New international study led by prof. Massimo Ciccozzi

December 17, 2020  - Sars-CoV-2 has spread in Italy through 13 different viral strains. And after the summer, the recovery of the Covid-19 pandemic was favored by the super-spreaders together with the local micro-outbreaks of which control was rapidly lost. These are some of the conclusions reached by the international team of 28 scientists led by teacher Massimo Ciccozzi, Head of the Medical Statistics and Epidemiology Unit of the Faculty of Medicine and Surgery ofUniversità Campus Bio-Medico di Roma with Davide cella from the Maryland Institute of Human Virology, USA e Marco Salemi of the University of Florida.

The study, a contribution on the MedRxiv portal open to comments from the scientific community, shows how the Italian pandemic from Covid-19 is characterized by a cluster diffusion in environments such as families, communities and healthcare residences and certifies that the increase in mobility during last summer allowed the virus to "break free" and get out of those closed areas in which it had remained contained until the end of spring, thanks to the restrictions observed in the lockdown.

A radical change in general behavior that has led to the loss of contact tracing and the new escalation of infections and deaths in recent months.

“Clusters - explains Professor Ciccozzi - they act as “hidden reservoirs” of the disease. Small groups of individuals initially infected by a so-called "super-spreader" and then able to infect themselves due to the reduction of limits and restrictions on the movement of people ".

Furthermore, according to the same study, the mutations in this virus that differentiate the 13 strains circulating in Italy, while having an impact on the level of contagiousness, do not change the pathogenicity of the virus nor therefore its ability to make us sick and kill. "Indeed – explains Ciccozzi again – the DG614 mutation that we identified last March and which made the virus more contagious was found in 98 percent of the Italian genomic sequences deposited in the database".

"In other words, if the ability of the different strains to transmit the disease varies, the mechanisms through which the virus manages to enter the human body and make us ill have not changed so far, based on the strain" concludes Ciccozzi. “From an evolutionary point of view, this means that the Spike protein on which mRNA vaccines are based does not currently seem to be involved in these mutations. So the vaccine efficacy ofchiarata remains unchanged”.

This element is particularly important in view of the launch of the national vaccination campaign.