Latest studies conducted by the ICMR have highlighted that mixing doses of the homegrown vaccines, Covishield and Covaxin could scale up immune response remarkably well.

from Times of India https://timesofindia.indiatimes.com/life-style/health-fitness/health-news/covid-vaccine-mixing-covaxin-and-covishield-vaccines-is-safe-and-effective-finds-icmr-study/photostory/87106153.cms