Some of the 12,000 people who flew to Miami last weekend to attend the largest Bitcoin event in history have since tested positive for Covid-19.

It is unclear how many participants were infected.

The Bitcoin 2021 event drew cryptocurrency enthusiasts from around the world to the Mana Wynwood Convention Center in the arts and entertainment district of Miami. People crowded into lecture halls and networked during the three-day event. It was the first major conference since the coronavirus pandemic began, and many of the attendees said they were relieved to be among colleagues exchanging messages and updates.

There was no mask requirement and no vaccination certificate was required. Covid-19 was just a topic of conversation in connection with everyone’s excitement about being on the other side of the pandemic.

That is, of course, until some participants went to Twitter to say they tested positive for the coronavirus.

The #Bitcoin 2021 conference in Miami was the first major in-person conference since the pandemic began.

It could have been a “very common event” with dozens of attendees saying they tested positive for COVID-19.

– Mr. Whale (@CryptoWhale) June 10, 2021

For full disclosure, I attended the show after receiving two doses of the Moderna vaccine this spring. Vaccination isn’t a 100 percent guarantee of immunity, but I’m not showing any symptoms at the moment. A lot of my conversations with Uber and Lyft drivers started with a discussion about vaccination together.

It remains to be seen whether the conference will ultimately be billed as a superspreader event.

Everyone I’ve hung out with in Miami got Covid. Fortunately for me, I was hanging about a foot above everyone

– Larry Cermak (@lawmaster) June 10, 2021

It is unclear whether the city of Miami had a contingency plan for such an outcome. The mayor’s office and conference organizers did not immediately respond to CNBC’s request for comment.

On Tuesday, Florida said it would stop reporting daily Covid-19 cases and deaths as vaccinations increase and shift into the “next phase” of the pandemic. Florida reported an average of eight new cases per 100,000 residents last week, well below its pandemic high of 84 per 100,000, according to Johns Hopkins University.