Is the AstraZeneca vaccine safe?

Yes, it is very safe.

The Oxford/AstraZeneca vaccine was approved for use after being thoroughly tested on tens of thousands of people. On top of that, up to 12 May over 23.9 million people have now had this vaccine in the UK, the overwhelming majority without any serious side effects or reactions.

The World Health Organization, the medicines regulator in Europe, and the UK’s own medicines regulator have continued to monitor the safety of the vaccine. They have all said that the Oxford/AstraZeneca vaccine  is safe and emphasised that the benefits continue to outweigh the risks.

What side effects does the AstraZeneca vaccine have?

Like all medicines, vaccines can cause side effects. Many people don't get any side effects.

For the Oxford/AstraZeneca vaccine (like the other vaccines), the vast majority of side effects that occur are mild and short-term.

The most common side effects are discomfort at the injection site, or feeling generally unwell, tired, or feverish, or a headache, feeling sick or having joint or muscle pain. You can take paracetamol to treat any of these side effects.

Often side effects are a sign that the vaccine is doing its job: it can happen with many vaccines that some people might feel slightly unwell because their immune system is responding to the protein, but this is not a Covid-19 illness and the vaccine can’t give you coronavirus.

Does the AstraZeneca vaccine cause blood clots?

Up to 12 May there were 309 reports of people developing rare blood clots which were linked to low platelet levels after receiving a first dose of the Oxford/ AstraZeneca vaccine in the UK.

Blood clots after the vaccine are rare. These 309 cases of blood clots are after over 32 million doses of the vaccine. Of the 309 people who developed blood clots, 56 died.

The MHRA has said that while there is stronger evidence of a link between the vaccine and the blood clots, more research is needed. They have emphasised that any risks of the Oxford/ AstraZeneca vaccine continue to outweigh the risks for the vast majority of people.

All the cases of blood clots that the MHRA reviewed were accompanied by abnormally low levels of platelets in the blood. Platelets are involved in blood clotting, and these abnormally low levels can be a sign that your body’s normal clotting mechanisms are not working properly. Some of the blood clots were an unusual type of blood clot in blood vessels that drain blood from the brain called a cerebral venous sinus thrombosis (CVST).

It is possible that an unusual immune reaction triggered by the vaccine could cause this to happen in rare cases and scientists are studying this further. The European Medicines Agency has now listed this as a rare possible side effect of the vaccine.

An early study by the University of Oxford suggests that getting Covid-19 can put you at a much greater risk of developing CVT, than what having any of the vaccines would.

What is the chance of dying from blood clots after having the vaccine?

Even if the Oxford/AstraZeneca vaccine is proven to be the cause of the clots, the rate of death is extremely low – about one in every 425,000 people vaccinated. This needs to be balanced with the known risks of coronavirus causing serious illness (with complications that can include blood clots) and death. The risks of not having the vaccine are much greater than any risks of having it, for you as well as for those around you.

What are the signs of a blood clot? When should I seek help?

• You should call 111 if you experience any of the following symptoms after a few days, and up until four weeks after having the vaccine:
• A severe headache that isn’t getting better, even after painkillers
• A headache that feels worse when you bend over or lie down
• A headache that isn’t normal for you, that occurs with blurred vision, nausea, vomiting, difficulty with your speech, weakness, drowsiness or seizures.
• A rash on your skin that looks like small bruises or blood under the skin
• Chest pain, shortness of breath, leg swelling or stomach pain

Why are people under 40 being offered alternative vaccines?

Analysis on the small number of people who experienced blood clots after getting the Oxford/ AstraZeneca vaccine suggests the risk, while still small, may be higher in younger adults.

The UK’s vaccine advisory body, the JCVI, recommends that previously unvaccinated people under 40 with no underlying health conditions should be offered the Moderna or Pfizer/ BioNTech vaccine if available. In some locations people under 40 may still be offered the Oxford/ AstraZeneca vaccine if that is what is available (as it is easier to transport and store).

The JVCI has said this age group can still choose to have Oxford/AstraZeneca if they want to get vaccinated sooner.

If I had AstraZeneca for my first dose, will I have it again for my second dose?

At present yes - if you had the Oxford/AstraZeneca vaccine for your first dose, you will be offered it again for your second dose, even if you are under 40.

I have a history of blood clots – is the AstraZeneca vaccine safe for me?

Overall, if you have a history of blood clots you can still have the Oxford/ AstraZeneca vaccine. The only people who are advised to have an alternative vaccine are those with a history of heparin-induced thrombocytopenia and thrombosis (HITT or HIT type 2). These are very rare conditions.

There is no evidence that people with a history of blood clots (including deep vein thrombosis, or a clot that leads to a heart attack and stroke) are at increased risk from blood clots caused by the vaccine. If you are in this group, the risk of another blood clot caused by Covid-19 is likely to be far greater than the risk of a blood clot caused by the vaccine. The advice from the government’s Green Book of information on the vaccine is that the Oxford/AstraZeneca vaccine, or any of the available vaccines, are safe.

I’ve heard that the AstraZeneca vaccine thins your blood, could this be true?

No, the AstraZeneca vaccine is not a blood thinner.

Some blood thinning medicines are also called anti-platelet drugs (because they discourage your platelets from sticking together to form a clot), and you may have heard the word platelets in connection with the AstraZeneca vaccine.That’s because a very small number of people who have had this vaccine have developed blood clots and low platelet levels (thrombocytopaenia). This may happen when antibodies that your body produces react to platelets in the blood, but researchers are working to understand this further. This reaction is extremely rare and only happens in a small number of people. It does not mean that the AstraZeneca vaccine will thin your blood.