After further investigating cases of thromboembolic events and other conditions related to blood clots reported after vaccination with Vaxzevria (AstraZeneca), the Pharmacovigilance Risk Assessment Committee (PRAC) of the European Medicines Agency (EMA) has concluded that unusual blood clots with low levels of blood platelets (thrombocytopenia) are very rare side effects of the vaccine. The overall benefits of the vaccine in preventing COVID-19, with its associated risk of hospitalisation and death, outweigh the risks of side effects.
PRAC has concluded today that unusual blood clots with low levels of blood platelets should be listed as very rare side effects of Vaxzevria (formerly COVID-19 Vaccine AstraZeneca).
In reaching its conclusion, PRAC took into consideration all evidence currently available, including the advice from an ad hoc expert group.
EMA is reminding healthcare professionals and people receiving Vaxzevria 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 evidence currently available, specific risk factors have not been confirmed.
People who have received the vaccine should seek immediate medical assistance if they develop symptoms of this combination of blood clots and low levels of blood platelets (see below).
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.
PRAC 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 22 March 2021, 18 of which were fatal. The cases came mainly from spontaneous reporting systems of the European Economic Area (EEA) and the United Kingdom (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.
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.
| Patients should seek immediate medical assistance if they have the following symptoms: |
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| - 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 |
One plausible explanation for the combination of blood clots and low levels of blood platelets is an immune response, leading to a condition similar to one sometimes seen in patients treated with heparin (heparin induced thrombocytopenia, HIT). PRAC has requested new studies and amendments to ongoing ones to provide more information and will take any further actions necessary.
PRAC stresses the importance of prompt specialist medical treatment. By recognising the signs of blood 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 European Union for protection against COVID-19. Studies show that Vaxzevria is effective at preventing the disease. Vaxzevria 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.
Situation in Belgium
In Belgium, no cases of cerebral venous sinus thrombosis with low blood platelets have been reported so far. One case of splanchnic vein thrombosis with low blood platelets, which resulted in death, was reported. This report was investigated in detail. Underlying conditions (confounders) could explain this death.
Information for the general public
- Cases of unusual blood clots with low levels of platelets have occurred in people who received Vaxzevria (formerly COVID-19 Vaccine AstraZeneca).
- The chance that this situation occurs is very low, but you should still be aware of symptoms so you can get prompt medical treatment to help recovery and avoid complications.
- You must seek immediate urgent medical attention if you have any of the following symptoms in the weeks after your injection:
- shortness of breath,
- chest pain,
- leg swelling,
- persistent abdominal (belly) pain,
- neurological symptoms, such as severe and persistent headaches or blurred vision,
- tiny blood spots under the skin beyond the site of injection.
Information for healthcare professionals
- EMA has reviewed cases of thrombosis in combination with thrombocytopenia, and in some cases bleeding, in people who received Vaxzevria (formerly COVID-19 Vaccine AstraZeneca).
- These very rare types of thrombosis (with thrombocytopenia) included venous thrombosis in unusual sites such as cerebral venous sinus thrombosis and splanchnic vein thrombosis as well as arterial thrombosis. Most of the cases reported so far have occurred in women under the age of 60 years. Most cases occurred within two weeks of the person receiving their first dose. There is limited experience with the second dose.
- As for the mechanism, it is thought that the vaccine may trigger an immune response leading to an atypical heparin-induced-thrombocytopenia like disorder. At this time, it is not possible to identify specific risk factors.
- Healthcare professionals should be alert to the signs and symptoms of thromboembolism and thrombocytopenia so that they can promptly treat people affected in line with available guidelines.
- Healthcare professionals should tell people who are receiving the vaccine that they must seek medical attention if they develop:
- symptoms of blood clots such as shortness of breath, chest pain, leg swelling, persistent abdominal pain
- neurological symptoms, such as severe and persistent headaches and blurred vision
- petechiae beyond the site of vaccination after a few days.
- 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.
- Healthcare professionals involved in giving the vaccine in the European Union will receive a direct healthcare professional communication (DHPC). The DHPC will also be published on a dedicated page on the FAMHP and EMA websites.
More information is available on the EMA website.