Emerg Infect Dis. Lack of Airborne Transmission during Outbreak of Pandemic (H1N1) 2009 among Tour Group Members, China, June 2009

[Giuseppe]

Lack of Airborne Transmission during Outbreak of Pandemic (H1N1) 2009 among Tour Group Members, China, June 2009 (EID, abstract, edited)

[Original Full Document: LINK. EDITED.]

DOI: 10.3201/eid1510.091013

Suggested citation for this article: Han K, Zhu X, He F, Liu L, Zhang L, Ma H, et al. Lack of airborne transmission during outbreak of pandemic (H1N1) 2009 among tour group members, China, June 2009. Emerg Infect Dis. 2009 Oct; [Epub ahead of print]

Lack of Airborne Transmission during Outbreak of Pandemic (H1N1) 2009 among Tour Group Members, China, June 2009

Ke Han,1 Xiaoping Zhu,1 Fan He,1 Lunguang Liu, Lijie Zhang, Huilai Ma, Xinyu Tang, Ting Huang, Guang Zeng, and Bao-Ping Zhu

Author affiliations: Chinese Center for Disease Control and Prevention, Beijing, People?s Republic of China (K. Han, F. He, L. Zhang, H. Ma, G. Zeng, B.-P. Zhu); Guangdong Center for Disease Control and Prevention, Guangzhou, People?s Republic of China (K. Han); Zhejiang Center for Disease Control and Prevention, Hangzhou, People?s Republic of China (F. He); and Sichuan Center for Disease Control and Prevention, Sichuan, People?s Republic of China (X. Zhu, L. Liu, X. Tang, T. Huang)
1) These authors contributed equally to this article.


During June 2?8, 2009, an outbreak of influenza A pandemic (H1N1) 2009 occurred among 30 members of a tour group in China. To identify the mode of transmission and risk factors, we conducted a retrospective cohort investigation. The index case-patient was a female tourist from the United States. Secondary cases developed in 9 (30%) tour group members who had talked with the index case-patient and in 1 airline passenger (not a tour group member) who had sat within 2 rows of her. None of the 14 tour group members who had not talked with the index case-patient became ill. This outbreak was apparently caused by droplet transmission during coughing or talking. That airborne transmission was not a factor is supported by lack of secondary cases among fellow bus and air travelers. Our findings highlight the need to prevent transmission by droplets and fomites during a pandemic.

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[gsgs]

Re: Emerg Infect Dis. Lack of Airborne Transmission during Outbreak of Pandemic (H1N1) 2009 among Tour Group Members, China, June 2009

I wished there were more such studies.
Is it so difficult ? Just extensive questioning, no lab work, so maybe not
so attractive for researchers.
Except in China, where they have more (wo)manpower


now test who transmits flu by coughing, speaking


hold your breath when someone speaks to you or coughs at small distance


well, maybe they don't speak so much in the airplane and bus, and
there was good air-circulation and filtering.
So I won't yet rule out airborne transmission

[mixin]

Re: Emerg Infect Dis. Lack of Airborne Transmission during Outbreak of Pandemic (H1N1) 2009 among Tour Group Members, China, June 2009

This issue, then, is just about small particle spread versus large particles?

If I understand correctly, large virus particles tend to stay in the upper respiratory tract and the smallest ones are the only ones that can go deep into the lungs. Upper respiratory infections are mostly milder and since this virus is considered mild, then droplet transmission makes sense?
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(I pulled these snips from the full report.)

She started coughing before she boarded the flight from Chengdu to Jiuzhaigou on June 3 and continued to cough during the entire tour and after she returned to Chengdu.

They traveled to various tourist attractions by bus and participated in group activities during the next 3 days. The air conditioning system in the tour bus mixed 70% recirculated inside air with 30% outside air, filtered it, and delivered it into the bus through air outlets above the passenger seats. A vent at the back of the bus continually exhausted air from inside the bus.

During the trip, doors were shut and windows were sealed to conserve energy. While traveling among the various tourist attractions, the group was together on bus rides for a total of 6 hours and 50 minutes.

She had extensive interactions with other members of the group, who talked with each other, helped each other take pictures, gave chewing gum to each other, had group meals together, and stayed in the same hotel.

When we evaluated the contact patterns of the tour group with the index case-patient, we found that for the 16 tourists who had talked with the index case-patient from close range (under 2 m) for >2 minutes, the attack rate was 56%, whereas none of the 14 tourists who did not talk with her became ill. Members of the tour group who had talked with the index case-patient for >10 minutes were almost 5? as likely to become ill than those who had talked with her for 2-9 minutes.

None of the 14 tour group members who had not talked with the index case-patient became ill, (even though) they did report other interactions with her, such as dining at the same table, sitting within 2 rows on the same flight or bus ride, and receiving chewing gum from her. Moreover, 3 of these 14 uninfected passengers had sat within 2 seats of the index case-patient during the bus rides but had never talked with her from close range.

The virus spread by droplet transmission when the index case-patient was talking with her fellow tourists. The findings of our investigation highlight the importance of preventing droplet transmission during a pandemic.

http://www.cdc.gov/eid/content/15/10/pdfs/09-1013.pdf

[Commonground]

Re: Emerg Infect Dis. Lack of Airborne Transmission during Outbreak of Pandemic (H1N1) 2009 among Tour Group Members, China, June 2009

from pdf file at Post #1:

The index case-patient left New York City, United States, on flight CX841 at 12:00 AM (midnight) June 2 and arrived in Hong Kong at 2:00 PM on the same day. She transferred to flight CA428 (Boeing 757), which departed Hong Kong at 7:25 PM and arrived in Chengdu at 10:00 PM. On June 3, she and her family members joined the tour group at the Chengdu Airport and boarded flight CZ6659 (Boeing 757), which departed Chengdu at 12:25 PM and arrived at Jiuzhaigou (33?15′55′′N, 104?13′35′′E; average altitude 2,930 m) at 1:10 PM.
-snip-
The index case-patient began having chills at ≈9:00 PM during her flight from Hong Kong to Chengdu. She started coughing before she boarded the flight from Chengdu to Jiuzhaigou on June 3 and continued to cough during the entire tour and after she returned to Chengdu.

To me, that is pretty quick. Going from chills to coughing - between 9pm and 12:25 the next day.

[mixin]

Re: Emerg Infect Dis. Lack of Airborne Transmission during Outbreak of Pandemic (H1N1) 2009 among Tour Group Members, China, June 2009

We don't talk a lot about the importance of chills. Sometimes we have them; sometimes we don't. I wonder why?

[Laidback Al]

Re: Emerg Infect Dis. Lack of Airborne Transmission during Outbreak of Pandemic (H1N1) 2009 among Tour Group Members, China, June 2009

This is an important study. I agree with gsgs that it should not be that difficult to conduct similar analyses.

Certainly makes a strong case for wearing masks.