BIHUB PATH

November 26, 2021

Medicine

What is the real risk of infection during a match?

By Carlos Lago Peñas.

Physical distance is one of the most important measures to prevent the SARS-CoV-2 infection.1,2 However, maintaining the recommended interpersonal distance is not possible in most sports, including football. Thus, the World Health Organization (WHO) considers team sports high-risk for COVID-19 due to the physical contact and proximity between the players.3 However, the scientific evidence supporting the probability of spreading the virus during a football game is limited. Can football be considered a high-risk sport?

Three articles have recently been published describing exposure to SARS-CoV-2 during a football game. Knudsen, Thomasen, and Andersen (2020)4 assessed the risk of being infected by SARS-CoV-2 throughout a match by combining two different variables: the time that two players are less than 1.5 metres apart and the probability of stepping on a region of the field where another player has been 2 seconds before. Positional data were collected using a semiautomatic tracking system (Tracab, ChyronHego). Analysis of 14 Danish National League matches from the 2018-19 season showed that the average exposure time of a player during a football match was less than one minute and a half (87.8 seconds). The highest value was 656.9 seconds, and the lowest was 0.

Gonçalves et al. (2020)5 studied the risk of interpersonal exposure caused by a football match using two measures of respiratory exposure. One was the accumulated time in which two players were within 2 metres from the other football players. The other measure was the aggregate time that everyone was exposed to the aerosols left by the movement of the other individuals (also considering the distance of 2 metres). To do this, they monitored all the players and referees during an international football match. Positional data were collected using a semiautomatic tracking system (Tracab, ChyronHego). According to their results, the players spent an average of 32 seconds exposed to interpersonal contact of less than 2 m with other footballers. The highest exposure value reached 395 seconds between two players from opposing teams.

Garrido et al. (2021)6 measured the time a player is less than two meters away from other players. The sample consisted of 60 matches from the Spanish league (30 from LaLiga Santander and 30 from LaLiga Smartbank). The position and distance between the players were also collected using the TRACAB tracking system used by Mediacoach. The results suggest that, although there is significant heterogeneity in the measurements, the player-player interactions within a radius of 2 m were, in all cases, less than 15 minutes throughout a match. We should also remark that the respiratory exposure time depends on the specific position. While the goalkeepers barely have an average contact time of 7 seconds, the forwards are the ones who may be at risk of contagion for the longest time. In any case, the most frequent probability is that footballers are less than 30 seconds during a match at less than 2 metres from other players.

A couple of additional essential facts. Interestingly, only about 35% of close contacts occur when the ball is in play. In addition, contact with rivals only accounts for 37% of total contact time; players are more in contact with their teammates. Interestingly, this behaviour is not fulfilled by goalkeepers who contact rivals around 68% of the time (See Table 1). Secondly, game situations that lead to spikes in proximity between players occur when the ball is out of play. The blue and red colours in Figure 1 indicate, respectively, whether the ball is in play in the match or not. The highest values correspond to fouls (minutes 11 and 26), corner kicks (minute 6), and goal celebrations (minute 35) (see Figure 1).

Table 1. Contact type: ball in play and rivals. First row: percentage of contact time with the ball in play. Second row: percentage of contact time with rivals.
Figure 1. Proximity between players in a match

In short, it seems that football can be considered a sport with a minimal risk for players getting infected by SARS-CoV-2. This assessment supports the limited time in which two players are less than 2 metres apart in a match as well as the match is practiced outdoors. In professional football, compliance with strict health protocols (PCR tests, bubbles of cohabitation, medical control, etc.) further reduces the risk of contagion. In amateur and training football, where it is impossible to implement the actions described above, masks are an excellent additional measure. In addition, considering the research results, it would be interesting to make some adaptations in the game’s rules that eliminate or reduce the situations in matches where the interpersonal distance between the players is reduced. Thus, some of the measures that could apply to reduce the risk of interpersonal exposure could be:7.8

  • Preventing collective goal celebrations.
  • Avoiding the “wall” in free kicks or reducing the number of players in the wall: only one player or more if there is a separation of at least 1.5 metres between them.
  • Replacing free kicks with accumulated points for a penalty, direct free kick, free kick, etc. (for example, every 5 fouls mean a defending free kick).
  • Replacing corners or throw-in/sideline throw-in in favour with accumulated points for a penalty, direct free kick, free kick, etc. For instance, every 2 corners or throw-ins mean a defending free-kick.
  • Entering temporary exclusions with each fault.
  • Spreading the total playing time over more periods in each game.
  • Reducing the continuous playing time of each athlete to a maximum of minutes.
  • Allowing more changes.
  • Playing with fewer football players to increase the number of metres/players.

References:

1 European Centre for Disease Prevention and Control. Considerations Relating to Social Distancing Measures in Response to COVID-19—Second Update. 23 March 2020; ECDC: Stockholm, Sweden, 2020.

2 World Health Organization. Overview of Public Health and Social Measures in the Context of COVID-19. Interim Guidance. 18 May 2020; World Health Organization: Geneva, Switzerland, 2020.

3 World Health Organization. Considerations for Sports Federations/Sports Event Organizers When Planning Mass Gatherings in the Context of COVID-19. Interim Guidance. 14 April 2020; World Health Organization: Geneva, Switzerland, 2020

4 Knudsen, N. S., Thomasen, M. M., and Andersen, T. B. (2020). Spread of Virus during Soccer Matches. Medrxiv. https://www.medrxiv.org/content/10.1101/2020.04.26.20080614v1.full.pdf+html (accessed 12th April 2021).

5 Gonçalves, B., Mendes, R., Folgado, H., Figueiredo, P., Travassos, B., Barros, H., Campos-Fernandes, A., Beckert, P. y Brito, J. (2020). Can Tracking Data Help in Assessing Interpersonal Contact Exposure in Team Sports during the COVID-19 Pandemic? Sensors, 20, 6163. https://doi.org/10.3390/s20216163

6 Garrido, D., Antequera, D.R., Campo, R.L.D, Resta, R. y Buldú JM (2021) Distance Between Players During a Soccer Match: The Influence of Player Position. Front. Psychol. 12:723414. doi: 10.3389/fpsyg.2021.723414.

7 Lago Peñas, C. (2021) Guias dxt galego 2. Volviendo con sentidiño. Recomendaciones para  la aceleración de la reactivación y readaptación técnico/táctica del deportista para su motivación y acercamiento progresivo a las exigencias del partido. Xunta de Galicia. https://deporte.xunta.gal/sites/w_deport/files/documentacion/paxina_estatica/xunta-deportes-protocolo-miolocastellano_parte4-v7_organized_0.pdf

8 Lago Peñas, C. (2021) Guias dxt galego 4. Volviendo con sentidiño. Acercarse del modo más seguro posible a la vuelta a la competición de niños, jóvenes y amateurs. Xunta de Galicia. acercarse del modo más seguro posible a la vuelta a la competición de niños, jóvenes y amateurs

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