Ross Clark

Bergamo and the enigma of Covid-19

Bergamo and the enigma of Covid-19
Bergamo (photo: Getty)
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There seems to be only one certainty with Covid-19: that every day we will be bombarded with fresh evidence and scientific opinion that is contradictory and leaves us a long, long way from understanding this disease. Just when it seemed that antibody tests were indicating infection rates of no more than 10 per cent in the worst-affected countries and no greater than 20 per cent in the worst-affected cities, along comes a study which points to vast numbers of infections. This morning, the public health agency in the Northern Italian city of Bergamo – the epicentre of the Italian outbreak in March – reports that a random sample of 9,965 residents from the worst-affected areas show the presence of antibodies in a remarkable 57 per cent of cases.

We knew things were bad in Bergamo, but the numbers are on a different scale to those experienced elsewhere. In New York City, for example, sampling suggested that 21 per cent of the population had caught the virus. No less remarkably, the Bergamo study suggested that the infection rate was higher in the general population than it was among healthcare workers, 30 per cent of whom were found to have antibodies to the virus. Bergamo was put into lockdown on 8 March – one of the earliest places in Italy – so the figures do not speak much for the effectiveness of such measures. Somehow, the virus managed to infect a population which was supposed to be in quarantine. Neither do they appear to support the notion that there is a natural limit of around 20 per cent of people who are susceptible to the virus – a figure which has cropped up again and again in places such as the Diamond Princess cruise ship and in New York.

There is more conflicting scientific opinion today on the issue of how much infection is spread by asymptomatic individuals. On Sunday, I reported a study by the Scripps Research Translational Institute in La Jolla, California, which concluded that in at least 30 per cent of cases – and more likely 40 to 45 per cent – the virus was spread by people who were themselves asymptomatic. If that is right it would render ‘track and trace’ systems – on which the government is relying to ease lockdown – pretty well useless, as we would have no way of countering many routes of infection. Yesterday, however, Maria Van Kerkhove, head of emerging diseases and zoonosis at the World Health Organisation, contradicted that, claiming that ‘from the data we have, it still seems to be rare that an asymptomatic person actually transmits onward to a secondary individual’. She didn’t reveal what data she was quoting. The WHO has been a great advocate of test and trace systems.

It doesn’t get any easier for governments trying to follow ‘the science’. It is rather like trying to follow a roomful of household flies buzzing off in all directions. Those of us who are not in government can be thankful we aren’t making the decisions.