Adverse reactions to COVID vaccines are rare — here’s how the TGA monitors for anything wrong



The rollout of the AstraZeneca vaccine in Europe has hit a speed bump, with several nations suspending its rollout after a small number of recipients experienced blood clots.

That’s despite several global medical bodies, and the Australian Government, maintaining the vaccine is safe and that there is no proof the vaccine increases the risk of clotting.

But people feeling unwell or developing symptoms after receiving a vaccine — more commonly known as an adverse event — is a normal part of any medical rollout, and monitoring them can actually demonstrate that a vaccine is safe.

Here’s how Australia keeps tabs on vaccine safety.

Does Australia release information about adverse events?

Yes it does, and not just for coronavirus vaccines.

A person administers a vaccine
So far Australia has received 730 reports of adverse events, most of them mild.(ABC Alice Springs: Mitchell Abram)

The Therapeutic Goods Administration (TGA) maintains a database of adverse event reports, which are made public 90 days after being submitted to the body.

But as the COVID-19 vaccine rollout continues, the TGA has begun releasing weekly updates on the number of adverse reactions reported in Australia.

The latest report, released yesterday, shows that of 164,437 vaccinations in Australia, there were 730 reports of adverse events.

Most adverse events after the COVID vaccine are mild

It’s important to note that while 730 adverse events have been reported, that doesn’t mean the vaccine caused every one of them.

Every day, a certain number of people will experience a range of unexpected medical ailments, and so when hundreds of thousands of people are vaccinated, it only makes sense that some people will experience unrelated symptoms shortly after being vaccinated — they were likely to get sick anyway.

Dr Nigel Crawford from the Murdoch Children’s Research Institute said it was important to investigate all reports to determine whether there was a link to the vaccine, or whether it was just coincidence.

Some symptoms — like anaphylactic allergic reactions — are easy for doctors to link to the vaccine and protect against, while Dr Crawford said others “could be happening by chance alone”.

According to the latest TGA report, the most common adverse events reported were mild and included:

  • headache;
  • nausea;
  • dizziness or feeling faint; and
  • injection site reaction.

Particular attention is also being paid to a small number of more serious events, including six cases of suspected anaphylaxis, three reports of facial weakness, and one report each of seizure and stroke.

The number of anaphylactic reactions in Queensland in recent days led to health authorities urging people with a history of strong allergic reactions to “hold off getting the vaccine”.

Does an adverse event mean a vaccine is dangerous?

The AstraZeneca vaccine made headlines in recent days when a string of European countries halted its rollout, after a small number of people developed blood clots after being vaccinated.

But Dr Crawford, who is also director of Victoria’s vaccine adverse event program SAEFVIC, explained that when large numbers of people were vaccinated, that background rate of illness — people who were going to get sick anyway, regardless of vaccination — had to be factored in.

He said in clinical trials of 24,000 participants, the control group of people who did not get the AstraZeneca vaccine developed more blood clots than those in the arm of the study that did receive the vaccine.

A close up shot shows the label on the vial.
When millions of people are vaccinated, some adverse events are to be expected.(Reuters: Andreas Gebert)

“There were four blood clots … in the vaccine arm and eight in the non-vaccine arm, so very small numbers, but comparing those two arms there was no evidence of increased risk in those who received the vaccine in the phase 3 trials,” he said.

The Australian Government is still confident the AstraZeneca vaccine is safe, and TGA boss John Skerritt said his agency’s job was “differentiating between what is just frankly bad luck, the natural frequency of these things happening, and whether it is a cause and effect of the vaccine”.

The TGA also says that seeing a large number of adverse event reports should not discourage people that a vaccine is safe.

“Furthermore, the number of reports alone cannot be interpreted or used to reach conclusions about the existence, severity, frequency, or rates of problems associated with vaccines.

“The data should not be used to make decisions about the medicines or vaccines people take.”

How do I report an adverse event?

In Australia, anyone can report an adverse event after using a medicine, vaccine or medical product.

If you experience an event, you can make a report to the TGA, or your doctor may do so on your behalf.

According to the TGA, most of the adverse event reports it receives are from pharmaceutical companies and medical device suppliers, but health professionals and consumers can also make reports.

If you as a consumer want to make a report, you can do so on the TGA website, but it’s important that if you experience any serious reaction you also speak to your doctor.

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