The world’s largest phone show, Mobile World Congress, is moving forward with an in-person event in June, despite the risks that it could turn into a COVID-19 superspreader event.

Over 100,000 people usually attend MWC. John Hoffman, the CEO of the GSM Association (which organizes the show) says those numbers will be scaled back this year. He told Mobile World Live that he’s expecting around 50,000 people will travel to Barcelona, interact with each other and locals, and then fly back home.

The event’s safety and security page says organizers will be “controlling crowd density” and requiring masks. Hoffman said he wouldn’t expect everyone in attendance to be vaccinated against COVID-19. “Our view is it would be great if the world was vaccinated, but we can’t rely on that in 2021,” he told Mobile World Live.

Instead, the group is asking that everyone in attendance have a negative COVID-19 test within 72 hours of their arrival. Testing is not a sufficient way to prevent the spread of the coronavirus, particularly when tests are done that far in advance. Someone could very easily test negative, contract the virus en route to MWC, and spread the disease when they arrive. XPrize founder Peter Diamandis relied on testing to hold an in-person conference in California with under 100 people in January — but there was no quarantine requirement, and mask-wearing wasn’t enforced. Dozens of people tested positive for the virus afterward.

Big meetings and events, especially when they’re connected with international travel, can be breeding grounds for coronavirus infections. Hundreds of thousands of COVID-19 cases were tied back to a biotech conference in Boston at the start of the pandemic, for example. Holding a large event places not only the attendees at risk, but also the people who live in the region where the event takes place.

The GSM Association fought against canceling its 2020 show, which was set to take place last February just as COVID-19 was emerging as a worldwide problem. It took major brands like LG, ZTE, Sony, and Amazon pulling out for the group to shut down the event.

COVID-19 is still a major threat worldwide. Spain is currently averaging around 12,000 new cases and 400 deaths per day. While the situation may improve by June, people around the world will still be vulnerable to the disease. The vaccine rollout in Spain is slow, with only around 65,000 doses given per day. Most of the population will still be unvaccinated come summer if that pace continues.