Medical experts are worried Australia's success in controlling coronavirus could be put at risk if vaccinations are not rolled out quickly enough.

Prime Minister Scott Morrison is encouraging older Australians to get a vaccine, telling younger people to have the conversation with relatives.

Earlier this week Mr Morrison said he was not focused on people who were vaccine hesitant, instead focusing his efforts on those who would get one.

"I encourage all those that are over 50 to go and get the jab, and particularly if you are over 70 which is our strong focus. I would very much encourage you to do it," he told reporters in Launceston on Friday.

There are fears complacency is creeping into some parts of the community and concerns some older Australians are reluctant to get the AstraZeneca jab because of its link to a small number of rare blood clots.

Cabinet minister Peter Dutton believes the way such cases are being reported could be part of the reason people are choosing to wait for alternative vaccines such as Moderna and Pfizer to arrive later this year.

Mr Dutton said the 24 cases out of 2.1 million doses of AstraZeneca administered in Australia needed to be put in perspective.

"These things happen in a normal season where there's an adverse reaction to someone getting a vaccination, whether it's an adult, someone getting the flu vaccination each year, or if it's a child," he told Nine.

Epidemiologist Catherine Bennett has called for calm after six new cases of rare blood clots were linked to the AstraZeneca vaccine.

Professor Bennett said it was reassuring new cases remained extremely rare, at a rate of between one or two per cent per 100,000.

"We're looking at a range of cases with people with quite mild examples which are being picked up now," she told Seven.

"This is good for stopping it, you want to have that level of follow-up and make sure we are detecting what is going on."

Prof Bennett said most of those who had developed blood clots suffered mild side effects and made a full recovery.

"There have been cases who have been treated outside of hospital," she said.

"They haven't even gone into hospital and were back to work pretty quickly. It's good to know that. I do think it makes people realise this is not always serious."

Union boss Sally McManus warned Australia's health and economic recovery won't be secured while the vaccine rollout stalls and the community receives mixed messages from the government.

Ms McManus told the ABC the government appeared reluctant to launch a major advertising campaign because it did not want to raise expectations they could not meet.

The government says it is spending $40 million on advertising and a campaign targeting older Australians will be released soon.

Australian Associated Press