LAST UPDATE | 7 Apr 2021

THE EUROPEAN MEDICINES Agency (EMA) has said unusual blood clots should be listed as a “very rare side effect” of the Oxford/AstraZeneca Covid-19 vaccine.

The EMA’s safety committee had considered all the available evidence around the rare instances of unusual blood clots with low blood platelets in people who had received the AstraZeneca vaccine. 

In its conclusion announced today, the committee said it carried out an in-depth review of a number of cases of these rare clot instances reported in the EU.

The National Immunisation Advisory Committee (NIAC) said this evening that its current advice regarding the use of the AstraZeneca vaccine still applies in Ireland. 

“As previously advised, healthcare professionals and vaccine recipients should be informed that very rare, complicated clotting events have been reported in a small number of people who have recently received the AstraZeneca vaccine,” NIAC said in a statement. 

The committee is set to meet to discuss the EMA’s statement and consult with EU colleagues. It will also consider whether any further advice is required. 

The EMA said most of the rare cases reported have occurred in women under 60 years of age within two weeks of their first vaccine dose. 

Specific risk factors have not yet been confirmed. The EMA’s Executive Director Emer Cooke said the benefits of this vaccine in preventing Covid-19 overall outweighs any potential side effects. 

The EMA said people who have received this vaccine should “seek medical assistance immediately” if they develop symptoms of this combination of blood clots and low blood platelets.

These symptoms include: shortness of breath, chest pain, leg swelling, persistent abdominal pain, neurological symptoms such as persistent headaches or blurred vision, and tiny blood spots under the skin beyond the site of injection. 

The EMA said healthcare professionals should tell people receiving the vaccine that they must seek medical attention if they develop these symptoms.

Emer Cooke, EMA's Exec. Director: "The #PRAC, after an in-depth analysis, has concluded that the reported cases of unusual blood clots following vaccination with AstraZeneca #COVID19vaccine should be listed as possible side effects of the vaccine.”

— EU Medicines Agency (@EMA_News) April 7, 2021

The Health Products Regulatory Authority (HPRA) said that as of today, there have been 18 reports of events possibly relating to blood clots following an AstraZeneca vaccine dose. 

None of these are of the nature of the very rare blood clots of concern. 

The HPRA said an additional small number of cases describing low platelet counts have been received and follow-up is ongoing to rule out the presence of blood clots. 

The authority has so far been notified of around 2,800 self-reported suspected side affects associated with the AstraZeneca vaccine. There have been more than 200,000 doses of this vaccine administered so far. 

The EMA said the chance of these rare clots occurring is “very low” but that people should be aware of these symptoms in order to receive prompt treatment if needed. 

“The benefits of the vaccine continue to outweigh the risks for people who receive it. The vaccine is effective at preventing COVID-19 and reducing hospitalisations and deaths,” the EMA said in a statement.

“National authorities may provide additional guidance on the roll out of the vaccine based on the situation in your country.”

The EMA’s Sabine Straus said the currrently available data did not result in a clear indication of specific risk factors. She said this is a “very rare side effect of the vaccine”. 

Straus said one possible explanation is an immune response that leads to a condition similar to those unusual clots with low blood platelets. 

She said the product information for the AstraZeneca vaccine will be amended to include this information following the EMA’s review. 

In a statement this evening, AstraZeneca said it has been “actively collaborating” with regulators to make changes to the product information to include warnings about the rare instances of blood clots.

The statement added that the company is “already working to understand the individual cases, epidemiology and possible mechanisms that could explain these extremely rare events”.