Measles: Nearly one in ten Italians at risk of infection

Nearly 10% of Italians are at risk of measles, with young adults between the ages of 20 and 40 most susceptible to infection in many regions, even those with high childhood vaccination coverage. This is according to a study coordinated by the ISS (Istituto Superiore di Sanità) and the Bruno Kessler Foundation and published in the journal The Lancet Infectious Diseases .

The study

The study analyzed nearly 15,000 measles cases (with 14 deaths) reported to the national integrated measles and rubella surveillance system between 2013 and 2022. The highest incidence of measles was among children under 5, while over half of the cases involved young adults between 20 and 39. Among cases with known vaccination status, nearly nine out of ten were unvaccinated. A portion of the cases were analyzed in more detail to understand the transmission modes of the outbreaks that occurred during this period. The researchers also estimated the number of people susceptible to measles in 2025 across all regions. The majority (88.9%) of secondary infections, i.e., those that follow the so-called "index case" in outbreaks, were caused by unvaccinated individuals. Only 1.1% of infections occurred among people who had both received at least one dose of the vaccine. A third (33.3%) of transmission episodes occurred among young adults, who also accounted for a significant proportion of transmission to children under 5 years of age. 35.5% of secondary infections occurred within families.

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Difference between regions in immunity

By 2025, 9.2% of the Italian population is susceptible to measles, and only 88.2% of young people under 20 are immune. This figure varies widely across regions: among the general population, the central and northern regions have the highest percentages of susceptible people, while among young people under 20, the province of Bolzano and Calabria appear to have the highest susceptibility rates.

Unvaccinated adults contribute to virus transmission

Some regions have achieved high rates of childhood vaccination, thanks to the mandatory vaccination law introduced in 2017, but this does not necessarily translate into a lower risk of transmission, especially given the presence of large pockets of unimmunized adults. The estimated reproduction number for 2025 ranges from 1.31 to 1.78 across all regions, consistent with the previous decade. "Unvaccinated adults contribute substantially to measles transmission in Italy," the study authors write. "There is great regional heterogeneity in immunity: some regions show low vaccination coverage among children, while others have a large proportion of susceptible adults. These findings emphasize the need for targeted vaccination strategies, including catch-up campaigns aimed at adults."

The European measles elimination programme has not yet achieved its goal

Gianni Rezza , former director of Prevention at the Ministry of Health and now associate professor of Hygiene at the Vita-Salute San Raffaele University in Milan, confirms the importance of the study: "It is necessary to maintain high vaccination coverage among children, but also to promote vaccination among young adults who are still susceptible to infection, who most likely support the circulation of the measles virus. Anyone who wants can get vaccinated completely free of charge because a measles elimination program is underway in the European region, which, however, has not yet achieved its primary objective."

Lopalco: "It's a serious disease, but it can be eradicated like smallpox."

"Measles remains a serious disease, with potentially fatal complications. Those most affected are unimmunized young adults and infants still too young to be vaccinated. But it can be eradicated, as was done with smallpox. However, additional effort is required, as the virus is even more contagious than smallpox. It is important to vaccinate those who are still susceptible, regardless of age," says epidemiologist Pier Luigi Lopalco , professor of Hygiene at the University of Salento. He adds: "We need to close these immunity gaps to prevent the virus from circulating and finally eliminate it."