No Airborne Transmission Found in Chinese HINI Outbreak
Preventing transmission by droplets is the key recommendation from researchers who analyzed the June 2009 outbreak among a tour group visiting southwestern China. Thermal scanning and health questionnaires at the Chinese airports did not detect symptomatic passengers.
Ten researchers from several Chinese centers for disease control have published a paper explaining how H1N1 flu was spread June 2-8, 2009, among a tour group of 31 people visiting southwestern China. Eleven cases of H1N1 infection were confirmed in this group, all of whom fully recovered. The researchers did not find evidence of airborne transmission in this outbreak; instead, droplet transmission occurred when the index case-patient in the outbreak, a 40-year-old female tourist, talked with fellow tourists during the trip.
The woman flew from New York City to Hong Kong on June 2 and then took two more flights to Chengdu and Jiuzhaigou, China, in the next two days. The return flight took place June 5. She first noticed her symptoms just before arriving in Chengdu, according to the researchers' paper, which has been posted prior to its print publication in CDC's Emerging Infectious Diseases journal.
Although the index case-patient and a second case-patient were feverish during the return flight, neither patient's illness was detected by thermal scanning at the airports, the authors noted. And the three symptomatic patients "did not truthfully inform health authorities of their symptoms" in the health questionnaires they filled out, so their illnesses also were not detected by that method.
Nine tour group members who were infected had talked with the index case-patient, and one airline passenger who became infected sat within two rows of her on a flight. None of the 14 tour group members who had not talked with her became ill, according to the paper. Its authors work for the Chinese Center for Disease Control and Prevention in Beijing and for additional centers in Guangzhou, Hangzhou, and Sichuan.