New Delhi, Jan. 25 -- India's drug regulator has signalled zero-tolerance for polio-related risk, turning down a proposal by National Dairy Development Board's (NDDB) subsidiary Indian Immunologicals Ltd (IIL) to start human trials of its 'six-in-one' paediatric vaccine over concerns it could undermine the country's polio-free status, according to two government officials and documents reviewed by Mint.

The Central Drugs Standard Control Organisation's (CDSCO) decision, linked to the use of the China-sourced poliovirus antigens highlights how public-health security and biosafety considerations matter the most, even as vaccine makers push to introduce next-generation combination shots in a market immunizing tens of millions of children ea...