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Are there other, more serious side effects?

Astra Zeneca COVID-19 vaccine and rare blood clots

A condition involving blood clots and unusual bleeding has been reported extremely rarely after having the Astra Zeneca vaccine. This is being carefully reviewed but the risk factors for this condition are not yet clear.

For people under 40 without underlying health conditions, it is currently advised that it’s preferable to have another COVID-19 vaccine instead of the Astra Zeneca vaccine. For further guidance please see the leaflets on COVID-19 vaccine and blood clotting at:

If you have a history of heparin-induced thrombocytopenia and thrombosis (HITT or HIT type 2), you should receive an alternative COVID-19 vaccine.

If you received a first dose of the AstraZeneca vaccine, you should complete the course with the same vaccine, unless you experience anaphylaxis or an episode of thrombosis combined with thrombocytopenia.

Because of the high risk of complications and death from COVID-19, the Medicines and Healthcare products Regulatory Agency (MHRA), the World Health Organisation and the European Medicines Agency have concluded that the balance is very much in favour of vaccination.

If you experience any of the following from around four days to four weeks after vaccination, you should seek medical advice urgently.

• a new, severe headache which is not helped by usual painkillers or is getting worse

• an unusual headache which seems to get worse when lying down or bending over or may be accompanied by:

• blurred vision, nausea and vomiting

• difficulty with your speech

• weakness, drowsiness or seizures

• new, unexplained pinprick bruising or bleeding

• shortness of breath, chest pain, leg swelling or persistent abdominal pain

Extremely rare reports of capillary leak syndrome have been reported after the AstraZeneca vaccine in individuals with a prior history of this condition. You may be offered an alternative COVID-19 vaccine.

Heart Inflammation

Worldwide, cases of inflammation of the heart (called myocarditis or pericarditis) have been reported very rarely after COVID-19 vaccines. Most of these cases have been in younger men and usually a few days after the vaccination. Most of these people recovered and felt better following rest and simple treatments.

You should seek medical advice urgently if you experience:

• chest pain

• shortness of breath

• feelings of having a fast-beating, fluttering, or pounding heart

If you have had any of the above symptoms after your first vaccination, you should speak to your doctor or specialist before having the second dose.

Reporting side effects

You can report suspected side effects of the COVID-19 vaccine through the Yellow Card Scheme at:

If you do seek advice from a doctor or nurse, make sure you tell them about your vaccination (show them your vaccination card if possible) so that they can assess you properly.