India will soon start trials to test the safety, immunogenicity, and efficacy after mixing doses of different brands of Covid-19 vaccines. Some studies in the UK and Spain have shown the mixing of Pfizer and AstraZeneca vaccines to be safe and immunogenic. However, officials in India maintain that though the concept is scientifically feasible, it cannot be allowed without adequate evidence and therefore, a study has to be conducted. The decision has also been endorsed by the NTAGI. The study expected to start soon and likely to take about two months will be conducted by the government in collaboration with vaccine manufacturers.