Beijing, Jun 20 (IANS): More than 1 billion doses of Covid-19 vaccines has been administered in China, as the country is pushing ahead with the largest vaccination drive in its history, according to the National Health Commission (NHC) on Sunday.

It took the country just five days to hit its most recent 100-million dose increase, Xinhua news agency reported citing the NHC as saying.

China accelerated its pace of free Covid-19 vaccinations for the whole nation since late March.

It took China 25 days to climb from 100 million doses to 200 million doses, 16 days to increase from 200 million to 300 million, and six days from 800 million to 900 million.

A total of 21 vaccines have entered clinical trials in China since last year.

So far, four vaccines have been granted conditional marketing approval and three have been authorised for emergency use within the country.

China's nationwide vaccination campaign is open to people aged over 18.

The country has approved the emergency use of domestic inactivated vaccines on people aged 3 to 17.

Detailed policies will be formulated for the inoculation of this age group based on the specific Covid situation.

At least 70 per cent of the target population in China is expected to be vaccinated against Covid-19 by the end of this year, according to Zeng Yixin, deputy head of the NHC.