The World Health Organization (WHO) has granted approval for emergency use to India's government-backed Covid-19 vaccine, Covaxin.

WHO says in a tweet it has granted emergency use listing (EUL) to Covaxin (developed by Bharat Biotech), adding to a growing portfolio of vaccines validated by WHO for the prevention of COVID-19.

According to the BBC, the vaccine was approved in India in January while the third phase of clinical trials was still under way, sparking some concern and criticism.

Bharat Biotech, which makes the vaccine, has since published data suggesting 78% efficacy.

Some experts had reportedly pointed to a fast-track approval and incomplete data, but the firm's the chairman, Dr. Krishna Ella, said the vaccine was "200% safe".

The BBC says the WHO's expert panel, which authorizes emergency approvals, had asked for more data last month while examining the application Bharat Biotech had filed in July.

Few countries have recognized Covaxin and India hopes the WHO approval will change that.