“AFTER FIVE minutes of movement I had to stop because I was struggling to breathe,” explained Paulo Dybala in March 2020. It was a common experience of covid-19 relayed by a very uncommon man. Mr Dybala is a star forward for Juventus, a leading Italian football team, whose athleticism fetches more than $10m a year.
Fortunately for Mr Dybala, the postponement of football matches until June 2020 left him enough time to recover. But for other players at the highest echelons of the sport, even three months may not have been long enough.
That is according to recent research by three economists—Kai Fischer and W. Benedikt Schmal of Heinrich Heine University as well as J. James Reade of the University of Reading. With some detective work, they were able to identify 90% of the 257 positive cases reported by the German Bundesliga and Italian Serie A through to July 2021 (the announcements are sometimes anonymised). They then combined this register with detailed data from Opta, a sports-data firm, on performance measures like minutes played, distance run and passes completed.
If relative performance between infected and uninfected players was stable before contracting covid, but declines after, this should indicate the lingering effects of the virus. Using this statistical methodology (called “difference-in-differences”), the authors detected a decline of 9% in minutes played. Passes completed fell by 6% and did not return to normal for months.
The Economist found a similar pattern when we replicated the analysis using a more sophisticated player-value score (a composite of more than 40 on-field activities) provided by the Twenty First Group, a sports-intelligence consultancy. In the ten weeks after infection there was an average drop in score of 0.14 standard deviations (equivalent to the median player dropping to the 30th percentile). But after ten weeks these reverted to normal, suggesting that players may compensate for passing less and spending less time on the pitch.
The odds of recovery from covid are stacked in favour of footballers, who are young, fit and able to get world-class medical care. The incentives to recover fully are much greater than for the ordinary citizen. Research on long covid is still progressing. But the fact that it may linger even in the professional game is a worrying sign. ■
Source: “The long shadow of an infection: Covid-19 and performance at work”, by Kai Fischer, J. James Reade and W. Benedikt Schmal, working paper, 2021
This article appeared in the Graphic detail section of the print edition under the headline “Stoppage time”