Pathogens have an easy time of it at international soccer tournaments. This is because many people watch the games together, whether in a private living room, in a pub or at a public screening, where coronavirus, for example, can easily spread. For instance, it can be clearly demonstrated that increased contact among fans during Euro 2020 resulted in numerous infections. However, the strength of the effect varies greatly from country to country. The team from Göttingen, Bonn and Munich investigated for twelve of the participating countries how infection dynamics developed during and after Euro 2020 in the summer of 2021.
To do this, the researchers used case numbers broken down by gender to distinguish the contribution of the Euro 2020 championship to infection dynamics from other factors, because more men than women follow soccer games: Consequently, there should also be more infections among men than among women directly after games. This gender ratio is reflected in different infection rates in several participating countries. The team used this to calculate how many infections were due to people watching the games together.
The difference in the impact of pandemic preconditions is well illustrated by the example of the Czech Republic and England: For example, the Czech Republic played five games in the most recent European football championship. However, despite great enthusiasm for soccer in the country, there were only about 460 additional infections per million inhabitants. Euro 2020 had a much greater impact in England. There, around 11,000 people per million population consequently became infected with the coronavirus - that is more than ten times as much!
This was not only due to the greater number of matches, as the English team played seven games before the final, but rather to the completely different starting situation: In the Czech Republic, there were comparatively few infections at the time of the Euro 2020 championship, whereas in England the number of cases was already high at the start of the tournament. The reproduction number, which indicates how many people an infected person infects, was also relatively high. "In this situation, with high case numbers and high reproductive numbers, the major sporting event gave a powerful boost to the infection dynamics," says Viola Priesemann of the Max Planck Institute for Dynamics and Self-Organization in Göttingen.
Around 840,000 additional infections due to the Euro 2020 championship
Infections apparently occurred less in stadiums than at private gatherings, such as pubs and homes, where people watched the games together. The researchers conclude this because no significant effect could be measured for either the town or the country where the game was held, but it could be measured for the countries participating in the games. And, of course, the infections did not stop at the match days - because each infected person set off a chain of infections that, according to the model calculations, infected an additional four people per virus carrier on average during the study period until the end of July 2021. "You can see from this that infections are not a private matter," says Viola Priesemann. "Because through such chains of infection, the virus also spreads to vulnerable populations."
The model calculations analyze the jump in the number of cases among men relative to women and take into account country-specific parameterizations of the reporting delay in order to be able to assign these jumps to individual games. This resulted in approximately 840,000 additional infections caused by Euro 2020 for all twelve countries studied together. "If vulnerable groups are to be protected, then preventive measures are essential at a major sporting event," concludes Dr. Philip Bechtle of the Institute of Physics at the University of Bonn.
The comparison of countries clearly shows that, above all, a low incidence and a low reproduction number R are the best basis for minimizing superspreading occurrences due to large events to a manageable level. "Masks, increased testing and vaccination, and anticipatory contact reduction additionally help contain the spread of infection," says Bechtle, who is also a member of the University of Bonn's Transdisciplinary Research Area "Matter". This could reduce the burden of large-scale events on the heavily strained health care system in the event of future pandemics.
