A patient testing positive for SARS-CoV-2 likely infected eight others at a public bathhouse in Huai'an, China—about 700 km northeast of Wuhan.
Many infectious diseases follow seasonal patterns, peaking in certain weather conditions. Influenza, for instance, thrives in cold, dry air, which is why flu seasons often wane with warmer weather.
Early speculation suggested SARS-CoV-2 might behave similarly, spreading less in hot, humid environments. However, a study by researchers at Nanjing Medical University, detailed in JAMA, challenges this idea.
The data comes from a Huai'an hospital in Jiangsu province, China. Nine men who visited the same 300 m² public bathhouse—featuring a pool, showers, and sauna—were hospitalized between January 25 and February 10, 2020. PCR tests confirmed SARS-CoV-2 in all.
Facility temperatures ranged from 25 to 41°C across areas, with ~60% humidity.
Patient 1, recently back from Wuhan, showered there on January 18. Symptoms started January 19; COVID-19 was diagnosed January 25.
Patients 2–4 showered, used the sauna, and swam on January 19; patient 5 on January 20; patients 6–7 on January 23; and patient 8 on January 24. COVID-19 symptoms (fever, cough, headache, chest tightness) emerged 6–9 days post-visit.
Patient 9 worked onsite; symptoms began January 30.
Researchers propose this "super-spreader" from Wuhan infected the others in warm (above 25°C), humid (60%) conditions.
While prior studies show some respiratory viruses transmit less in heat and humidity, this cluster indicates SARS-CoV-2 transmissibility may persist unchanged.
Limitations include unclear transmission paths. SARS-CoV-2 spreads via respiratory droplets and close contact; notably, patients 2–4 visited a day after patient 1.
Interpret cautiously, but these insights, from experts at Nanjing Medical University and JAMA, offer valuable clues on the virus's behavior.
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