, meanwhile, said that it will be a good move that will help the country be better prepared for the future in case there are more variants of SARS CoV 2 that drive the pandemic.
“This is a good proposition, given the variant strain that has been driving the pandemic are far more dangerous than the original strain,” said a vaccinologist with a government institute in the capital.
He added that there have been apprehensions around wild-type spike-directed vaccines falling short on curbing some of the new variants.
“Combining one vaccine with another attenuated whole virus vaccine in different dose combinations may come out to be a better shield against the variants with spike-directed mutations. But I will recommend a very carefully designed study to examine all this,” the scientist added.
Public health researcher Oommen John stressed that the study should be aiming to reap the benefits of available vaccines, while pointing out that this approach has been well tested in prior epidemics such as Ebola.
“With the fast-emerging variants such as delta. the country needs to be prepared with evidence on potential benefits of immune response and boosting, through the mix and match approach,” he said.
John added that as the currently available vaccines have different efficacy profiles, a question that needs to be addressed is whether there be better protective immunity when vaccines are combined and if so in what order, which one first and which one as the follow on and at what gap should these be administered?