Freedom of Information on the risk of ICU admission as a result of COVID19 infection - by age categorisation and riskof developing VITT or CVST specifically as a result of AstraZeneca vaccination (FOI 22/435)
Published 1 June 2022
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FOI 22/435
10th March
Dear Ms Moore,
Thank you for your FOI request, dated 3rd February 2022, where you asked:
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The risk of ICU admission as a result of COVID19 infection - by age categorisation
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The risk of developing VITT or CVST specifically as a result of AstraZeneca vaccination -by age categorisation
The MHRA does not hold the data to provide a response to your first question.
Regarding your 2nd question, the MHRA has continuously and closely monitored events of thrombosis with thrombocytopenia syndrome (TTS). Up to 23 February 2022, 438 Yellow Card reports describing major thromboembolic events (blood clots) with concurrent thrombocytopenia (low platelet counts) following vaccination with COVID-19 vaccine AstraZeneca had been received. Forty-nine of these occurred after a second vaccine dose. In 159 out of the 438 cases, cerebral venous sinus thrombosis (CVST) was reported. By 23 February 2022, 24.9 million first and 24.2 million second doses of the AstraZeneca vaccine were administered in the UK.
Based on the above figures, the overall incidence rate following the first AZ vaccine dose was calculated at 15.6 per million vaccine administrations. Our data indicate that there is a higher incidence rate following the first vaccine dose in the younger adult population (21.4 events per million doses in 18-49 year olds) compared to the older adult population (11.1 events per million doses in individuals aged 50 years and over). The overall incidence of thromboembolic events with concurrent low platelets after second doses was 2.0 cases per million doses.
The MHRA does not hold information on the risk of developing TTS/ CVST cases ‘specifically as a result of AZ vaccination’. It is important to note that the incidence rate above includes events that occurred coincidently, i.e. these would still have occurred had the individual not been vaccinated. The background incidence rate of TTS, i.e. the rate of TTS events occurring in a non-pandemic situation, is not clear. Attempts have been made to determine this estimate; however, the figures vary widely between different EU databases due to challenges associated with the specific aetiology of these events. Therefore, whilst it is considered evident that there is a link between AZ vaccination and very rare cases of TTS, it has not been possible to determine the risk estimates attributable to the vaccine.
For further information, please see the weekly updated coronavirus vaccine Yellow Card reporting.
We apologise for the delay in getting this response to you. If you have a query about the information provided, please reply to this email.
Yours sincerely,
FOI Team,
Vigilance and Risk Management of Medicines Division
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