Even as India's first indigenous coronavirus vaccine Covaxin is entering its third phase of human trials, Bharat Biotech on Monday raised the logistical query on "how to vaccinate 1.3 billion (130 crore) people with two injectable doses. Terming the exercise a "challenge" it also said that work was on single-dose nasal drop vaccine.

Bharat Biotech International Limited (BBIL) Chairman and Managing Director Krishna Ella said the company's Bio-Safety Level 3 (BSL-3) facility currently has limited capacity but hoped to reach one billion (100 crore) doses by next year.