Design of a method to prevent the spread of infectious diseases in airports CSIC researchers lead the development of a mathematical model that identifies the areas with the highest risk of contagion in means of transport. Implementing disinfection measures in crowded areas of airports, such as bars or restaurants, could reduce the risk of spreading viruses such as SARS-CoV-2.  In 2022, more than 61 million people transited through Europe's busiest airport, London Heathrow. That means that, every day, more than 160,000 people from different parts of the world shared the same space. To prevent the first undetected cases of viruses such as SARS-CoV-2 or H1N1 influenza from becoming an epidemiological problem, a study led by the Institute for Cross-Disciplinary Physics and Complex Systems (IFISC, CSIC-UIB) proposes a mathematical model that identifies the areas with the highest risk of contagion in means of transport and provides recommendations to prevent its spread. The results are published in the journal Nature Communications. When a person coughs, speaks, and even breathes, emits small respiratory droplets into the surrounding air. These airborne particles, known as aerosols, can carry viral particles from an infected person. Thus, the relationship between the number of people and the space available is critical when it comes to curbing the spread of contagious diseases. "Close social interactions are critical in the transmission of infectious pathologies, so crowds and crowds are a serious risk for triggering super-propagation events. There are occasions when maintaining interpersonal distance can be a challenge, such as, for example, in transportation hubs," highlights José Javier Ramasco, IFISC researcher who participated in the study. As the researcher points out, "these places are designed to optimize logistical efficiency, not to reduce crowding," so identifying the busiest areas can be key to mitigating the risk of spreading new infectious diseases. According to the study, this objective is achieved through a mathematical model capable of detecting those spaces within the airport most likely to transmit diseases. The researchers applied the new system to study how viruses such as H1N1 flu, SARS-CoV-1 and SARS-CoV-2, which caused the covid-19 pandemic, spread. By analyzing the itineraries of more than 200,000 anonymous individuals, collected at London's Heathrow airport between February and August 2017, they determined the areas with the highest risk of contagion: bars and restaurants. This is caused by connecting many people, in the same place and for long periods of time. "The dangerousness of the areas for contagion arises as a balance between the number of people passing by and the time they stay together. Those places are not always the most crowded, but it takes time in contacts to transmit the disease," Ramasco explains.  Once the hot spots of contagion have been identified, it is possible to develop a spatial immunization policy to prevent or reduce the risk of the pathogen spreading beyond the first undetected cases. This would be achieved through the use of ultraviolet rays, surface disinfection or air filtering. In addition, the researchers point out that the method can be applied to control any other uncharacterized pathogen (emerging diseases) and is generalizable to other modes of transport. "It can be used in train stations, subway stations, bus stations or other crowded places where it is not possible to maintain interpersonal distances, such as shopping malls or convention centers," he remarks. The project is the result of an international multidisciplinary collaboration developed within the Plataformas Temáticas Interdisciplinares del CSIC Salud Global i Mobility 2030. Along with IFISC, a joint center of CSIC and the University of the Balearic Islands, the French National Institute of Health and Medical Research (Inserm), the Bruno Kessler Foundation in Italy, and the company Cuebiq Inc, which collects users' locations and integrates them anonymously, have also participated in the project. "Implementing spatial immunization measures in the highest risk areas would help to contain and/or delay the spread of infectious agents in airports around the world, and would be particularly useful in the early stages of a pandemic, when drugs have not yet been developed," the researchers conclude.   Mattia Mazzoli et al. Spatial immunization to abate disease spreading in transportation hubs. Nature Communications. DOI: https://doi.org/10.1038/s41467-023-36985-0 CSIC http://ifisc.uib-csic.es/en/news/design-method-prevent-spread-infectious-di…