There are four possibilities – or possibly a combination of all four. Either more cases are being recorded, as a result of ramping-up of testing; the disease is becoming less virulent; we are getting better at treating it; or the disease has started infecting less vulnerable groups.

There is support for all of those hypotheses. The US has now conducted 29 million COVID-19 tests, more than any other country. Moreover, the number of tests being performed has risen as the epidemic has progressed. The US has now conducted 87,000 for every million population – nearly half as many again as in Germany, a country that has been praised for its testing. Conduct more tests for a disease – especially one in which 80 per cent of infected people are asymptomatic and what is the result? You pick up more cases. A rise in the number of recorded cases does not necessarily mean the number of actual cases is going up – it might simply mean your detection rate is going up.

Is the virus becoming less virulent? There is not of lot of evidence for this, though it is the view of Alberto Zangrillo, a virologist at the San Raffaele Hospital in Milan, who was reported earlier this month saying that the swabs he was taking from patients now showed ‘infinitesimal’ levels of the virus compared with those taken in April. Are we getting better at treating the disease? It would be surprising if we weren’t, given that it is a novel disease and no one at first knew what they were dealing with. Initially, for example, patients were being rushed onto ventilators, a treatment which many hospitals are now avoiding if they can after high mortality rates.