A nationwide study conducted by the Indian Council of Medical Research (ICMR) during the peak of the second wave of Covid, between April and June, is likely the largest and first nation-wide study of post-vaccination breakthrough infections from India with 677 clinical samples. The subjects had received either Bharat Biotech's Covaxin or Serum Institute of India's version of the Oxford-AstraZeneca vaccine, Covishield. Fewer hospitalisations (9.8 per cent) and deaths (0.4 per cent) were reported in people who experienced breakthrough coronavirus infection, according to the pre-print study.