Posted by One reason Helen Branswell is such a good flu reporter is she has the best contacts. Of course this is a chicken-and-egg proposition, because she has the best contacts because she is the best flu reporter. She gets it right and she explains it the way it was told to her. [By the way, I am not on her payroll. In fact she is uncomfortable about being praised. But I don't do it for her sake. She doesn't need it anyway. My motive is to show other reporters what good flu reporting is and encourage them to do the same. And there are a number of other excellent reporters, which I try to acknowledge when I can. They are one of our most important sources of information.]
This doesn’t mean everything told to Branswell is correct, but at least you know it didn’t come over a noisy communication channel. One of her recent stories I liked least (and didn’t discuss here) was also one of her more popular, the one about flu virus in mucus remaning viable for up to 17 days on banknotes. Why didn’t I like it? Because I had no idea what it meant. Is a virus you can scarf up off a dollar bill and test to see if replicates in cell culture one that can make me sick? If it’s going to infect me it has to be picked up from the currency, presumably on my hands or fingers, and then be transferred, still viable, to some cells where it can replicate. We have known for a long time that replicable virus will last a long time on hard, dry surfaces like currency or doorknobs or arm rests, but there is also evidence that a flu virus only remains viable on a human finger or hand for a few minutes. This shouldn’t be a surprise. Skin is a biological tissue with lots of defenses against microbial invaders.
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:
“It is gobsmacking in a way that we’ve got to the 21st century and we still don’t properly understand how influenza is transmitted,” admits Dr. Jonathan Van Tam, an influenza expert with Britain’s Health Protection Agency.
Is flu often or even occasionally spread by clouds of aerosolized viruses, which can waft through the air and infect people metres removed from an ill person? Or is it mainly transmitted by viruses contained in sneezed and coughed mucous droplets which travel only short distances before gravity pulls them out of play?
And what of viruses that land on surfaces? A study, presented at a major influenza conference in Toronto in June, suggested flu viruses in mucus could live on bank notes for up to 17 days. But does contact with viruses found on money or bus poles or elevator buttons actually lead to infection? And if so, is it common or rare?
There are plenty of firmly held opinions on these questions but little science to back them. Better proof is badly needed, experts agree. (Helen Branswell, Canadian Press via Medbroadcast)
The problem is how to figure this out. When I was in medical school we knew how to do it. Human volunteers. Much of what we do know comes from experiments on people conducted in the 1960s and before. But for very good reasons this is much more difficult to do now. Ethics boards must approve these studies and they reluctant to do so when a healthy volunteer is given a virus that could make him extremely sick or even kill him. So we have been relying on animals studies.
But the information is critical, so researchers have been trying to think of ways around doing the most obvious things like challenge studies, where volunteers are deliberately exposed to controlled amounts influenza virus via various modes.
Dr. Robert Couch, a virologist at Baylor College of Medicine in Houston, did flu challenge studies in the 1960s and 1970s, exposing volunteers to virus-laced nasal drops.
Couch says he would not be willing to do the type of study that would be required to answer the key question about flu transmission – whether aerosolized viruses play a major role in disease spread. That would involve trying to infect volunteers with viruses that could get deep in their lungs and could cause severe disease.
On the other hand, he believes it would be ethically possible to conduct trials where healthy, susceptible volunteers are exposed to people who caught flu naturally and to trace under which circumstances influenza spreads among them.
“I think that would be the way to do the studies, but they would be very difficult,” Couch says. “Very difficult and very expensive.”
I’m not sure exactly why this avoids the ethical questions of a challenge study, however. It has a different “look and feel,” to be sure, but ethically it seems qualitatively the same. Ethics boards take a dim view on coercing people to volunteer for studies. They consider payment, especially to people who really need the money, a form of coercion. As for using prisoners, that’s been an ethical no-no for decades. Would I volunteer for such a study as a way to advance science? Maybe. But I’m not sure. I could get a normally mild case or even be asymptomatic, but this can also be a very, very nasty disease. Even if you don’t die from it (which most people don’t), it can knock you out for weeks or months. Do I need that?
So meanwhile we are telling people to wash their hands or cough into their elbows or caution them that surgical masks don’t work but N95 masks might — whatever. And we do all this without really having a firm basis for our recommendations. Most of these things won’t hurt and may be useful for other diseases like the common cold, even if they don’t work for flu (and they may well work for flu; we just don’t know).
So what we need is some clever way of getting this information. Any ideas? I warn you. It is a lot harder than it looks at first.
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