The coronavirus is now sweeping across the United States. But before the outbreak grew here, Italy was the epicenter for the respiratory disease in Europe. According to the Associated Press, a Champions League match between Atalanta and Valencia in February may have been the reason why the virus spread so rapidly in the country. Atalanta hosted the Spanish team on Feb. 19 in Milan.

The match is being called "Game Zero" because it was played just two days before the first positive case of COVID-19 was confirmed in Italy. The head of pulmonology at a Bergamo hospital, which is outside of Milan and the usual home of Atalanta, recently described the Champions League match as "a biological bomb." There were also about 2,500 Valencia fans in the stands for the match, and 35 percent of Valencia's team tested positive for the coronavirus a few weeks later.

Bergamo Mayor Giorgio Gori echoed that statement.

"We were mid-February so we didn't have the circumstances of what was happening," Gori said this week during a live Facebook chat with the Foreign Press Association. "If it's true what they're saying that the virus was already circulating in Europe in January, then it's very probable that 40,000 Bergamaschi in the stands of San Siro, all together, exchanged the virus between them. As is possible that so many Bergamaschi that night got together in houses, bars to watch the match and did the same.

"Unfortunately, we couldn't have known. No one knew the virus was already here," Gori added. "It was inevitable."

A journalist that covered the match became the second person to test positive for the coronavirus in Bergamo. In addition, several Valencia fans that attended the match became infected.

As of Tuesday, there were nearly 7,000 people in Bergamo that have tested positive for the coronavirus. More than 1,000 people have died as a result of the virus, which makes Bergamo the most heavily hit province during the COVID-19 outbreak.

Valencia also had 2,600 cases of the virus.

As of Thursday afternoon, there have been at least 490,000 confirmed coronavirus cases worldwide, according to CBS News, and more than 22,000 people have died due to the virus. In addition, multiple states are under a state of emergency and public health officials are recommending large gatherings of people -- including sporting events -- be canceled or closed to the public.