Hyderabad-based Bharat Biotech on Sunday sought DCGI nod to extend the shelf life of its Covaxin. A few months ago Covishield manufacturer Serum Institute of India (SII) too had moved the top drug regulator for a similar request and had got approval too. However, while the DCGI gave nod to SII to extend Covishield shelf life from six to nine months, the WHO has rejected SII’s proposal, citing insufficient data.