No proven links with blood clots or anaphylaxis, TGA says based on Australian and European reviews
There is no increased risk of anaphylaxis associated with the Astra Zeneca COVID-19 vaccine, a Therapeutic Goods Administration (TGA) expert review has concluded.
In addition, the TGA says preliminary reviews conducted by the European Medicines Agency (EMA) and the United Kingdom (UK) Medicines and Healthcare products Regulatory Agency (MHRA) have concluded the vaccine is not associated with an increase in the overall risk of blood clots.
The TGA said earlier this week that it had received 19 reports of anaphylaxis nationally, 14 of which followed the Pfizer vaccine and five following administration of the AstraZeneca ChAdOx1-S COVID-19 vaccine. Four cases of blood clots had also been reported in Queensland.
On Thursday 18 March, and independent expert panel reviewed the five reports and information on two additional cases of suspected anaphylaxis linked to the AstraZeneca vaccine. Four reports came from Queensland and one from each of Victoria, NSW and Northern Territory.
The panel found that the information in only one of the reports met the required assessment criteria for anaphylaxis. This individual made a full recovery.
“The panel advised that some of these cases may have represented allergic reactions or immediate stress responses to vaccination that may appear similar to an anaphylactic reaction, with symptoms such as nausea, throat tightness or rapid heart rate,” the TGA said in a statement.
“Although they might not meet the criteria for anaphylaxis, they still need to be monitored and taken seriously”.
The TGA recommends that immunisation providers continue to provide adrenaline where they feel it is clinically required.
The EMA safety committee looking into the AZ vaccine noted there had been a very small number of cases of a rare type of blood clotting disease (disseminated intravascular coagulation) associated with low levels of blood platelets, with or without bleeding, as well as extremely rare cases of clots in the vessels draining blood from the brain (cerebral venous sinus thrombosis, CVST).
“It has not been proven that these cases were caused by the vaccine and a plausible mechanism for how they could have been caused by the vaccine has not been established,” the TGA said.
“These conditions are also sometimes seen in people who have not received a COVID-19 vaccine or other vaccine. The EMA safety committee also noted that COVID-19 disease itself is often associated with serious clotting problems, which can themselves be fatal”.
The EMA found there was no evidence of a problem related to specific batches of the vaccine or to particular manufacturing sites.
The UK MHRA found that “all the available evidence did not suggest common blood clots in veins were caused by the vaccine.
The MHRA is undertaking a detailed review of the five cases of CVST with low blood platelets that occurred in the UK, and also notes that these events can occur naturally”.
Speaking on Sky News, Health Minister Greg Hunt said the review results were “a very important piece of global, medical news”.
“What we see is the European Medicines Agency has made the same conclusions as the Australian TGA, the Australian Chief Medical Officer, the Australian Technical and Advisory Group on Immunisation that AstraZeneca is safe and effective.
We’ve seen it rolled out with over 11 million doses that have been administered in the UK. It’s saving lives and it’s protecting lives and it will do that here in Australia and it will do that around the world. It’s Great news”.