Adar Poonawalla's Serum Institute of India (SII), the maker of coronavirus vaccine Covishield in India, has reportedly been served a legal notice by AstraZeneca over vaccine supply delays. The news emerged a day after Mr Poonawalla admitted in an interview to NDTV that existing production capacity to manufacture Covishield, one of the two vaccines being administered in India, is "very stressed, to put it frankly".