https://www.newsbuyback.com/2021/03/efficacy-cost-manufacturing-%e0%a4%95%e0%a5%87-basis-%e0%a4%aa%e0%a4%b0-covishield-%e0%a4%94%e0%a4%b0-covaxin-%e0%a4%95%e0%a5%80-%e0%a4%a4%e0%a5%81%e0%a4%b2%e0%a4%a8%e0%a4%be-%e0%a5%a4-vaccine/