Only 28 cases of COVID-19 were recorded after nine large-scale events studied to assess the impact on the transmission of the virus, a government report says.
A total of just over 58,000 people went to the indoor and outdoor events but there were “no major outbreaks”.
At the time, levels of cases of COVID-19were low and testing before and after events was also low, making conclusions difficult.
Pilot events included the FA Cup final, the Brit awards and two Circus nightclub dance nights in Liverpool.
The Events Research Programme was commissioned by the prime minister in February to test how mass gatherings could be held safely, and what measures would help reduce the risk of the virus spreading.
Scientists involved in the research said large indoor events could post “a higher potential risk of transmission” because of people being close to each other and poor ventilation.
But they said “pinch points”, where people were crowded together for a time, existed at both indoor and outdoor events.
They added that face coverings, restrictions on food and drink, testing, ventilation and social distancing could all be used to reduce the risk of transmission.
The report said no decisions had been taken on fully reopening mass events.
The government is due to set out its plans for this before 19 July – the current date for the final easing of lockdown restrictions in England.
All attendees were required to provide a negative lateral flow (rapid) test before they could enter the events.
They were also asked to take a voluntary PCR test (which is sent to a lab) before and after the event.
“Low uptake of PCR testing before and after events meant evidence of direct transmission at events was challenging to determine,” the report says.
Some 26-31% of attendees returned a PCR test after an event, but researchers said they also tested their close contacts and those of people who tested positive to find out more about potential spread.
Data on cases in the local populations who made up the audience at the events, such as Liverpool, were also studied.
But the report says the figure of 28 positive cases of COVID-19 at events – 11 identified as potentially infectious and 17 as potentially infected at or around the time of an event – should be “interpreted with extreme caution”.
This is because of “relatively low levels of community prevalence of Covid-19 at the time of running the first phase of pilots” – and the spread of the now-dominant Delta variant could increase those figures, the report noted.