FOI release

Freedom of Information request on ages and sexes of individuals who have CVST or other thrombosis-related events with concurrent thrombocytopenia after the second COVID-19 AstraZeneca vaccination (FOI 21-553)

Published 13 August 2021

22nd June 2021 FOI 21/553

Dear

Thank you for your email dated 24th May 2021, where you asked:

“Please provide clarity on the age range and sex distribution of the patients who have been registered as having CVST or other thrombosis-related events with concurrent thrombocytopenia after second vaccination with COV-19 AstraZeneca (Vaxzevria). Please also include fatalities.”

As described in the most recent weekly summary of Yellow Card reporting which is based on information received up to and including 9th June 2021, the MHRA had received Yellow Card reports of 390 cases of major thromboembolic events (blood clots) with concurrent thrombocytopenia (low platelet counts) in the UK following vaccination with COVID-19 Vaccine AstraZeneca. Twenty seven of these events have been reported after a second dose. Of the 390 reports, 207 occurred in women, and 180 occurred in men aged from 18 to 93 years. The overall case fatality rate was 18% with 71 deaths, four of which occurred after the second dose.

Cerebral venous sinus thrombosis was reported in 140 cases (average age 46 years) and 250 had other major thromboembolic events (average age 54 years) with concurrent thrombocytopenia. The estimated number of first doses of COVID-19 Vaccine AstraZeneca administered in the UK by 9 June was 24.6 million and the estimated number of second doses was 17.7 million. The overall incidence after first or unknown doses was 14.8 per million doses. Taking into account the different numbers of patients vaccinated with COVID-19 Vaccine AstraZeneca in different age groups, the data shows that there is a higher reported incidence rate in the younger adult age groups following the first dose compared to the older groups (20.2 per million doses in those aged 18-49 years compared to 10.7 per million doses in those aged 50 years and over). The MHRA advises that this evidence should be taken into account when considering the use of the vaccine. 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.

The overall incidence after second doses was 1.5 per million doses. Taking into account the different numbers of patients vaccinated with COVID-19 Vaccine AstraZeneca in different age groups, the data shows that there is a lower reported incidence rate in younger adult age groups following the second dose compared to the older groups (0.7 per million doses in those aged 18-49 years compared to 1.5 per million doses in those aged 50 years and over). The number of second doses given to those in the 18-49 years age group is estimated to be 4 million while an estimated 13.7 million second doses have been given to patients aged 50+ years. These rates should not be directly compared to the incidence rates reported after the first dose as the time for follow-up and identification of cases after second doses is more limited and differs across age groups. However, the data are reassuring at this stage and suggest that the reported incidence rate following a second dose is smaller than that seen following a first dose. 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.

As with any major new vaccination campaign, the MHRA always develops a proactive vigilance strategy. Through this strategy we are able to rapidly detect, confirm, and quantify any new risks and weigh these against the expected benefits. We can then take any necessary action to minimise risks to individuals. We also work closely with our public health partners in reviewing the effectiveness and impact of the vaccines to ensure the benefits continue to outweigh any possible side effects. On the basis of the ongoing review, the advice remains that the benefits of the vaccine outweigh the risks in the majority of people. Patient safety is our highest priority and vaccines are the best way to protect people from COVID-19. Everyone should continue to get their vaccination when asked to do so unless specifically advised otherwise.

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.

Yours sincerely,

FOI Team, Vigilance and Risk Management of Medicines Division