Statistics about the Oxford / AstraZeneca vaccine have made a big impact on the news, with concerns about blood clots forcing many European countries to stop using it.
Then, on Thursday, the European Medicines Agency (EMA) and the UK Medicines and Healthcare products Regulatory Agency (MRHA) announced that there was no increased overall risk of thromboses, but they were continue to look at a rare type of welding associated with low plates. , especially in the brain.
From nearly 12m Oxford / AZ vaccines up to March 7, the UK “yellow card” system has recorded 61,000 reports reporting 228,000 reactions, about twice the rate for the Pfizer / BioNTech vaccine . There have been a large number of immediate side effects such as pain, nausea, fatigue, headache and fever, with other well-known reports including palpitations (1,318), “feeling jittery” (10), “screaming” “(4), chilblains (10), alcohol poisoning (2), increased libido (1), decreased libido (1), and a remarkable report of post – vaccination of a child. But some have been serious incidents, including 289 deaths shortly after the injection, all of which will be carefully examined.
All decisions have a trade value. Both vaccines in the UK have had more than 200 severe allergic reactions (anaphylaxis), which is why we have to sit for 15 minutes after the injection. It is therefore reasonable that, rather than saying that the vaccine is “safe”, the EMA and MRHA emphasize that the benefits of the vaccine outweigh the risks of side effects.
In the UK one of these rare blood reactions has been in a 2m injection. But for every 2 million people in their 50s who get an injection, the mainstream group gets the vaccine, we would now expect to prevent around five deaths a week. The ratio of gain to injury is high, and even higher on mainland Europe as their third wave begins.
The “warning” respite in many countries could mean more delays in vaccinations. France has moved from initially not approving the Oxford / AZ vaccine for people over 65, to stopping for everyone, so far without approving it for children under 55. it would be surprising if people are confused by this. Confidence can break like glass and be difficult to replicate.
• David Spiegelhalter is chairman of the Winton Center for Risk and Evidence Communication in Cambridge. Anthony Masters is a statistical ambassador for the Royal Society of Statistics