It could be seen as another tragic day for the Liverpool club, who went through the Heysel and Hillsborough disasters in the 1980s.
Edge Health, a group which uses data-modelling to analyse NHS data, say the deaths would have occurred 25 to 35 days after the match.
The Mayor of Madrid Jose Luis Martinez-Almedia has already stated it was a "mistake" to play the match.
"It didn't make any sense that 3000 Atletico fans could travel to Anfield at that time," he told a Spanish radio station.
"It was a mistake. Looking back with hindsight, of course, but I think even at that time there should have been more caution."
There were an estimated 640,000 positive cases in Spain at the time, and 100,000 in Britain. Many businesses, schools and restaurants were already closed in Spain, with some matches having also been moved behind closed doors.
Around the same time, horse racing's four-day Cheltenham Festival which had a 250,000 crowd was also allowed to go ahead, with Edge Health believing that led to 37 more coronavirus-linked deaths.
The UK Government introduced social distancing a few days later.
In April, the Mayor of Liverpool City Region told the BBC that an investigation was required.
"If people have contracted coronavirus as a direct result of a sporting event that we believe shouldn't have taken place, well that is scandalous," Steve Rotheram said.
"That needs to be investigated to find out whether some of those infections are due directly to the Atletico fans. There were coronavirus hot cities, and Madrid was one of those."
Atletico won in extra time for a 4-2 aggregate victory which put them in the quarter-finals.
Everton manager Carlo Ancelotti claimed weeks later that his Liverpool counterpart Jurgen Klopp stated the playing of the match amounted to a "criminal act".
Klopp and Atletico manager Diego Simeone touched arms before the game. Simeone initially went to shake hands even though this was banned.
And as Liverpool fans around the tunnel extended hands towards the players heading out for their warm ups, Klopp said: "Put your hands away you f****** idiots"