More than 40 % of people living in an Italian city, tested positive COVID-19, had no sign of disease, according to a study published Tuesday, highlighting the potential for spread of the new coronavirus.
This research shows the importance of the tests of mass and isolation of the carriers of the virus to contain the foci of contamination (” clusters “), according to the authors, whose work was published in the scientific journal Nature.
At the end of February, the first death of Italy has been registered in the town of Vo (3200 inhabitants), near Padua (Veneto region, north of the country). The city was immediately put on a two-week confinement, during which the researchers were able to test virological with more than 85 % of the population.
In the beginning of the quarantine, a total of 2.3 % of the population of Vo ” were infected, compared with 1.2% at the end of the containment and 42.5% of people who tested positive had no symptoms at the time of the test, nor after.
According to the authors, their study shows that the rapid isolation of the case and the test mass were used to eliminate efficiently the viruses of this small town.
“The screening of all citizens, whether they have or do not have symptoms, you can manage the spread of the disease and to prevent epidemics to become uncontrollable,” according to Andrea Crisanti, from the department of molecular medicine, University of Padua and of the department of life Sciences at Imperial College London. “Despite a transmission of “silent” and widespread, the disease can be controlled. ”
Asymptomatic carriers of the infection had a viral load similar to those that have fallen ill, suggesting that, even without being themselves sick, they can spread the virus.
“Even asymptomatic infections have the potential to contribute to transmission,” insists Enrico Lavezzo, University of Padua, co-author of the study.
Unaware of their infection, asymptomatic individuals may, in fact, according to their mode of life and their craft, meet a large number of people, without changing their behavior (including gestures barriers : mask, physical distance, hand hygiene).
In addition, none of the children under 10 years of age was positive in the test, even if they lived with adults who become infected, according to the study.
“The study Vo” demonstrates that the early identification outbreaks of infection and rapid isolation of cases of infection with or without symptoms, can eliminate the transmission and put a stop to this epidemic in its infancy, ” says a researcher, co-author of the study, Ilaria Dorigatti, MRC Center for Global Infectious Disease Analysis from Imperial College London.