Ross Clark

The risks of a failed Chinese vaccine

The risks of a failed Chinese vaccine
Photo by PETER PARKS/AFP via Getty Images
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Huge stock has been placed in the development of a vaccine for Covid-19, with the Prime Minister suggesting this week that the disease will not be properly defeated without one. The government has held out on the idea of a vaccine being available as early as September.

So how are things coming along in the real world? Ten days ago the first results from a human trial of a Covid-19 vaccine – developed by Chinese company CanSino Biologics were published in the Lancet. The researchers, from the Jiangsu Provincial Centre for Disease Control and Prevention in Nanjing, reported an immunological response in most of the 108 people given the vaccine. But they were not able to assess how effective it would be in preventing infection, as the level of antibodies required to prevent infection is not known. They also reported adverse reactions in 81 per cent of those taking part – mostly mild cases of muscle pain and fever – rising with the size of the dose received. Nine people, however, developed a severe fever.

Now, reaction to the trials is coming in from other scientists – who are less than impressed. Matti Sällberg, professor and vaccine researcher at the Department of Laboratory Medicine at the Karolinska Institute in Stockholm, tells a Swedish newspaper: 'The saddest thing is that the level of neutralizing antibodies is quite low'. There is a difference, he says, between antibodies that can only bind to the virus and neutralizing antibodies that stop it functioning. Only between 50 and 75 per cent of those in the trial developed levels of neutralising antibodies that are likely to be sufficiently high in number to prevent infection.

Hildegund Ertl, from the Wistar Institute in Philadelphia, said the results were 'a little disappointing'. Especially worrying, she noted, was that the oldest participants in the study – those between 45 and 60 – were the least likely to develop neutralizing antibodies. As we know, the risk of dying or developing serious symptoms from Covid-19 rises sharply with age. There would be limited use for a vaccine which, say, didn’t work in the over-70s – although it could be of some use among healthcare workers.

The CanSino vaccine is only one of 120 vaccines under development, many on an unusually accelerated timetable. Others may be better. But it is a reminder that we cannot take a vaccine for granted – and we cannot rely on one as a strategy for getting out of a lockdown which is hugely-damaging economically and in other medical aspects.