In that case, you have probably noticed, as I have, that the leading experts in this area tend to be rather cautious in reaching conclusions. The people who express high degrees of confidence in what they know about this matter invariably turn out to be those who really don't know that much about it. But the discussion about flu shots is really a separate one, and in the context of this discussion, what is primarily relevant as pandemic flu is concerned is that the prospect has brought increased focus on infection control measures, which in turn highlights the fact that we don't really know how flu spreads.
The Reveres have posted on this many times; maybe you'd find it more palatable coming from them:
"
In this week's Science magazine Stephen Morse calls attention to what we have been saying here for a long time. We don't really know how influenza spreds from person to person."
http://scienceblogs.com/effectmeasure/2006/11/how_does_flu_spread.php#more
Not only is this not new to me, I have said as much myself many times. But you need to look at the context of the comments. Just who it is they mean when they say "we" don't know.
The article ends saying:
There are still many questions about the spread of ordinary influenza and even more about H5N1. Tellier believes the existing evidence is more than adequate to demand the use of N95 respirators in health care institutions, not just during "aerosolizing procedures" as currently recommended by CDC but anywhere where there is coughing and sneezing from infected patients. We find it curious that he says nothing about using ultraviolet light germicidal irradiation (UVGI) units in healh care facilities since his evidence seemed to suggest it was useful and there is no comparable evidence for N95 masks. The role of hand hygiene and various kinds of personal distancing still remains unknown. Morse's plea for more investment in research in this area seems more than responable.
The debates will continue, even as a great deal of poorly founded advice is being handed out witout much questioning. Much of it, like advocating cough and hand hygiene, are at worst harmless and at best will have some effectiveness and not just for influenza. But none of it is obvious and some of it -- the contention that surgical masks are sufficient because transmission is by large droplet -- is potentially harmful.
The depths of our ignorance in this age of sophisticated molecular biology is truly impressive.
I would take this one step further. N95 masks filter out particulates >1 micron. Influenza virons are < 1 micron. The only way an N95 is going to work against influenza aerosols is by some kind of wick action. And no one has tested N95s against influenza.
In the US, respiratory protection must be NIOSH approved for the specific hazard if an employee is going to be exposed to that hazard. N95s are approved for tuberculosis, a bacterium 2 microns in size on average. In addition, TB is not highly contagious. It takes a large inoculum to infect a person.
So in the context of this article, the author is correct in saying the people making the decisions about respiratory protection are not basing those decisions on adequate science. I have voiced this opinion directly to the CDC. I am not the only one to do so and there are people there looking at the problem. Unfortunately, the current political climate is one which is suppressing information which involves employer expenses for employee safety. The failure of OSHA to enact the TB protection rule which was in the final rule stage just before Bush came into office is an example. They simply unfunded the finalizing process of the rule making.
I have also been dismayed that my colleagues assume that because N95s are approved for TB they must work for any airborne infection. My colleagues have yet to notice health care workers have been told to wear surgical masks (not designed for, not tested, and not effective against) to protect themselves from extremely hazardous airborne infections for close to a century. So it is no surprise it isn't dawning on most of them that they are making the same untested assumptions using N95s as the panacea for preventing airborne transmission of influenza and other airborne infectious diseases.
The culture of health care led to the deaths of ~800 health care workers in the SARS outbreaks. Take care of the patient the best you can, your safety is not something to stop work over and no, we just didn't prepare for this sort of thing ahead of time. You can bet had that been an industrial setting, work would have stopped soon after the first worker's death. By the same token, the OSHAct was passed in 1974 yet not really applied in the health care industry until 1989. To think nothing has changed as we plan for the next flu pandemic is appalling.
So in that context, we don't really have enough information about the spread of influenza. I beg to differ that it is the researchers with the knowledge deficit. Rather, it is the policy makers and the health care providers. And respiratory protection measures need to be tested. We most definitely have not done that research.
The researchers which have expressed the need for caution are the geneticists. Some are latching on to each new discovery as if it is a eureka moment only to find out later it wasn't quite that simple.
"
Unfortunately and as we have pointed out here too many times to count or even link to, we know very little about how flu virus is actually passed around in the community. Except here at Effect Measure, you wouldn't necessarily know this from reading most of what's printed about flu. Maybe you didn't even believe it when we said it. Well now this surprising piece of ignorance is the subject of more conversation in the flu community:"
http://scienceblogs.com/effectmeasure/2007/07/figuring_out_how_flu_gets_arou.php#more
These comments again refer to a particular "we". In this case it is the lay public. Infection control 101 says you don't just look at the presence of organisms, you have to know if it matters. If you've read my spiel about the Listerine fraud, you've heard the same thing there. So what it kills germs? What matters is does it prevent disease? And the answer is a resounding, "No".
Try it this way:
Q: So tell me how it is you want to lump all strains together and draw the conclusion that it isn't clear what role aerosols play in transmission and the data is conflicting?
A: What we don't know is what role aerosols will play when the specific pandemic emerges.
Which doesn't mean we don't really know how influenza is transmitted. Rather, it means the people making policy decisions are not paying careful enough attention to the role aerosols might play when the pandemic strain emerges.
That's great advice, skeptigirl, I'll try to remember that.
Well comparing notes here,
Your comments,
"one of your familiar attempts to establish yourself as the resident expert by casting aspersions upon anyone with the temerity to disagree with you"
and
"You seem eager to avail yourself of every opportunity to provide reminders of how qualified you are to address these issues, yet your conclusions frequently bear the flavor of dated literature, and your position clearly differs from that of some whose credentials are even more impressive than your own. Your dispute is really with them, not me. Don't shoot the messenger."
vs
My comments,
"Perhaps we are arguing semantics about what "thoroughly" means but I understand the details quite well from the research I read and in addition, I don't draw the same conclusions you did about the reason for the variable results in the studies I have read.
Give me a few minutes and I'll find some of the sources I recommend you look at. If you have some of your own, post away."
and
"You might want to read a little more about the genetic variables of pathogens within species. And maybe actually look at the research on influenza transmission. There are more than a few studies using actual human to human transmission under real conditions"
You could have taken offense to my comment, (apparently that's what you did), or you could have asked what it was I might have read that you hadn't. I can see where it sounded condescending, but had you not said the study results were conflicting, I wouldn't have thought you weren't aware of the discoveries from the genetic research on the 1918 and the HPAI H5N1 viruses and in particular on how that was affecting human to human transmission. In addition, simply clarifying the context of "who" didn't know addressed our different conclusions. No reason for any offense.
