India has said it will administer homegrown coronavirus vaccine Covaxin in seven more states from Monday as it seeks to inoculate 30 million healthcare workers across the country.

The expansion from the 12 states now administering Covaxin includes the southern state of Kerala, which has a high Covid-19 caseload, and Prime Minister Narendra Modi's home state of Gujarat, the government said, according to Reuters.

Some doctors have expressed doubt about Covaxin, which was approved without efficacy data from late-stage clinical trials. The government says it is safe. The Lancet medical journal said on Thursday the drug produced an immune response in a small group of adults.