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Circular Reasoning

This is perhaps the stupidest quote I’ve heard from someone supposed to smart in a long time:

“By definition, pandemic influenza will move around the world,” Chan said in the call today. (Margaret Chan, WHO Deputy-General)

“By definition, a nuclear holocaust is the catastrophic introduction of nuclear explosions across the world, so it can’t be stopped.”

“By definition, winning is not losing. So if we win we cannot lose, therefore we will win.”

Yeah, I’m not interested in the definition of “Pandemic Flu Outbreak.” I’m interested in not having a lot of people die. In a previous post I quoted the Wikipedia article on the 1918 Pandemic where we find judicious use of quarantines and controlling borders does work, at least for island nations. Chan never actually cites any documentation showing closing borders doesn’t work.

Well, I went out a found a couple and they say non-pharmaceutical interventions can work:

At the international level, experience in past influenza pandemics indicates that screening and quarantine of entering travelers at international borders did not substantially delay introduction, except in some island countries. Similar policies, even if they could be implemented in time and regardless of expense, would doubtfully be more effective in the modern era of extensive international air travel. WHO instead recommends that travelers receive health alert notices, although entry screening may be considered when the host country suspects that exit screening at the traveler’s point of embarkation is suboptimal; in geographically isolated, infection-free areas (e.g., islands); and where a host country’s internal surveillance capacity is limited (2).

WHO recommends consideration of exit screening by health declaration and temperature measurement for international travelers departing countries with human infection at phases 4, 5, and 6. Exit screening in affected countries is a better use of global resources: fewer persons would need to be screened, the positive predictive value for ill persons detected would be higher, and transmission on conveyances, such as aircraft, would be reduced. Exit screening is disruptive and costly, however, and will not be fully efficient as influenza viruses can be carried by asymptomatic persons who will escape detection during screening (2,3). As was true for SARS, the principal focus of WHO-recommended nonpharmaceutical interventions is not at international borders but at national and community levels (4).

Another source:

None of this is any big secret – you can read it all in much more detail in the pandemic flu national framework, or the joint RCGP-BMA pandemic flu guidance for GPs – and much is widely known. But as journalists around the country scramble for the facts, it’s worth remembering a few key points:

1. Interventions can be limited. Closing the borders doesn’t work – the Government’s modelling suggests even a travel ban that is 99.9% effective would only delay the arrival of a pandemic by two months at the most. Modelling in the national framework also suggests that widespread public use of face masks, cordons sanitaires to isolate affected communities and even a blanket ban on large public gatherings are all likely to be relatively ineffective.

Targeted use of antivirals and stringent infection control and hygiene measures are likely to be more useful – but the bottom line is, until an effective vaccine is developed, there’s little than can be done to stop it spreading.

2. Pandemics last a long time. While each one is different, the best modelling suggests that it will reach the UK between 4-8 weeks after it begins in the country of origin. Once in the UK, ‘it is likely to spread to all major population centres within one to two weeks, with its peak possibly only 50 days from initial entry.’ There may also be subsequent pandemic waves – the 1918 pandemic lasted 18 months. Should we flee to the hills, I used to be asked at the HPA. Not unless you’re willing to stay there indefinitely, we replied…

So, exit screening for international flight passengers, with some entry screening. Local and community level nonpharmaceutical interventions as the main focus. Quarantines and border closings as secondary tools to delay spread of the disease (up to two months) in order to have that much more time to develop a vaccine or stock up on Tamiflu.

Just some thoughts.

Update (Via King Banaian), NYTs suggests what those local and community nonpharmaceutical interventions might look like:

Scientists are still studying the 1918 pandemic, the deadliest of the 20th century, looking for lessons for future outbreaks — including the possibility that H5N1, the avian influenza virus, could mutate into a form spread easily from human to human. This month, researchers published two new studies in The Proceedings of the National Academy of Sciences comparing public-health responses in cities like St. Louis and Philadelphia.

Using mathematical models, they reported that such large differences in death rates could be explained by the ways the cities carried out prevention measures, especially in their timing. Cities that instituted quarantine, school closings, bans on public gatherings and other such procedures early in the epidemic had peak death rates 30 percent to 50 percent lower than those that did not.

“It had been received wisdom that these interventions didn’t work,” said Dr. Richard Hatchett, the lead author of one of the studies, “because they looked at the variability between cities and concluded that there was some other factor than the interventions that caused the differing outcomes.

“That we were able to go back and ask the right questions,” Dr. Hatchett said, “is a function of a lot of modeling work that we did previously.”

Dr. Hatchett, who is a researcher at the National Institutes of Health, said the findings might hold lessons for the 21st century. “When multiple interventions were introduced early, they were very effective in 1918,” he said, “and that certainly offers hope that they would be similarly useful in an epidemic today if we didn’t have an effective vaccine.”


3 Responses

  1. A buddy of mine said his pharma company declined to sell the Mexican government various treatments they had for this flu. The rationale was that they would make far more money holding onto their supply until the flu hit hard in the US – because we pay more for these treatments. (They also had to hold a reserve for China because they make the treatments there and without a large stockpile they feared the government would seize the factory!)

    So it seems we wealthier Americans with a quasi free market health system will benefit more than the other countries with nationalized health care…

  2. Socialism is to blame. I like it.

  3. It’s Swine/11!

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