From research done in Italy, it turns out the great majority of people infected with Covid-19 have no symptoms. Yet through no fault of their own they were a powerful source of infecting others, some of whom were more vulnerable than them.
This finding has serious implications for the UK, and an Italian experiment run by Professor Sergio Romagnani of Florence University has lessons aplenty for our scientific experts and the Government alike. The main message is that blanket testing, something we aren’t doing in the UK, is crucial for ending the lockdown.
Michael Day reports in the BMJ how carrying this out in a completely isolated village of roughly 3,000 people in northern Italy saw the number of people with Covid-19 symptoms fall by over 90% within 10 days.
Vo’Euganeo, a village 50km west of Venice, was closed off by authorities in mid-February, at which point repeat testing of the entire population began. All those with positive tests were quarantined. The number of people sick from Covid-19 fell from 88 to seven in less than 10 days.
In an open letter to the authorities in the Tuscany region, Romagnani wrote that the great majority of people infected with Covid-19 (50-75%) were asymptomatic, but represented “a formidable source” of contagion.
Professor Romagnani has said: “The percentage of people infected, even if asymptomatic, in the population is very high and represents the majority of cases, particularly, but not only, among young people. Isolation of asymptomatics is essential for controlling the spread of the virus and the seriousness of the epidemic.”
He concluded that employing large-scale testing to find and isolate asymptomatic cases, particularly among health workers who might unwittingly pass the virus to colleagues or patients, was a vital strategy in containing the spread of the disease.
So why aren’t we doing this?
Tom Jefferson, a doctor and epidemiologist at the Nordic Cochrane Centre based in the Veneto region, said the Vo’Euganeo study results would have major implications for testing policy if they were representative of Covid-19 elsewhere, despite seeming to contradict a Chinese report suggesting asymptomatic infections don’t appear to be a major driver of transmission.
However, other reports suggest testing on the Diamond Princess cruise ship did find a significant number of symptomless cases and Jefferson is convinced blanket testing should be mandatory.
Jonathan Ball, professor of molecular virology at the University of Nottingham, said that the “prevalence of asymptomatic or mild disease and its role in virus transmission and the potential role of children in driving this pandemic” are among the “key matters that need to be resolved”.
Daily Mirror news