Italian study on measles: "Where vaccinations decline, the virus is more diverse and resilient."

Where measles vaccination coverage declines, the virus "not only spreads, but becomes more diverse, more resilient, and potentially more difficult to stop." These are the conclusions of a new study conducted by the Gabie group (together with Daria Sanna and Maria Perra of the University of Sassari, Enrico Bucci of Temple University, and Nicola Petrosillo of the Campus Bio-Medico University) submitted to the journal Genes. The study compares recent measles outbreaks in Italy in 2024 and Texas in 2025. The Gabie group is the new hub for monitoring epidemics created by Massimo Ciccozzi , Professor of Medical Statistics, and Francesco Branda , Researcher in the Medical Statistics Research Unit, both at the Campus Bio-Medico University of Rome. They also collaborate with Fabio Scarpa , Associate Professor of Genetics at the University of Sassari.

Despite having hit two high-income areas with advanced healthcare systems, the two epidemics followed very different trajectories, highlighting how important the timeliness and quality of data are in the public health response. " The difference is not just in the numbers, but in the depth of the data: in Texas we were able to work on data and updated almost in real time, disaggregated by age, vaccination status, and geographic distribution . This allowed us to precisely model the phases of the epidemic and identify critical intervention points,” explains Francesco Branda.

In Texas , the use of advanced statistical models (such as Arima and logistic regression) allowed us to identify three distinct phases of the epidemic: initial exponential growth, linear stabilization, and plateau. The models—the study states—showed excellent predictive capacity and confirmed a clear link between vaccination status and case incidence. In contrast, in Italy, the analysis was based primarily on monthly bulletins published by the National Institute of Health, making it difficult to detect early warning signals . Despite this, the analysis highlighted a key finding: the vast majority of cases occurred among people who were unvaccinated or had an incomplete vaccination cycle. However, in both settings, vaccination status was not statistically associated with the risk of hospitalization, suggesting that once the virus is contracted, other factors—such as age or comorbidities—have a greater impact on clinical severity.

The lesson is clear: integrate genomic sequencing into health surveillance.

"Measles is among the most contagious viruses in the world. Even a small gap in vaccination coverage can lead to an explosion of cases," Ciccozzi emphasizes. "The difference in hospitalization rates between the two outbreaks is not only clinical, but also social: the availability of data in the United States has allowed targeted interventions in at-risk communities. In Italy, however, we are late in responding."

In addition to traditional epidemiological analysis, the study conducted—through an integrated approach—an in-depth genomic analysis incorporating all available data from databases. "The result? Genetics tells us that, where vaccination coverage declines, the virus not only spreads, but becomes more diverse, more resilient, and potentially more difficult to stop," explains Scarpa. "The lesson is clear: integrating genomic sequencing into health surveillance is not only useful, but essential to prevent the return of diseases we thought were defeated."

"We hope this study will serve as a stimulus to strengthen surveillance infrastructures in Italy as well."

The study's results were made possible thanks to the continuous, interdisciplinary work of the Gabie group, which has distinguished itself in recent years for its ability to respond rapidly to numerous epidemic outbreaks, combining expertise in epidemiology, biostatistics, bioinformatics, and genetics. For each health emergency—from COVID-19 to H5N1 avian flu, from monkeypox (MPOX) to regional outbreaks of emerging viruses—Gabie activates an integrated system for collecting, harmonizing, and analyzing clinical, epidemiological, and molecular data. This integrated approach allows Gabie to offer a scientifically sound and timely response in complex and constantly evolving contexts, supporting more effective, personalized, and locally evidence-based containment strategies. It is no coincidence that the group is an integral part of the Global Outbreak Alert and Response Network (GOARN) and actively contributes to delineating the evolutionary trajectories of high-impact pandemic viruses.

"Without granular and interoperable data, prevention is impossible: cases just keep coming back," Branda concludes. "We hope this study will serve as a stimulus to strengthen surveillance infrastructure in Italy, too, with concrete investment in the digitalization of public health systems."