Many of the same stocks buoyed by the Trans-Tasman travel bubble have taken a tumble as Australia’s vaccine rollout descends into chaos.

Travel brokers, airports, and airlines were all subdued on Friday amid concerns over the safety of the AstraZeneca vaccine for under 50s, the effect on the nation’s COVID vaccination timeline, and what a delay would mean for the eventual opening of borders.

Flight Centre fell 2.6 per cent to $18.44, Webjet lost 2.5 per cent to $5.40, Corporate Travel Management dropped 3.1 per cent to $18.74, and Hellowowrld shed 2.3 per cent to $2.13.

Sydney Airport lost 1.6 per cent to $6.10, Auckland International Airport was 0.7 per cent lower at $7.05.

Qantas was slightly higher at $5.43 and Air New Zealand also rose, up 1.1 per cent at $16775.

The Federal government on Thursday night decided to make Pfizer the preferred coronavirus vaccine for people aged under 50 after medical experts expressed concerns about rare blood clots potentially linked to the AstraZeneca vaccine.

Australia had previously bought 20 million doses of the Pfizer vaccine but was relying more heavily on the AstraZeneca product.

CSL is manufacturing 51 million AZ doses in Melbourne. The company said it is “committed to meeting its contracted arrangements with the Australian Government”.

CSL shares fell 1.2 per cent to $262.62 in afternoon trade.

Prime Minister Scott Morrison this afternoon said the government has secured 20 million more Pfizer doses, doubling the number the nation will buy. He said these should arrive by the fourth quarter of 2021.

It remains unclear what this means for the vaccination timeline. When asked this afternoon whether he could give people certainty that all adult Australians would have at least one dose by Christmas, the Prime Minister said he wasn’t in a position yet to be able to do that.

Health Minister Greg Hunt said Pfizer vaccinations would expand in April, significantly expand again in May and from July there is expected to be a “near-doubling”.

Asked whether CSL should switch to making the Novavax vaccine instead, Dr Brendan Murphy said Australia still needs significant quantities of AstraZeneca to protect people aged over 70 and finish the program already started.

He said the government was in discussion with CSL about whether it could produce other vaccines but, for now, it could only make one type at a time.

Australia’s doses of Novavax are expected to start arriving from overseas between July and September.

Meanwhile, state and federal leaders have asked the medical expert panel to come up with thresholds for how much of the population would need to be vaccinated for Australia to start travelling overseas and return without having to go into hotel quarantine, and whether travel bubble arrangements can be set up with other low-risk countries.