The European Medicines Agency (EMA) safety committee (PRAC) concluded on April 7 that unusual blood clots with low blood platelets should be listed as very rare side effects of Vaxzevria (formerly Covid-19 Vaccine AstraZeneca), the agency said.
EMA head Emer Cooke told a news conference that the safety committee had confirmed that the benefits of the AstraZeneca vaccine in preventing Covid-19 overall outweighed the risks of side-effects.
The vaccine was highly effective in preventing severe cases and hospitalisations, Cooke said.
“The risk of mortality from Covid is much greater than the risk of mortality from these side-effects,” she said.
Cooke said that the possible blood clotting disorder would have to be included in the product information.
PRAC head Sabine Straus said that the clotting disorders were very rare side-effects of the AstraZeneca vaccine.
The committee had not concluded that there were age and gender risk factors.
The EMA said in a statement released before the news conference that in reaching its conclusion, the committee took into consideration all currently available evidence, including the advice from an ad hoc expert group.
EMA is reminding healthcare professionals and people receiving the vaccine to remain aware of the possibility of very rare cases of blood clots combined with low levels of blood platelets occurring within two weeks of vaccination.
So far, most of the cases reported have occurred in women under 60 years of age within two weeks of vaccination. Based on the currently available evidence, specific risk factors have not been confirmed, the EMA said.
Patients who have received the vaccine should seek medical assistance immediately if they have symptoms of this combination of blood clots and low blood platelets, including shortness of breath, chest pain, swelling in your leg, persistent abdominal (belly) pain, neurological symptoms, including severe and persistent headaches or blurred vision, tiny blood spots under the skin beyond the site of injection.
The PRAC noted that the blood clots occurred in veins in the brain (cerebral venous sinus thrombosis, CVST) and the abdomen (splanchnic vein thrombosis) and in arteries, together with low levels of blood platelets and sometimes bleeding.
The Committee carried out an in-depth review of 62 cases of cerebral venous sinus thrombosis and 24 cases of splanchnic vein thrombosis reported in the EU drug safety database (EudraVigilance) as of March 22 2021, eighteen of which were fatal. The cases came mainly from spontaneous reporting systems of the EEA and the UK, where around 25 million people had received the vaccine.
“Covid-19 is associated with a risk of hospitalisation and death. The reported combination of blood clots and low blood platelets is very rare, and the overall benefits of the vaccine in preventing Covid-19 outweigh the risks of side effects,” the EMA said.
EMA’s scientific assessment underpins the safe and effective use of Covid-19 vaccines. Use of the vaccine during vaccination campaigns at national level will also take into account the pandemic situation and vaccine availability in the individual member state.
The EMA said that one plausible explanation for the combination of blood clots and low blood platelets is an immune response, leading to a condition similar to one seen sometimes in patients treated with heparin (heparin induced thrombocytopenia, HIT). The PRAC has requested new studies and amendments to ongoing ones to provide more information and will take any further actions necessary.
The PRAC emphasised the importance of prompt specialist medical treatment.
“By recognising the signs of bloods clots and low blood platelets and treating them early, healthcare professionals can help those affected in their recovery and avoid complications.”
Vaxzevria is one of four vaccines authorised in the EU for protecting against Covid-19. Studies show that it is effective at preventing the disease. It also reduces the risk of hospitalisation and deaths from Covid-19.
As for all vaccines, EMA will continue to monitor the vaccine’s safety and effectiveness and provide the public with the latest information, the agency said.
(Photo: Bulgaria’s Military Medical Academy)
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