The has been great alarm over the news that a trial of a vaccine candidate for the coronavirus, from the University of Oxford and drug firm AstraZeneca, has had to be put on hold after a participant developed strange neurological symptoms.
It might seem a cause for concern, but, in fact, it shows that research and development for this vaccine is proceeding exactly as it should do. It also highlights the danger of bypassing the normal stage of large safety trials, as Russia and China seem to be doing with their vaccines.
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We don鈥檛 yet know the full details, but AstraZeneca has said vaccination was paused due to a single 鈥溾�� in a UK participant. According to an anonymous source quoted in , this illness is a condition called transverse myelitis. Rather than a precise diagnosis, transverse myelitis is more of a descriptive term for inflammation of the spinal cord. It can have many causes, but is sometimes triggered by a viral infection, which means it could be linked to the vaccine.
On the other hand, it is also plausible that it isn鈥檛. Many thousands of people have received this vaccine candidate so far, in the UK, US, Brazil and South Africa. Statistically, some of them are bound to develop new illnesses during the trial that are nothing to do with it. All we can do is wait as the researchers investigate.
The alarm is perhaps inevitable given the stakes involved in coronavirus vaccine research. In the UK, the great attention paid to the Oxford vaccine trial seems to partly stem from national pride. But there are nine vaccine candidates around the world that have reached phase III trials: the large, final stage of testing that usually comes before regulatory approval. It is likely that not all of them will reach the clinic.
The standard development process for vaccines and medicines involves testing them in ever-larger trials. Earlier this year, for instance, the AstraZeneca product was successfully , half of whom got the vaccine, with no reported side effects. If it had the capacity to cause a serious side effect in one in 1000 people, or 2000 people, that might not have shown up in a trial that size. That is why it is so important that phase III trials involving thousands of people are done before any vaccine is approved. Even these cannot rule out the risk of very rare side effects emerging later on.
What is more worrying is that some countries seem to be rushing through development of their vaccines before these necessary final-stage trials have been done. Last month, Russia鈥檚 president, Vladimir Putin, said his country had approved a vaccine against the coronavirus. The apparent plan is to start mass immunisation next month. China National Biotec Group, a state-owned drug firm, has reportedly given one of the .
Unfortunately, long before the covid-19 pandemic, anti-vaccine sentiment had been growing in some countries. In the UK, it was largely triggered by unfounded claims that the measles, mumps and rubella vaccine caused autism. In the US, it initially stemmed from concerns over some of the additives in vaccines.
Now anti-vaccine groups swap all kinds of outlandish conspiracy theories online. Even when we do finally get a safe and effective coronavirus vaccine, some nations will have a battle on their hands if they hope to achieve herd immunity by vaccinating enough of their population.
So the prompt action taken by the Oxford vaccine researchers at the first sign of a possible side effect was absolutely necessary. Contrary to what many anti-vax groups say, it shows the immense effort that goes into making sure vaccines are safe.
