The AstraZeneca coronavirus vaccine has been provisionally approved for use in Australia, paving the way for locally manufactured doses to be rolled out in early March.
It is the second COVID-19 vaccine to be provisionally approved by the Therapeutic Goods Administration, following the Pfizer vaccine, which is already in rollout for priority injections next week.
The AstraZeneca vaccine will be added to those priority rollouts once approved, Health Minister Greg Hunt told reporters on Monday, prior to the regulator's announcement on Tuesday.
The TGA has given provisional approval of the doses for use in immunisation of adults 18 years and older.
Two doses are required, with 12 weeks the recommended interval between the first and second dose. However, if that is not possible due to imminent travel, cancer chemotherapy or major elective surgery, a minimum interval of four weeks can be used.
"TGA's regulatory approval allows the second dose to be administered from four to 12 weeks after the first," a TGA spokesperson said.
Adjunct professor John Skerritt, who leads the Therapeutic Goods Administration, said Australia was only the second country to be able to approve the AstraZeneca vaccine without using emergency measures.
The decision to vaccinate elderly patients over 65 years of age should be made on case-by-case basis, the TGA advised, with consideration of age, co-morbidities and their environment. There were no safety concerns in that age group were identified in clinical studies or in overseas rollouts.
"Our analysis of the data gives us no reason to suspect that the vaccine would not be fully efficacious in older groups," Professor Skerritt said.
He said the UK experience, where the vaccine has been in use in elderly people for more than a month, had seen good results in the rollout.
Professor Skerritt addressed concerns the AstraZeneca vaccine was not as efficacious as the Pfizer vaccine, saying the data showed it was 100 per cent effective in preventing serious illness and death.
"Frankly, there's not a difference when you go into the real world whether something is 82 per cent or 90 per cent. I would emphasise a lot of the discussion on numbers is not particularly relevant."
Due to the long interval between the two shots, Professor Skerritt said many people would find their scheduled time for their COVID-19 vaccines would cross over with their flu vaccinations. It was recommended there was two weeks between the COVID-19 and flu vaccinations, but people won't need to wait the full 12 week interval before getting their flu jab.
Prime Minister Scott Morrison rejected a suggestion Australia's approval process for vaccines had been too slow.
"There has been no slow approval process. This has been, I think, the most efficient and timely process that the TGA has ever undertaken for any vaccine," he said.
"And they've done it in a way which has cut no corner, ensured every inquiry that they would have undertaken in relation to a vaccine would have been undertaken. And that was the safest way to conduct that process and to arrive where we're at today."
Mr Morrison said Australia's success in suppressing case numbers had given the regulator "space" to go through the full process.
Labor continued to press for details about the booking system and state and territory distribution of vaccine doses. Labor's spokesperson Mark Butler said the vaccine rollout should already be well under way.
"In the EU, UK, USA and Canada, once the vaccines were approved by their regulators, injections were being administered in less than a week," Mr Butler said.
"In Australia, the Pfizer vaccine was approved more than three weeks ago, on January 25, and we are still waiting for the first jab."
Further information from ongoing clinical trials and additional monitoring is expected in coming months.
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