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Safety of the Oxford/AstraZeneca COVID-19 vaccine

Experts have investigated the safety of the vaccine following concerns published by the media

Unplanned learning

This article was correct at time of publishing (April 1). For further news and updates please visit C+D’s COVID-19 hub

The European Medicines Agency’s (EMA) safety committee has confirmed that the benefits of the Oxford/AstraZeneca COVID-19 vaccine still outweigh the risks of developing COVID-19 following its meeting on March 18, 2021.(1)

The EMA’s Pharmacovigilance Risk Assessment Committee, which is responsible for reviewing vaccination data on an ongoing basis, has confirmed that the benefits of the Oxford/AstraZeneca COVID-19 vaccine continue to outweigh the risk of side effects following recent concerns raised about the risk of thrombotic events associated with the vaccine. It said: “The vaccine is not associated with an increase in the overall risk of blood clots in those who receive it.” In its statement, the committee concluded that there is no evidence of a problem relating to specific batches of the vaccine or to any manufacturing sites. It should also be considered that COVID-19 itself is known to cause blood clotting complications that can be fatal.(1)

As of March 16, it was estimated that around 20 million people in the UK and Europe had received the Oxford/AstraZeneca vaccine. The committee reviewed seven cases of blood clots in multiple blood vessels, and 18 cases of blood clots in vessels draining blood from the brain. The safety committee involved experts in blood disorders and worked closely with health authorities such as the UK’s Medicines and Healthcare products Regulatory Agency (MHRA). Overall, it found that there is no increased risk of blood clots with the Oxford/AstraZeneca vaccine compared to that expected in the general population.(1)

The committee’s opinion was that the vaccines proven efficacy in preventing hospitalisation and death from COVID-19 outweighs the extremely small likelihood of developing clotting problems. However, given the small number of severe cases reported, the committee states that patients should be made aware of the remote possibility of such issues occurring, and any patients who suffer symptoms suggestive of blood clotting should seek medical attention immediately. Steps have since been taken to update product information for the vaccine to include additional information on the risks involved.(1)

As with all medicines, close safety monitoring will continue, with additional studies being carried out to provide more laboratory data, as well as real-world evidence. You can find further information on side-effects associated with COVID-19 vaccines by reading the C+D article: What adverse reactions can occur with the COVID-19 vaccines?

Safety concerns

Clinical trial information about the Oxford/AstraZeneca COVID-19 vaccine indicated high efficacy rates, and no safety concerns were raised. The Oxford University/AstraZeneca research teams have been submitting trial data to the MHRA since September 2020 and continual reviews by the regulatory authorities remain positive.(3)

Despite this, several European Union (EU) and non-EU member countries temporarily halted use of the Oxford/AstraZeneca vaccine after reports of blood clots began to circulate as a precaution.(4,5) The reported events were a serious concern that required detailed scientific evaluation.(5) The EMA has now reviewed the cases and states that the benefits of the Oxford/AstraZeneca vaccine outweigh the risks and there is no indication that vaccination is linked to thromboemobolic events. The World Health Organisation has also supported the use of the Oxford/AstraZeneca vaccine.(6)

What does this mean for pharmacy teams?

As a result of the detailed investigation undertaken, a direct healthcare professional communication has been sent to healthcare professionals prescribing, dispensing or administering the vaccine.(7) This communication states that the rare cases of thrombosis and thrombocytopenia have been reported in patients recently vaccinated with the Oxford/AstraZeneca COVID-19 vaccine. However, the number of reported cases is lower than would be expected from the general population. Most of the reports involved women under 55 years of age and occurred within the first 7-14 days following vaccination, although it is thought that this may be linked with the targeted nature of vaccination campaigns within the EU.(1)

Patients should be advised that the Oxford/AstraZeneca COVID-19 vaccine is not associated with an increased overall risk of blood clotting disorders.(1)

Healthcare professionals are advised to be alert for possible cases of thromboembolism, disseminated intravascular coagulation (blood clots in multiple vessels) or cerebral venous sinus thrombosis (blood clots in the vessels draining blood from the brain). Patients that receive the Oxford/AstraZeneca COVID-19 vaccine should be advised to seek medical attention if they develop any of the following symptoms after vaccination:(1)

  • breathlessness
  • pain in the chest or stomach
  • swelling or coldness in a leg
  • severe or worsening headache or blurred vision after vaccination
  • persistent bleeding
  • multiple small bruises, reddish or purplish spots, or blood blisters under the skin.

Patients should also be advised that COVID-19 is such a threat to human life and health that the benefits of receiving the vaccine to prevent it continue to outweigh the risks of potential side effects.

Further information on vaccine administration and safety can be found at the C+D articles: Administration of COVID-19 vaccine in the UK and Latest Advice on COVID-19 vaccines.

Patients can be signposted to and the patient information leaflet for more information.

  1. European Medicines Agency 2021 COVID-19 vaccine AstraZeneca benefits still outweigh risks despite possible link rare blood clots
  2. (2021) Oxford University/AstraZeneca COVID-19 vaccine approved
  3. University of Oxford (2021) USA, Chile and Peru interim trial data show Oxford-AstraZeneca vaccine is safe and highly effective
  4. Henley, J. (2021) The Guardian: EU regulator to report on AstraZeneca COVID vaccine safety
  5. Wise J. (2021) Covid-19: European countries suspend use of Oxford/AstraZeneca vaccine after reports of blood clots. BMJ 2021;372:n699
  6. World Health Organisation (2021) The Oxford/AstraZeneca COVID-19 vaccine: what you need to know
  7. European Medicines Agency (2021) COVID-19 vaccine AstraZeneca: risk of thrombocytopenia and coagulation disorders
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Mr CAUSTIC, Community pharmacist

David i note you wrote about Bill Gates on April fools day . This is for the benefit of anyone who thinks it might be true . Otherwise it will start circulating on social media as fact ! If it is true the stress of pharmacy is getting to you .It is a co-incidence   Do not fill in a yellow card but do  consult your GP . Employers think twice if you need to employ a locum whose mind is receiving 5G and Bill Gates and other voices !  I am available and only receive LBC and PSNC emails , not on 5G

David Moore, Locum pharmacist

Had my second vaccination yesterday. No problems (so far!) First dose gave me a sore arm the following morning but nothing from the second.

However, my 5G reception is now brilliant and I keep hearing voices in my head, mainly Bill Gates'.

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