CANBERRA, Jan. 15 (Xinhua) -- A scientist who led the development of the Oxford-AstraZeneca COVID-19 vaccine has warned Australia against delaying its rollout.

The Australian and New Zealand Society for Immunology recently called on the Australian government to pause its planned rollout of AstraZeneca's coronavirus vaccines, saying it may not be effective enough to generate herd immunity to the virus.

In response, head of the Oxford Vaccine Group Andrew Pollard said that the focus should be on the vaccine's ability to prevent serious illness or death from COVID-19 rather than its capacity to stop transmission of the virus.

"Having a supply of vaccines today and getting them into people's arms is what will save lives. That to me has got to be the absolute focus," he said, according to The Sydney Morning Herald on Friday.

"The one hard bit of data we have for all the vaccines is that people who are vaccinated do not end up in hospital from COVID-19 and we've seen that consistently from our trials."

The Australian government has agreed to purchase 53.8 million doses of the Oxford-AstraZeneca vaccine pending approval by the Therapeutic Goods Administration (TGA).

Some experts cited trials of the vaccine that found it was 62 percent effective at preventing COVID-19, compared to about 95 percent for vaccines from Pfizer and Moderna.

Pollard said that the impact of a vaccine could only be determined "when they're in people's arms."

"We don't have any possibility of herd immunity without having high levels of vaccine coverage and nowhere in the world has had that happen yet," he told the Australian Broadcasting Corporation.

Australian Chief Medical Officer Paul Kelly on Wednesday dismissed calls to postpone the rollout, which is set to begin in mid-February.

As of Thursday afternoon, there had been 28,658 confirmed cases of COVID-19 in Australia, and the numbers of locally and overseas acquired cases in the last 24 hours were zero and 10 respectively, according to the latest figures updated on Thursday evening from the Department of Health.