What forms of knowledge are being brought to bear in public health responses to the current pandemic? Stephen and I have distinguished between an “archival-statistical” model of knowledge production that is characteristic of much of traditional public health decision-making, on the one hand, and an “enactment” model that is brought to bear in efforts to manage risks whose likelihood cannot be calculated based on archival knowledge. One source of contemporary methods of enactment (such as scenario planning and catastrophe modeling) was US civil defense. But these methods have reached into many new domains. As Stephen writes in “Enacting Catastrophe“:
“Across multiple sectors, and over many decades, enactment was invented and then redeployed in response to situations in which the archival-statistical model proved inadequate to new problems.”
In the development and implementation of pandemic preparedness plans, one finds interesting hybrids of enactment and archival-statistical methods for generating knowledge about current needs. For example, we might take the use of archival data about the 1918 flu pandemic in plans for non-pharmaceutical interventions, such as school closure, banning of public gatherings, and isolation of patients. Based on quantitative, comparative analysis of mortality rates in different US cities during the 1918-1919 pandemic, historian Howard Markel and colleagues have developed recommendations for strategies to delay the spread of flu in cities in order to extend the time available for the development and distribution of therapeutics and vaccines. They write:
“In summary, the 21 cities that had earlier PHRT [public health response time] and the most sustained and most days of nonpharmaceutical interventions had a statistically significant reduction in excess pneumonia and influenza mortality rates compared with the 21 cities that had later PHRT and fewer days of nonpharmaceutical interventions.”
St. Louis provides a model for an early, “layered” strategy of nonpharmaceutical intervention that corresponded with lower excess death rates. Such historical research has been taken up by CDC along with theoretical modeling in its development of mitigation plans. So, on the one hand, we have a kind of “worst-case scenario” thinking in which knowledge of current vulnerabilities and necessary mitigation measures are developed through enactment; but that enactment is based on archival data about an historical event. We might ask: is 1918 the right event to serve as exemplar for contemporary pandemic preparedness?
I don’t think so.
First, there are 4 levels of pandemic planning that people in the planning stages discuss, but generally don’t distinguish in press statements or interviews: 1. generic emergency (earthquake), 2. generic infectious diseases (this is like a catch-all category), 3. specific infectious disease (influenza), and 4. specific type or strain of disease (H5N1). The plans that went into effect were category 3. Perhaps, in the early stages, it’s always a category 2 response first, until the disease is specified. I know that there were no H1N1-specific plans, so they had to rely on what they had planned out for H5N1. However, since the mortality in H5 is 60%, the pandemic levels based on the H5 scenario didn’t exactly fit. There was slippage.
Second, modeling for a flu pandemic is currently generally based on the 1918 flu (for a worst-case scenario), 1968 (for a “better-case” scenario), and/or 1957 (either lumped with 1968 or taken as a third ‘case’). I also think that the enactment model might be starting to shift its foci. (But I’ll get into that more in person.)
Third, there is some wrangling in the epi community about whether or not mitigation measures (either in 1918 or now) actually worked. Hand-washing, for example, has been shown to be almost entirely ineffective against the flu. Apparently, or so the scientists tell me, it’s because particles need to hit the lungs themselves to cause a severe – and lethal – case of the flu. Touching something and then touching your nose, mouth or eyes doesn’t give you the flu (but it will give you a cold). Breathing in tiny droplets (less the 5 microns) does. Surgical masks are better than nothing, but not as good as the more expensive and less readily available N95 masks. There is also less “evidence” that school and business closures stop the spread.
What does stop the flu? I asked. Immunity, was the answer I received from both a virologist and an epidemiologist.
My question is, then, why do the WHO and CDC keep telling people to wash their hands? Symbolic act? Talisman that calms the jittery nerves of the average citizen? A “just in case” public health measure?
My other question: how long will it take for this event to be incorporated into future enactments and archival-statistical knowledge? I feel as thought the archive and stats are almost self-creating with the daily case numbers and spread maps.
Interestingly, this editorial in NYTimes makes exactly the opposite argument: hand-washing is very effective, masks are ineffective. http://www.nytimes.com/2009/05/03/weekinreview/03rosenthal.html?_r=1&hp
The author’s argument seems to be supported primarily by anecdote and claims to personal authority. Are there definitive research studies out there?
It’s been one of the most striking things to me about influenza preparedness planning: so much science and technology directed towards detection and tracking of outbreaks, but so little that can be done to stem the spread beyond traditional public health measures (isolation, etc.).
Apparently, hand-washing is really effective for SARS-related corona virus and rhinoviruses. Not so, the influenza viruses. Reingold said that he has the citations, if you want to see them.
Yes, handwashing will only protect partially (at best).
Here’s what Palese recently said in an interview regarding hand-washing and face masks:
How effective are hand sanitizers in preventing transmission of swine flu?
Hand sanitizers are effective if used correctly — they have alcohol in them. Hand washing helps, too, but there is also an aerosol component to the influenza virus. We can keep our hands in our pockets and still get influenza. At the same time, we should have hand hygiene as much as we can. Besides conferring some protection against swine flu, it helps against other problems such as common colds and intestinal bacteria.
Do face masks do any good in protecting people from swine flu?
Face masks do one thing — they protect people in terms of preventing other people from getting close to them. So you get a sphere of privacy from wearing a mask, but it’s largely psychological. The masks do help if someone sneezes right at you. However, the pore size of these masks lets viruses go through. Again it is not a clear-cut yes or no. There is some benefit, but there is not as much benefit as we would like.
… and even “immunity” is no guarantee. Especially in the elderly population, the degree of protection is not very good despite vaccination. The impact of current interventions on the spread of seasonal flu is not very satisfying. Extrapolate to a pandemic …
Just to clarify: it seems that there is an important distinction to be made among types of “non-pharmaceutical interventions”: the Markel, et al work is not about voluntary individual actions like donning masks or washing hands as the key nonpharmaceutical interventions that had effects in 1918; rather it focuses on collective, government enforced interventions such as school closures, canceling public gatherings and quarantine. This comparative historical research on diverse actions taken by cities in 1918 – and their diverse effects – is supposed to guide current urban decision makers (such as the Fort Worth school district; or Mexico City public officials) in figuring out when to ban public gatherings or other sites of physical interaction. Markel et al conclude that cities that engaged in early, sustained intervention (imposed in a “layered” order) had lower mortality rates.
Reading through all this, I think I tend to read Andy’s question in a slightly different way, and to think about the answer differently. 1918 is the “right” event because: (1) it *was* an event of pandemic influenza with high mortality rates and thus a certain kind of response across many communities; (2) it is probably unique (among such events) in the amount of data we have about urban response. This second point seems to me singularly important. You can set up experiments, presumably, to test the effectiveness of hand washing or face masks. But you can’t set up experiments to test the actual disciplinary lock-down of a city in the face of a highly transmissible pathogen with high fatality rates. So for the specific questions Merkel et al were asking I would be inclined to think that 1918 might be the only game in town — but maybe others know more about the response to the subsequent 20th century pandemics and their relevance for assessing this kind of disciplinary response…