A study in Vò, which saw Italy’s first death, points to the danger of asymptomatic carriers

The small town of Vò, in northern Italy, where the first coronavirus death occurred in the country, has become a case study that demonstrates how scientists might neutralise the spread of Covid-19.

A scientific study, rolled out by the University of Padua, with the help of the Veneto Region and the Red Cross, consisted of testing all 3,300 inhabitants of the town, including asymptomatic people. The goal was to study the natural history of the virus, the transmission dynamics and the categories at risk.

The researchers explained they had tested the inhabitants twice and that the study led to the discovery of the decisive role in the spread of the coronavirus epidemic of asymptomatic people.

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When the study began, on 6 March, there were at least 90 infected in Vò. For days now, there have been no new cases.

“We were able to contain the outbreak here, because we identified and eliminated the ‘submerged’ infections and isolated them,” Andrea Crisanti, an infections expert at Imperial College London, who took part in the Vò project, told the Financial Times. “That is what makes the difference.”

The research allowed for the identification of at least six asymptomatic people who tested positive for Covid-19. ‘‘If these people had not been discovered,” said the researchers, they would probably have unknowingly infected other inhabitants.

“The percentage of infected people, even if asymptomatic, in the population is very high,” wrote Sergio Romagnani, professor of clinical immunology at the University of Florence, in a letter to the authorities. “The isolation of asymptomatics is essential to be able to control the spread of the virus and the severity of the disease.”

Facebook Twitter Pinterest Medical personnel testing for Covid-19 in Vò, Italy, on 23 February. Photograph: Nicola Fossella/EPA

There are many experts and mayors in Italy who push to carry out mass tests in the country, including asymptomatic ones.

“A test does no harm to anyone,” said the governor of the Veneto region Luca Zaia, who is taking action to test every single inhabitant of the region.” Zaia, described Vò as, ‘‘the healthiest place in Italy’’. ‘‘This is proof that the testing system works,’’ he added.

“Here there were the first two cases. We tested everyone, even if the ‘experts’ told us this was a mistake: 3,000 tests. We found 66 positives, who we isolated for 14 days, and after that 6 of them were still positive. And that is how we ended it.’’

However, according to some, the problems of mass tests are not only of an economic nature (each swab costs about 15 euros) but also at a organisational level.

On Tuesday, the WHO representative, Ranieri Guerra, said: “Director General Tedros Adhanom Ghebreyesus has urged the identification and diagnosis of suspected cases and symptomatic contacts of confirmed cases to be increased, as much as possible. At the moment, the recommendation to carry out mass screening has not been suggested.”

Massimo Galli, professor of infectious diseases at the University of Milan and director of infectious diseases at the Luigi Sacco hospital in Milan, warned carrying out mass tests on the asymptomatic population could however prove to be useless.

“The contagions are unfortunately constantly evolving,” Galli told the Guardian. “A man who tests negative today could contract the disease tomorrow.”