The occurrence of serious blood clots after receiving the Oxford Astra Zeneca Vaccine vaccine is extremely rare (4 cases per million vaccines given in the UK). The cases that have occurred have been between 4 days and 2 weeks after having the vaccine. The risk of dying is around 1 in a million. This is about the same level as the risk of dying in an accident on a 250mile road journey (BBC News – AstraZeneca Vaccine: How do you weigh up the risks and benefits?)
For those aged over 30 the benefits of having the vaccine still outweigh these small risks. If you are aged below 30 and have already had your first dose then please attend when invited for the second dose, unless you had any serious side effects, for instance blood clot or pin prick bruising away from the site of the vaccine. If you have any doubts do not hesitate to consult your surgery.
If you are under 30 and have not received your first vaccine dose yet, then you will be offered a different vaccine from the Oxford Astra Zeneca. Due to the limits on vaccine availability this may result in a delay in getting the vaccine or having to travel further to receive it. The numbers of blood clots occurring after the Pfizer vaccine appear no different to what we would expect in an unvaccinated population.
If you wish to read more about these issues please see the resources below:
BBC News: Weighing up the risks and benefits: https://www.bbc.co.uk/news/explainers-56665396
PHE (Public Health England) leaflet on risks of clots in relation to Covid vaccine: https://www.gov.uk/government/publications/covid-19-vaccination-and-blood-clotting
Risk benefit ratios for different age groups, from University of Cambridge: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/976877/CovidStats_07-04-21-final.pdf
MHRA (Medicines and Healthcare products Regulatory Agency) statement on 7th April: https://www.gov.uk/government/publications/use-of-the-astrazeneca-covid-19-vaccine-jcvi-statement/jcvi-statement-on-use-of-the-astrazeneca-covid-19-vaccine-7-april-2021