Movement Restrictions and Pandemic Flu
Although many assume that some sort of travel restrictions will be imposed during a pandemic, the effectiveness of such measures is often-times dismissed. We are told that models show only minor benefits because borders are porous, etc. We are told these things by epidemiologists who are clearly opposed to travel restrictions. This opposition is based, at least in part, on concern about the economic consequences of travel restrictions.
Modeling the Worldwide Spread of Pandemic Influenza: Baseline Case and Containment Interventions. Colizza, et al. 2007, PLoS Medicine.
Global travel limitations, considered a nonmedical intervention aimed at containing the virus propagation, would be unfeasible since they are so economically disruptive.
These same authors also write:
In the Text S1 we show that even drastic travel limitations delay the pandemic evolution by only a few weeks as compared to the baseline case, with almost no impact on the morbidity, as shown elsewhere.
Yet others have come to different conclusions.
Epstein, et al. 2006, The Brookings Institution
Here, we focus on the U.S. effects of international travel restrictions. Specifically, for various initial outbreaks, we compute the distribution of the First Passage Time (FPT) to the U.S. and number infected in major metropolitan areas worldwide. For a January 1 release in Hong Kong, and assuming no interventions, for example, the mean of this distribution is approx. 18 + 7 days after the first 100 cases are detected at the source. International travel restriction regimes and vaccination-type intervention are then studied. International travel restriction can increase the mean of the FPT distribution substantially. For instance, with 95 % travel restriction, the increase in FPT to the U.S. is approximately 14 days. When other international containment measures are applied, the delay can be much longer. If in the time afforded, control measures such as vaccination are instituted, the result is a significant reduction in cases worldwide and in the U.S. specifically.
More convincing, for me, is an empirical study. The shut down of all US airspace after 9/11 provided an opportunity to examine the effect of this action of influenza transmission.
Empirical Evidence for the Effect of Airline Travel on Inter-Regional Influenza Spread in the United States. Brownstein, et al. 2006, PLoS Medicine.
The flight ban in the US after the terrorist attack of September 11, 2001, and the subsequent depression of the air travel market provided a natural experiment for the evaluation of the effect of flight restrictions on disease spread. The importance of airline activity was highlighted by the delayed peak of influenza in 2001–2002 following the period of reduced flying activity. This finding is further validated by the absence of a similar delay in influenza activity in France, where flight restrictions were not imposed.
[snip]
Our results suggest that limiting domestic airline volume would have a measurable impact on the rate of spread of an influenza pandemic, and particularly on spread across regions. Because influenza pandemics have shown unusual spatial and demographic patterns as well as higher basic reproductive number due to lack of immunity, the relationship between air travel volume and domestic influenza spread may nonetheless be different in a pandemic scenario [36,37]. However, our finding that international travel influences the timing of epidemic influenza should apply directly to a pandemic scenario, where the objective will be to reduce the probability of strain introduction.
I am not an epidemiologist and am not competent to evaluate the mathematics that underlie the various models and studies. However, I do know that the influenza virus is a physical entity, not a miasma. It is carried by a vector. In the event of a pandemic, that vector will be people. Stop the vector and you stop the spread of the virus.
So, who are the experts on controlling human movements? Not epidemiologists, that's for sure. The TB guy fiasco should have convinced us of that.
So, who ya' goin' call?
The Military. That's who.
Feb. 1, 2006
By Sgt. 1st Class Gail Braymen, USA
Special to American Forces Press Service
Well before news headlines started reporting growing numbers of both sick birds and sick people, U.S. and Canadian military officials decided to focus joint exercise efforts on the pandemic influenza scenario. "Since that time, a tremendous amount of energy has been expended to prepare for the eventuality that this is a very plausible and a very dangerous threat," Pino said.
Exercise attendees analyzed topics such as public health care, maintaining civil order and providing continuity of government and private operations in case of widespread infection and worker absenteeism.
"NORTHCOM will not be running the show in the event of a pandemic," said Dave Wilkins, the NORTHCOM exercise facilitator. "We will be taking guidance and requests from other agencies, such as the Department of Homeland Security, via the secretary of defense."
[snip]
Exercise participants agreed that the United States will not be able to keep an influenza pandemic from entering the country. Instead, the common goal of all agencies represented is to contain and mitigate the consequences of a pandemic as much as possible.
[snip]
Although NORTHCOM is prepared to take on more duties if requested by the president or secretary of defense, the command's primary mission will remain its "non-negotiable contract with the American people to defend the homeland," Bassani said. "We're here to support and defend the nation."
Although the spokesman for NORTHCOM is very modest about NORTHCOM's role in a pandemic, other documents suggest an important role for the military in controlling movements during a pandemic.
(Presented by the United States of America)
Tenth Meeting of Civil Aviation Authorities (RAAC/10), Caracas, Venezuela,
13-15 June 2007,
Agenda Item 8: Other Matters
1.5 In addition to developing pandemic response plans at each level of government, our different departments are working together to establish a national policy on entry/exit screening to impede the spread of the disease. Our planning assumptions are based largely on guidance provided by the HHS Centers for Disease Control and Prevention (CDC):
• The pandemic could start at any time, at any location.
• Once the virus comes to the United States, we may experience
simultaneous outbreaks in different locations, with waves lasting 6-8 weeks at a time in a given location.
• The total pandemic may last from 12 to 18 months or longer.
• Not all regions may be affected simultaneously.
• As much as 40% of the workforce may be absent at the peak of the localized outbreak.
• Air travel will be reduced by the effects on aviation infrastructure and travel restrictions (either self-imposed or government-imposed).
1.6 The FAA’s Air Traffic Organization (ATO) has developed a joint CONOPS with TSA, the Customs and Border Protection Agency (CBP), CDC, and the U.S. Northern Command (NORTHCOM) to coordinate the operational aviation response to a pandemic.
[snip]
1.7 The CONOPS focuses on the activation of a Specialized Aviation Response Cell (SARC), which will support coordinated command and control among the participating government agencies for aviation operational response activities. To provide a fast response to pandemic emergencies, the SARC is limited to only essential agency representatives empowered by their agencies to make quick decisions in response to a fast-moving situation. The members of the SARC will probably include FAA, TSA, CBP, CDC, DOS, and the Department of Defense.
What kind of quick decisions are likely to be made that require the use of the military?
NEHC CONFERENCE 2007
Navy Pandemic Influenza Council
Revised 3/02/07
CAPT MICHAEL MACINSKI, MSC, USN
Movement Management support requirements may be significant including the ability to manage DOD airlift operations, augmentation of FAA personnel should they be impacted by influenza, surface transportation management should movement restriction be imposed, and the implementation of any directed restrictions on interstate travel.
Well that's pretty clear. The DoD will be involved in movement "management" which may include restrictions on interstate travel.
This should not be a surprise. The President of the United States has said that he will consider quarantining entire US cities in the event of a pandemic. Shutting down US airspace and blockading interstate highways at key points is a million time easier than quarantining a city.
I know that many people are opposed to movement restrictions. They are concerned that people on the wrong side of the barricade will not get food and medicine. And rightly so. However, the answer is not to suggest that movement restrictions are intrinsically doomed to failure - they aren't. Depending on geography and how quickly they are imposed, movement restrictions may be quite useful. Saying otherwise has not convinced the POTUS or the Secretary of Defense, as the documents above demonstrate.
Even if the Feds decided to do nothing, movement restrictions would still be imposed - by governors, by mayors, by sheriffs, by terrified citizens with shotguns. It's just human nature. To expect otherwise is just plain unreasonable.
I am not opposed to movement restrictions - provided that people are told ahead of time, loud and clear, that they will be imposed during a very severe pandemic. This should provide incentive for prepping. It would also provide incentive for the residents of megacities to demand pre-positioned stockpiles of food and medicine.
Movement restrictions done right may provide us months of extra time to prepare. Movement restrictions without warning will lead to unnecessary tragedy.
Saturday, December 8, 2007
