Later that evening, Liverpool hosted Atletico Madrid in a Champions League football match at Anfield.
Around 3,000 visiting fans were allowed to travel to Merseyside and mingle in bars and restaurants, despite the fact Madrid was the epicentre of the outbreak in Spain, and at that point accounted for almost half of the country's confirmed cases.
Liverpool supporter Joel Rookwood, who has been ill for eight weeks, believes he contracted Covid-19 that evening, and recalled how when goals were scored, spectators were oblivious to the risk of transmitting the virus.
"The celebrations were some of the most physical that I've experienced," he said. "People were jumping all over each other."
The Spirit Of Shankly, a Liverpool supporters group, said it raised concerns about the arrival of fans from Madrid at a council-chaired safety meeting two days before the match but were told it would go ahead in accordance with government advice.
But Liverpool FC would not have been able to unilaterally call off the match - to decide which of the two clubs progressed to the Champions League quarter-finals. That decision would have had to come from one of football's governing bodies, such as the competition's organiser Uefa.
Prof Spector said: "I think sporting events should have been shut down at least a week earlier because they'll have caused increased suffering and death that wouldn't otherwise have occurred."
In a statement, the government said: "There are many factors that could influence the number of cases in a particular area, including population density, age, general health, and the position of an area on the pandemic curve."
