Ross Clark

Oxford vaccine gets a boost from US study

Oxford vaccine gets a boost from US study
(Photo by ANDY BUCHANAN/POOL/AFP via Getty Images)
Text settings

The hesitancy of many European countries to use the AstraZeneca vaccine (between bouts of complaining the company hasn’t delivered enough doses) has been widely reported. Less discussed is the delay in US authorities approving the vaccine for use there. But with the reporting of results from a US trial, that should now be a formality. The trial, run by Rochester and Columbia universities, involved 32,449 volunteers in the US, Peru and Chile. Two thirds were given the actual vaccine and the rest a saline placebo. In all, 141 people developed a symptomatic Covid illness. Those who were given the vaccine, however, were found to have their risk of developing symptomatic infection cut by 79 per cent. Their risk of developing serious illness was reduced by 100 per cent.

Importantly, this trial included a large number of over-65s — who made up 20 per cent of the participants. Their risk of developing symptomatic infection was found to be reduced by 80 per cent — in other words, it was just as effective in them as it was in the younger population. This should end the reluctance of some EU countries in giving the vaccine to older age groups, and refutes President Macron’s claim — made without any evidence — that the vaccine was ‘quasi-ineffective’ in the over-65s.

The US trial found no serious side effects. Bearing in mind concerns in Europe, the Independent Data Safety Monitoring Board carried out a specific review into blood clots and found zero increased risk among those who were given the vaccine. It ought to be noted, however, that a trial involving 21,000 people is unlikely to pick up one-in-a-million events. But if there is a risk — and Norwegian doctors continue to insist they have linked cases to the vaccine — it must be very small.

The results of the US trial are better than the initial results of Phase 3 trials in Britain, Brazil and South Africa, which had found the vaccine to have an efficacy of 70 per cent. It is still lower, however, than that reported by the Pfizer and Moderna vaccines which have shown efficacy rates of 95 per cent. But what matters most is the complete absence of serious cases of the disease among people given the AstraZeneca vaccine. Moreover, the US trial gave all participants two jabs, four weeks apart. UK trials, by contrast, have indicated that efficacy increases when the jabs are given 12 weeks apart. That is the vaccination regime being followed in Britain, so it may turn out that vaccinated Brits’ risk of developing symptomatic illness ends up falling by more than 79 per cent.