Largely coronavirus-free Australia has been heralded globally as a pandemic success story, but it is one of the few rich nations to have an extremely limited vaccination rollout.

So far, just 670,000 doses have been administered in Australia, according to official statistics, far below the initial plan to jab four million people by the end of March.

Morrison said that target had been "dispensed with" months ago, and that strangled exports of three million doses from Europe were "obviously going to impact the early success".

"It's not a race," he said, accusing critics of "wanting to play politics with vaccine and distribution".

Critics have warned that Australia's slow vaccination rate risks new clusters emerging and an indefinite delay in reopening the country's borders.

Richard Holden, an economist at the University of New South Wales, said that Morrison "has to say 'it's not a race'".

"Because if it was, we would have been lapped multiple times and be battling it out for 75th place," he tweeted.

"Of course it's a race—against the virus and outbreaks, and for economic recovery."

Early in the pandemic, Morrison had boasted that Australia would be "at the front of the queue" for vaccines after a slew of deals with pharmaceutical firms AstraZeneca, Pfizer and Novavax.

His government had set an initial target of having all adults fully vaccinated by October.

On Wednesday, Morrison indicated that the target had changed, saying "we are on track for our first dose for everyone by the end of October".

Political finger-pointing

The crisis has resulted in some political finger-pointing, with state authorities on Wednesday angrily rejecting Canberra's claim that they were to blame for the delays.

New South Wales premier Gladys Berejiklian -- an ally in Morrison's conservative Liberal party -- said she was not happy with such "untrue" and "extremely unfair" suggestions.

Queensland premier Annastacia Palaszczuk described them as "outrageous".

Australia has largely avoided widespread coronavirus transmission but has regularly had to scramble to contain outbreaks originating from hospitals and hotel quarantine for overseas arrivals.

Around two million people are currently in lockdown in greater Brisbane -- Australia's third-largest city -- after around a dozen cases were detected.

The country has reported around 30,000 Covid-19 cases in total out of a population of 25 million since the pandemic began -- including those detected in quarantine for overseas travellers.

Authorities are hoping that local production of Oxford/AstraZeneca vaccines will now kick up a gear and provide around one million doses a week.