FOI release

Freedom of Information request about AstraZeneca vaccines and blood clots in women (FOI-21-411)

Published 28 June 2021

Thank you for your email dated 13th April 2021, where you asked:

1. How many women under the age of 50 were vaccinated with Astra Zeneca COVID 19 vaccination?

2. How many women who received AstraZeneca vaccination were on contraceptives?

3. How many of the women who received AstraZeneca Vaccination had a blood clot?

4. How many women who received Astra Zeneca vaccination had a blood clot and were on contraceptives?

5. How many women under the age of 50 were vaccinated with Astra Zeneca COVID 19 vaccination?

6. How many women who received AstraZeneca vaccination were on contraceptives?

Firstly, please be assured that the MHRA take into account the different numbers of patients vaccinated with COVID-19 Vaccine AstraZeneca in different age groups during assessment and our evidence-based decision making. However, Public Health England hold this information and have published interactive graphs and tables on the number of people who have been vaccinated which is available here: https://coronavirus.data.gov.uk/details/vaccinations. Please contact them directly if you require a further breakdown: https://www.gov.uk/government/organisations/public-health-england.

1. How many of the women who received AstraZeneca Vaccination had a blood clot?

2. How many women who received Astra Zeneca vaccination had a blood clot and were on contraceptives?

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 low platelets (thrombocytopenia) was found to be the primary and current safety concern in association with vaccine use. The most recent guidance specifically concerning the AstraZeneca vaccine and extremely rare, unlikely to occur blood clot events with concurrent thrombocytopenia, published by the MHRA and updated on the 7th April 2021, is available here.

The MHRA publishes a weekly summary of Yellow Card reporting, which can be found here. In this publication, you will find the specific information you have requested surrounding these case reports, including a breakdown of the sex of these patients. Up to 28 April 2021, the MHRA had received Yellow Card reports of 141 cases of major thromboembolic events (blood clots) with concurrent thrombocytopenia (low platelet counts) in women in the UK following vaccination with COVID-19 Vaccine AstraZeneca.

There is now some evidence that the reported incidence rate is higher in females compared to men, although this is not seen across all age groups, and the difference remains small. These reports have also been analysed by the Government’s independent advisory body, the COVID-19 Vaccines Benefit Risk Expert Working Group, which includes lay representatives and advice from leading haematologists. On the basis of this ongoing review, the advice remains that the benefits of the vaccine outweigh the risks in the majority of people.

A total of 15 cases have been reported where the patient is reported to be using an oral contraceptive. Oral contraceptives can be a risk factor for blood clots in the veins which is not usually associated with low platelet counts. Based on the limited cases, oral contraceptives have not been linked to vaccine-associated blood clots occurring with low platelet counts.

Dr June Raine, MHRA Chief Executive, said:

“Over 44 million doses of vaccines against COVID-19 have now been administered in the UK, saving thousands of lives through the biggest vaccination programme that has ever taken place in this country.

“No effective medicine or vaccine is without risk. These specific kinds of blood clots with low platelets reported following COVID-19 Vaccine AstraZeneca remain extremely rare and unlikely to occur. The benefits of the vaccine continue to outweigh the risks for most people.

“It is still vitally important that people come forward for their vaccination when invited to do so. “We ask anyone who suspects they have experienced a side effect linked with their COVID-19 vaccine to report it to the Coronavirus Yellow Card website.”

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 the date of this response; and can be addressed to this email address.

FOI Team

Vigilance and Risk Management of Medicines Division

Medicines and Healthcare Products Regulatory Agency 10 South Colonnade, Canary Wharf, London E14 4PU