The Economist (2022-01-08)

TheEconomistJanuary8th 2022

Graphic detail Covid-19 and football

77

Stoppage time

“A

fter five minutes ofmovement  I

had  to  stop  because  I  was  struggling

to  breathe,”  explained  Paulo  Dybala  in

March  2020.  It  was  a  common  experience

of  covid­19  relayed  by  a  very  uncommon

man. Mr Dybala is a star forward for Juven­

tus, a leading Italian football team, whose

athleticism fetches more than $10m a year.

Fortunately  for  Mr  Dybala,  the  post­

ponement  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.  Be­

nedikt Schmal of Heinrich Heine Universi­

ty as well as J. James Reade of the Universi­

ty  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  some­

times  anonymised).  They  then  combined

this register with detailed data from Opta, a

sports­data  firm,  on  performance  mea­

sures  like  minutes  played,  distance  run

and passes completed.

If relative performance between infect­

ed  and  uninfected  players  was  stable  be­

fore  contracting  covid,  but  declines  after,

this should indicate the lingering effects of

the virus. Using this statistical methodolo­

gy (called “difference­in­differences”), the

authors  detected  a  decline  of  9%  in  min­

utes  played.  Passes  completed  fell  by  6%

and did not return to normal for months.

The Economistfound  a  similar  pattern

when  we  replicated  the  analysis  using  a

more  sophisticated  player­value  score  (a

composite of more than 40 on­field activi­

ties) provided by the Twenty First Group, a

sports­intelligence 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, fit and able to get world­class med­

ical 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  eveninthe

professional game is a worrying sign.n

Even for elite athletes, the effects

of the virus linger

Germany Italy

2020 2021 2020 2021

0

1,000

1,500

500

2,000

2,500

Footballersintopleague*

Generalpopulation

75-0 0-75 75-150 150-225 Over 225

Daysbefore/afterinfection

Over 225 225-150 150-75

Over 225 225-150 150-75 75-0 0-75 75-150 150-225 Over 225

75-0 0-75 75-150 150-225 Over 225

Daysbefore/afterinfection

Over 225 225-150 150-75

5

0

-5

-10

-15

-20

2

0

-2

-4

-6

0 22

2

0

-2

-4

-6

95%confidence

interval

→ Owing to strict testing, covid-1 was detected among players at high rates

Confirmed covid-19 cases per 100,000 people, to July 2021

→ Covid-1 affected players’ time on pitch and pass performance months later

Relative to players who didn’t test positive for covid-19

Likelihood of playing, percentage-point change

Number of minutes played per game

Numberofpassescompletedper9minutes

Source:“Thelongshadowofaninfection:Covid-19andperformanceatwork”,

byKaiFischer,J. JamesReadeandW.BenediktSchmal,workingpaper,221 *Seven-daymovingaverage

Five months after infection, players

still make four fewer passes. A typical

top footballer makes 4 per game