As sports fans from across the globe get ready for the 2024 Paris Olympics , health officials and experts are urging vigilance while warning about potential disease risks for those attending the Summer Games in person. The Olympics officially get under way on Friday, with more 10,000 athletes taking part and an estimated 15 million spectators expected to attend, including two million visitors. The World Health Organization published new guidance last week for spectators travelling for the Olympic and Paralympic Games.

The latter will start next month. The guide, developed jointly by WHO Europe, the French Ministry of Health and Prevention, Santé Publique France and the European Centre for Disease Prevention and Control informs travellers about vaccinations, respiratory infections, heat risks and alcohol consumption, among other advice. “The thing about an Olympics or any kind of large event is you’ve got maximum population mixing,” said Colin Furness, associate professor at University of Toronto’s faculty of information.

Story continues below advertisement “You’ve got people coming from all over the globe and converging. That’s a lot more dangerous than a bunch of locals getting together at the local stadium where you all come from the same population,” he told Global News in an interview on Monday. Furness said that the overriding risk to fans comes from crowds, especially indoors, and those can start as early as at the airport when lining up to check in, s.