England's progress to the Euro 2020 final caused a "significant risk to public health across the UK", according to scientists from Public Health England (PHE).
Data from NHS Test and Trace showed that more than 9,000 COVID cases were linked to Euro 2020 matches.
Wembley hosted eight games during the month-long tournament and figures indicated there were a total of 3,036 likely infectious cases at the time of those games, with a further combined 6,376 people likely getting infected around the time they took place.
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A report on the public health impact of mass events also found that "particularly high numbers were identified" at the Euro 2020 final on 11 July, a match which England lost on penalties to Italy.
Data showed 2,295 people in or around Wembley were likely to have been infectious at the time of the match, with a further 3,404 people in and around the ground potentially being infected around the time of the final.
The match, with a crowd of around 67,000 inside the stadium, was England's first final in an international soccer tournament since the country hosted and won the 1966 World Cup.
The report's authors concluded that Euro 2020 and England's progress to the final "generated a significant risk to public health across the UK even when England played overseas".
"This risk arose not just from individuals attending the event itself, but included activities undertaken during travel and associated social activities," they added.
"For the final and semi-final games at Wembley, risk mitigation measures in place were less effective in controlling Covid transmission than was the case for other mass spectator sports events."
Dr Jenifer Smith, deputy medical director of Public Health England, said: "Euro 2020 was a unique occasion and it is unlikely we would see a similar impact on COVID-19 cases from future events.
"However, the data does show how easily the virus can spread when there is close contact and this should be a warning to us all as we try and return to a cautious normality once again."
The NHS Test and Trace data also showed 585 cases were recorded at the time of the Formula 1's British Grand Prix, which hosted the largest crowd in the UK in over 18 months, with more than 350,000 people attending the event over three days.
Other trial events over a four-month period showed far fewer positive tests and were either broadly in line with or lower than national averages.
The British Grand Prix at Silverstone in July drew a 350,000-strong crowd, the largest in Britain in more than 18 months, over three days and had 585 cases recorded by NHS Test and Trace.
Of those cases, 343 were likely to have already been infectious around the time of the event and the rest likely to have acquired an infection then.
The Wimbledon tennis championships, with around 300,000 people attending over the two weeks, recorded 881 cases.
"We've shown that we can reintroduce mass sports and cultural events safely but it is important that people remain cautious when mixing in very crowded settings," said Culture Minister Oliver Dowden.
"So that we can keep the football season, theatres and gigs safe with full crowds this winter, I urge sport, music and culture fans to get the vaccine as this is the safest way we can get big events firing on all cylinders once more."