UPDATED 1800hrs EST: The latest news reports out of NZ indicate that unaffected passengers have been allowed off the plane are now going through customs. As expected, authorities now believe the sick passengers probably contracted seasonal H3N2 influenza while in Japan.
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While we wait for an update (see update) on the Boeing 777 currently quarantined on the tarmac at Auckland airport with scores of passengers complaining of flu-like symptoms (see New Zealand : Airline Passengers Quarantined) this would seem an opportune time to look back at some of what we’ve learned about airplanes, airports, and influenza over the years.
What follows are excerpts from previous blogs, you can follow the links to read them in their entirety.
As I mentioned in my last blog, New Zealand has a very aggressive influenza pandemic plan, and I wrote about their drills and preparations back in October of 2008.
New Zealand: Testing Pandemic Quarantine Plans
New Zealand, being an island nation, is one of the few countries that believe they have at least the possibility of blocking a pandemic virus from entering their borders.
It is an ambitious goal.
And the odds of carrying it out successfully are pretty long.
How far they will go to try to block a pandemic virus from entering their country hasn't been decided yet by their Ministry of Health (MOH).
In their FAQ on pandemic influenza, the question is answered this way:
Will New Zealand stop travellers from coming into the country in an effort to stop the spread of disease?
Because we are an island nation, active management of the border (i.e. limiting arrivals from affected areas to allow us to impose effective on-arrival measures) needs to be considered among the range of options as we plan our response. Other countries are also considering border management options.
Any final decision on border management will be made by the Government with input from a range of government departments.
The details of how New Zealand might manage its borders are laid out in the National Health Emergency Plan: New Zealand Influenza Pandemic Action Plan 2006.
But whether the goal is to try to stop the virus from entering the country, or to simply slow the introduction while a vaccine is being produced, it takes planning and training.
The enormity of the job of interdicting infected passengers was the subject of a blog I wrote just one month before the outbreak of the 2009 H1N1 pandemic virus.
How The Next Pandemic Will Arrive
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There is a lot we don't currently know about the next pandemic. We don't know when it will arrive. We don't know what virus will cause it. And we don't know how bad it will be.
But there is one thing almost certain.
It will arrive in most countries by airplane.
The video above, which as been making the rounds for several months, was made by ZHAW (Zürcher Hochschule für Angewandte Wissenschaften) or The Zurich University of Applied Sciences.
It is a simulation (using real data) showing 24 hours of air traffic around the world. Notice how the level of activity follows the daylight.
Every year there are more than 17,000,000 commercial airline flights (data from year 2000 - it's probably higher now) that carry hundreds of millions of passengers each year.
As far as the transmission of the influenza virus aboard an airliner, in May of 2010 we saw a study in the BMJ that looked at that very topic. And as the fates would have it, this study was done on a plane flight into the same airport in Auckland, New Zealand.
Note: Given the incubation period of most respiratory viruses, those who are symptomatic on today’s flight almost certainly were exposed and infected prior to boarding the flight.
Friday, May 21, 2010
BMJ: Flu Transmission Risks On Airplanes
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BMJ 2010;340:c2424
Research
Transmission of pandemic A/H1N1 2009 influenza on passenger aircraft: retrospective cohort study
Michael G Baker, associate professor1, Craig N Thornley, medical officer of health2, Clair Mills, senior lecturer3, Sally Roberts, microbiologist4, Shanika Perera, medical officer of health2, Julia Peters, medical officer of health2, Anne Kelso, director5, Ian Barr, deputy director5, Nick Wilson, associate professor1
I’ve reproduced portions of the abstract below. The entire study is available online at the BMJ.
Objectives To assess the risk of transmission of pandemic A/H1N1 2009 influenza (pandemic A/H1N1) from an infected high school group to other passengers on an airline flight and the effectiveness of screening and follow-up of exposed passengers.
<SNIP>
Setting Auckland, New Zealand, with national and international follow-up of passengers.
Participants Passengers seated in the rear section of a Boeing 747-400 long haul flight that arrived on 25 April 2009, including a group of 24 students and teachers and 97 (out of 102) other passengers in the same section of the plane who agreed to be interviewed.
Conclusions A low but measurable risk of transmission of pandemic A/H1N1 exists during modern commercial air travel. This risk is concentrated close to infected passengers with symptoms. Follow-up and screening of exposed passengers is slow and difficult once they have left the airport.
And lastly, a long hard look at attempts by countries to detect and isolate infected travelers during a pandemic. As countries discovered in 2009, travel restrictions are very difficult to implement, and will likely fail in the long run.
Travel-Associated H1N1 Influenza in Singapore
(Thermal Imaging in 2003)
The idea sounds simple.
By screening passengers for fever when they arrive via airplane (or boat or train) from another country you can hopefully reduce the number of infected passengers that enter during a pandemic.
In reality, it isn’t simple at all.
Today a summary from NEJM Journal Watch of a new study that has been published, ahead of print, in the CDC’s EID Journal entitled:
Epidemiology of travel-associated pandemic (H1N1) 2009 infection in 116 patients, Singapore. Emerg Infect Dis 2010 Jan; [e-pub ahead of print]. Mukherjee P et al
Travel-Associated H1N1 Influenza in Singapore
Airport thermal scanners detected only 12% of travel-associated flu cases; many travelers boarded flights despite symptoms.
Travelers play a key role in spreading many infections, including influenza. Such was the case with the spread of 2009 H1N1 influenza to Singapore, a major travel hub serving 37 million air passengers annually.
