A study on mixing Covishield and Covaxin, the two main vaccines used in India's COVID-19 vaccination programme, has been given the go-ahead by the Drugs Controller General Of India (DCGI).
This study and its clinical trials will be conducted by Vellore's Christian Medical College.
"Permission has been granted for a research study by CMC Vellore (Tamil Nadu) on mixing of vaccines doses," Dr VK Paul, NITI Aayog Member (Health), said during a press briefing on Tuesday.
A Subject Expert Committee of the Central Drugs Standard Control Organisation (CDSCO) had recommended conducting the study on July 29.
This study will be different from the one by the Indian Council of Medical Research (ICMR), which said mixing the two Covid vaccines elicited better safety and immunogenicity results.
The mixing of doses had raised considerable anxiety.
The study conducted on individuals in the northern state of Uttar Pradesh in India received Covishield as the first dose followed by inadvertent administration of Covaxin as the second dose at an interval of six weeks.
A total of 18 participants were in the heterologous group. However, two participants were unwilling and were excluded. Among them, 11 were male, and seven were female with a median age of 62 years.
The ICMR said the study suggested immunization with a combination of an adenovirus vector platform-based vaccine followed by an inactivated whole virus vaccine was not only safe but also elicited better immunogenicity.
"We did a comparison with heterogeneous group and homologous group, we found better immune response, if somebody gets Covishield first and Covaxin second that it gives better immunity. This is the first study on a combination of Adenovector and whole variant vaccines," Dr Samiran Panda, Head of Epidemiology and Communicable Diseases, ICMR, said.
However, the top medical body added that more detailed and in-depth research must be done on the limitations, as the study is done merely on 18 participants.