People attend a test music festival as part of a national research programme assessing the risk of COVID-19 transmission in Liverpool, Britain May 2, 2021. Live music returned to the birthplace of The Beatles after a long coronavirus-enforced silence on Sunday when the English city of Liverpool hosted a one-off music festival to test whether such events spread the virus. REUTERS/Jason Cairnduff

British band Blossoms performs during a test music festival as part of a national research programme assessing the risk of COVID-19 transmission in Liverpool, Britain May 2, 2021. Around 5,000 people ditched face coverings and social distancing rules in the name of science and music. REUTERS/Jason Cairnduff

People attend a test music festival as part of a national research programme assessing the risk of COVID-19 transmission in Liverpool, Britain May 2, 2021. They attended the outdoor event having tested negative for COVID-19, and promised to get themselves tested again five days after the festival. REUTERS/Jason Cairnduff

A woman enjoys her time during a test music festival as part of a national research programme assessing the risk of COVID-19 transmission in Liverpool, Britain May 2, 2021. Their data will be used by the government's Events Research Programme to help understand the effect of crowds on the spread of the virus. REUTERS/Jason Cairnduff

British band Blossoms performs during a test music festival as part of a national research programme assessing the risk of COVID-19 transmission in Liverpool, Britain May 2, 2021. REUTERS/Jason Cairnduff

People attend a test music festival as part of a national research programme assessing the risk of COVID-19 transmission in Liverpool, Britain May 2, 2021. REUTERS/Jason Cairnduff