One dance fitness workshop led to 112 coronavirus cases in South Korea, a report says

• A new report has linked an outbreak of coronavirus in South Korea to a dance fitness workshop.
• Fitness instructors had attended a workshop in February where at least 8 participants were infected but didn't show symptoms.
• By March, those instructors were linked to at least 112 cases of coronavirus in dance fitness classes at 12 different fitness facilities in the region.
• Experts say that group fitness classes with a large number of people exercising intensely in a small space could increase risk of infection.
• Small yoga and pilates classes, however, were not linked to infections, possibly because the slower movement and fewer people decreased the risks.
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In early February, a group of dance fitness instructors in South Korea met for a workshop — 4 hours of intense aerobics with 27 people sweating together in a small space. Unbeknownst to them, 8 of those participants had coronavirus, but they were not yet showing symptoms.

Less than a month later, the virus had infected 112 people across 12 different fitness facilities in the region, all linked to dance fitness classes, according to a new report from the CDC.

Contact tracers linked that outbreak of cases to instructors from the February workshop, who were found to have taught classes while experiencing mild symptoms of coronavirus, such as a cough.

About 50 percent of those 112 cases were found to have been transmitted from instructors to students. That's 54 students out of the 214 found to have been exposed in the classes, or an infection rate of 26%, the report found. On average, students began experiencing symptoms about 3.5 days after attending a dance fitness class, researchers found.

The rest of the cases were linked to infected instructors and students spreading the disease to family, other friends, and coworkers, according to the report.

Research has found that people can be highly contagious and spread coronavirus without showing symptoms themselves — in this report, more than 25% of the cases were completely asymptotic.

The report's authors suggest that group fitness classes could be a uniquely risky activity, causing the outbreak even though participants in the classes only met for 50 minutes, twice a week, and had no other contact outside of class.

In particular, the warm, moist air of multiple people sweating in a small space, combined with the air flow of aerobic movement, could make is easier to transmit the viral particles, according to the report. The dance classes had between 5 to 22 students each.

Interestingly, the report also found that yoga and pilates classes held at the same time weren't linked to any cases of coronavirus. The smaller class size (between 7-8 people) and slower movement style might have lowered the risk, researchers theorized.

However, the study didn't fully account for everyone who might have attended the classes or fitness facilities, and so may have underestimated the number of infections.

As such, the researchers recommend that people avoid sweating in enclosed spaces with even small groups of people right now to avoid getting or spreading the virus.

See also:

What it's like to go to the gym in Sweden, where lockdowns never happened

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