Oxford/AZ vaccine linked to 242 rare bloods clots in the UK: alternative recommended for people younger than 40

Simon Collins, HIV i-Base

On 7 May 2021 the UK Government recommended that adults aged under 40 years old should preferably use alternatives to the Oxford/AZ vaccine against COVID-19. [1]

This was based on a risk:safety analysis by the UK MHRA linked to rare complications of serious blood clots and age. Detailed information on these and other side effects were included in a detailed MHRA safety report. [2]

By 28 April 2021, the UK Yellow Card Scheme had received 54139 cards for Pfizer, 160543 for Oxford/AZ, 683 for Moderna and 574 where the vaccine make was not specified. For the two most widely used vaccines, Pfizer and Oxford/AZ, there were approximately 3 to 6 cards per 1000 doses.

These reports included 242 cases of major thromboembolic events (blood clots) with concurrent thrombocytopenia (low platelet counts) following the Oxford/AZ vaccine, of which 49 were fatal.

This was after approximately 22.6 million first doses and 5.9 million second doses.

Demographics included 141 cases in women (32 fatal) and 100 in men (17 fatal). Age of cases ranged from 18 to 93 with number of reports/fatalities by age: 18–39 (55/14), 40–59 (106/22), 60–79 (61/12), 80–99 (6/1) and unknown (14/0). Six fatalities were after the second dose.

Cerebral venous sinus thrombosis was reported in 93 cases (average age 47 years) and 149 had other major thromboembolic events (average age 55 years) with concurrent thrombocytopenia.

The reports also includes all deaths following all recent vaccinations, evaluating likely cause as many of these were in older people with complex comorbidities.

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Official comments focused these serious reactions being very rare events. Also, that on a population level the risks are lower than those of having a serious outcomes in the event of COVID-19.

This missed the point, from a community perspective, that many of these individuals could have continued to avoid SARA-CoV-2 through continued isolation and other safety measures – and that they engaged in the vaccine programme for personal and community prevention.

The new advice includes circumstances when the risks from COVID-19 are higher in some people under 40 where using the Oxford/AZ is still recommended, especially if supply issues limit access to alternatives.

Anyone who experiences any of the following symptoms four days after vaccination is recommended to promptly seek medical advice.

• A severe, persistent headache.
• Blurred vision.
• Shortness of breath.
• Chest pain.
• Leg swelling.
• Persistent stomach/abdominal pain.
• Unusual bruising or red/purple pinpoint spots beyond the injection site where the vaccine is given.
• Neurological symptoms such as weakness in the legs or seizures.

References

1. UK Government. Use of the AstraZeneca COVID-19 (AZD1222) vaccine: updated JCVI statement. (7 May 2021).
   https://www.gov.uk/government/publications/use-of-the-astrazeneca-covid-19-vaccine-jcvi-statement-7-may-2021/use-of-the-astrazeneca-covid-19-azd1222-vaccine-updated-jcvi-statement-7-may-2021
2. MHRA. Coronavirus vaccine – weekly summary of Yellow Card reporting. (6 May 2021).
   https://www.gov.uk/government/publications/coronavirus-covid-19-vaccine-adverse-reactions/coronavirus-vaccine-summary-of-yellow-card-reporting

This report was first posted on 9 May 2021.