The theory is that banning mass public events where hundreds of attendees can infect themselves in the space of a few hours, along with other measures such as wearing face masks, might slow the pace of the new coronavirus’s progression to a manageable level even as shops and factories reopen.

Researchers believe that the explosive growth of coronavirus infections that overwhelmed hospitals in some countries was primarily driven by such events earlier this year—horse races in Britain, carnival festivities in the U.S. and Germany or a soccer match in Italy…

There is little doubt about the mechanisms involved in superspreading events. A study published by the National Academy of Sciences in the U.S. last week found that one minute of loud speech was enough to produce thousands of droplets that remain airborne for about 12 minutes, potentially able to infect anyone in the area. Similar studies have shown that virus-laden aerosols, particles smaller than droplets, can levitate for hours after being released in indoors spaces.

A more surprising finding is that mass infections tend to be more serious than those contracted in other circumstances, perhaps because of sustained exposure to a larger amount of virus.