FOI release

Freedom of Information request on Covid-19 vaccine AstraZeneca vaccine (FOI 21-395)

Published 28 June 2021

Thank you for your Freedom of Information request, dated 10/04/2021, where you asked for clarification on the following:

‘The government/Medicines and Healthcare products Regulatory Agency (MHRA) are currently saying that there have been around 80 recorded blood clots and 19 related blood clot deaths in the UK from the AstraZeneca vaccine. The government/MHRA data to the 28th March 2021 alone suggests this is hugely inaccurate. Other words for blood clots are embolisms, thrombus and embolus. By searching the latest AstraZeneca adverse reactions report just for these words (to 28th March 2021) we find 934 blood clot events and 59 deaths. Please could you explain why the numbers being reported are so inaccurate and how they are being derived’

To address your first point, as you have rightly pointed out, the most recent guidance specifically concerning the AstraZeneca vaccine and extremely rare, unlikely to occur blood clot events published by the MHRA updated on the 7th April 2021, available here, does detail the recognition of 79 recorded blood clot events and 19 associated with a fatal outcome, up to and including the 31st March 2021. However, it should be noted that this data accounts for reports where blood clotting events have been reported alongside a reaction suggesting concurrent low levels of platelets (thrombocytopenia) experienced by the patient. The published report states these 79 cases as ‘reports of blood clotting cases alongside low levels of platelets following the use of the COVID-19 Vaccine AstraZeneca.’

Whilst there was original concern over all blood clotting events, as noted within the initial government response, here, rigorous scientific review of all the available data at the time suggested that the available evidence didn’t suggest that blood clots in veins (venous thromboembolism) were caused by COVID-19 Vaccine AstraZeneca. Further to this review however, the combination of serious blood clotting events, such as cerebral venous sinus thrombosis (CVST), and concurrent thrombocytopenia was found to be the primary and current safety concern in association with vaccine use as the incidence seen from the available Yellow Card data was noted to be slightly higher than what is normally expected in the general population. This was confirmed following careful and thorough consideration by the Agency alongside specialist input from the Government’s independent advisory body, the COVID-19 Vaccines Benefit Risk Expert Working Group, which includes advice from lay representatives and leading haematologists.

As you will know, the weekly COVID-19 ADR summary alongside analysis prints for each vaccine are published here. It currently pertains to data received up to and including the 28 th April 2021, so provides a more up to date record of the number and type of ADR reports we have received through the Yellow Card scheme than the aforementioned government response to the ongoing safety review for serious blood clotting and thrombocytopenia events.

To note, direct comparison of the summary provided in the weekly summary and the analysis prints is not possible. This review includes reports of CVST or other thrombo-embolic events with concurrent thrombocytopenia. Yellow Card reports may contain more than one reported reaction and the analysis prints are listed by individual reactions rather than whole reports. Therefore, summing the reactions listed in the prints will not equate to the total cases included within this summary.

I hope the information provided is helpful, but if you are dissatisfied with the handling of your request, you have the right to ask for an internal review. Internal review requests should be submitted within two months of this response; and can be addressed to this email address. Yours sincerely, FOI Team, Vigilance and Risk Management of Medicines Division