This week marks one year since the first West Australians were given COVID vaccines and now — more than 4.3 million doses later — 96% of our population aged 12 and over are double-jabbed.
And this week a clearer picture has emerged around the safety of the vaccine that threatened to derail the rollout in the middle of last year, when there was a media frenzy over the rare risk of blood clots from the AstraZeneca vaccine.
AZ’s Vaxzevria vaccine started the rollout as the vaccine of choice in Australia because it could be easily manufactured here, but authorities were left scrambling in April after the country started seeing cases of an extremely rare blood clotting disorder linked to the jab.
Newspapers around the country ran front-page headlines and half-page photos of bloodied gauze warning of the risks to younger people.
The risk of dying from the disorder was considered to be less than one in a million, but the rare cases, which were more common in younger people, prompted changes in the age groups recommended for the jab, first to age 50 and above, and eventually to 60 years and above.
And despite thousands of people receiving the jabs without incident, public confidence in the AZ vaccine had been eroded so much in all age groups that by October last year WA was administering just 12 doses a week.
UK studies shed some light
Now that millions of people around the world have had the AZ vaccine, two studies from the UK have provided more precise results on the risks of blood clotting events following vaccination.
Confirming what many health experts argued all along, the studies found that the risk of blood clots from the AZ vaccines was “extremely small.”
In one study, the researchers found that the increased risk of rare blood clots after the vaccine was between 0.9–3 per million people, a risk they said was small compared with the vaccine’s effect in reducing COVID-19 harm.
They analysed the electronic health records of 46 million adults living in England, of whom 21 million were vaccinated during the study time span, from December 2020 to March 2021.
A second study found an increased risk of rare blood clots in the brain that was equivalent to one additional event per 4 million people vaccinated. And the authors said these risks occurred only in people under the age of 70 and that the increase in risk was extremely small.
The researchers suggested more work needed to go into providing the public with more information and context about risks from vaccines.
“This evidence may be useful in risk-benefit evaluations for vaccine-related policies, and in providing quantification of risks associated with vaccination to the general public,” the researchers said.
Currently, the vaccines registered for use in Australia are Comirnaty (Pfizer), Vaxzevria (AstraZeneca), Spikevax (Moderna) and Nuvaxovid (Novavax).