AstraZeneca shake-up: who gets it now, who doesn’t and what does it mean for Australia’s vaccine rollout?

Australia has undertaken the second major shake-up of its Covid-19 vaccination program in three months, prompted by concerns the AstraZeneca vaccine can cause blood clots in rare cases.

What happened?

On Thursday, Australian health authorities advised that AstraZeneca’s coronavirus vaccine is no longer recommended for people aged 50 to 59, meaning they will instead be given Pfizer vaccines.

This follows a move in April when the Australian Technical Advisory Group on Immunisation (Atagi) advised that the AstraZeneca jab was not recommended for those aged 16 to 50.

Why?

The guidance has changed because of “a higher risk and observed severity” of the blood clot syndrome in 50- to 59-year-olds than reported internationally and initially estimated in Australia, Atagi said in a statement.

From early April to 16 June, 60 cases of confirmed or probable blood clots have been reported in Australia, including seven in the past week in people aged 50 to 59.

The rate of clots in that age group has risen to 2.7 per 100,000 AstraZeneca vaccine doses – very close to the risk for those under 50 (3.1 per 100,000) and almost double the risk for those aged 60-69 (1.4 per 100,000).

How bad are the blood clots?

Atagi says thrombosis and thrombocytopenia syndrome (TTS) is a “serious condition” that “appears to be more severe in younger people”.

The overall case fatality rate in Australia is 3%, as two people have died of the total 60 cases of TTS. This is lower than has been reported internationally. Atagi attributes this to “increased detection due to heightened awareness, as well as early diagnosis and treatment”.

The chief medical officer, Paul Kelly, said that 55% of the 60 cases have left hospital. “Some remain in hospital and some are in ICU.”

Why are over-60s still getting AstraZeneca?

Atagi considers the benefit of vaccination with AstraZeneca outweighs the risk of TTS in people aged 60 and above – both because of a lower incidence and severity of blood clots, and because “the benefits of receiving a Covid-19 vaccine are greater than in younger people”.

“The risks of severe outcomes with Covid-19 increase with age and are particularly high in older unvaccinated individuals,” it said.

What if I’ve already taken the first dose of AstraZeneca?

People who have had their first dose of AstraZeneca without any serious adverse events should receive the second dose.

“The risk of TTS following a second dose of … AstraZeneca is much lower than the risk following a first dose,” Atagi said.

The UK has reported 23 TTS cases in 15.7 million people after receiving a second dose, an estimated rate of 1.5 per million second doses (compared to a reported risk of 14.2 per million first doses in the UK).

Kelly also said there was “very little evidence that it is either safe or effective” to mix and match vaccines by taking one dose of AstraZeneca and the second of Pfizer.

What will this do to the rollout?

The inability of people aged 50 to 59 to take AstraZeneca will increase demand for Pfizer, with a total of 2.1 million people in that age group now eligible for Pfizer who weren’t previously.

That will likely mean longer waits for other adults seeking Pfizer, which is already more limited in supply than AstraZeneca.

Australia is domestically producing up to 1m doses of AstraZeneca a week. On Thursday, the health minister, Greg Hunt, said Australia would receive 1.7m Pfizer doses in June, increasing to 2.8m in July.

Australia has ordered a total of 40m Pfizer doses, but the majority are due to be delivered in the final three months of the year.

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Pfizer is currently available through some commonwealth and state clinics, but not GPs. This will create a chokepoint in the system until 1,300 GPs are able to dispense Pfizer by the end of July.

On Thursday the Covid-19 taskforce commander, Lt Gen John Frewen, said this was a “relatively minor adjustment” to the program that would take “a couple of weeks” to adjust.

Hunt said that Australia was still on track “to offer every Australian a vaccine who is eligible during the course of 2021”.

One upside to the announcement is that people aged 50 to 59 who may have been hesitant to take AstraZeneca may now be more willing to get the Pfizer vaccine.

What if I still want AstraZeneca?

Atagi advises that AstraZeneca can be used in adults aged under 60 years for whom Pfizer is not available, where “the benefits are likely to outweigh the risks for that individual and the person has made an informed decision based on an understanding of the risks and benefits”.

In practice, it can be harder to get an AstraZeneca vaccine if you are in the age groups for which it is not recommended – although some under-50s have done so notwithstanding the warning applied in April.