# 4895
Science, as I’ve pointed out in the past, is messy and advances in knowledge are anything but linear. What we know, or at least - what we think we know - is constantly changing.
We often see conflicting studies published in respected journals or presented at major conferences, leaving us wondering exactly what to believe.
Depending on the study you embrace, statins either reduce pneumonia mortality or they don’t. Surgical masks are as protective as N95 respirators, or they aren’t. And Tamiflu is either lifesaving or a complete waste of time and money.
Take your pick.
One of the most vigorous subjects of debate has been the efficacy of hand washing and sanitizing as a flu preventative. And over the past year we’ve seen some studies that seem to show that it helps, and other studies that raise serious doubts.
Today, we’ve another study - presented yesterday at the ICAAC conference in Boston - (hat tip to Crof at Crofsblog for the head’s up) that suggests that using alcohol hand sanitizers `doesn’t help swine flu’.
And of all of the studies that I’ve seen so far, I can say without a doubt that . . . this one is the most recent.
You can read the details of the story in an article appearing in World News Australia at:
Alcohol rub 'doesn't help swine flu'
13 September 2010 | 07:49:12 AM | Source: AAP
But the short version is test subjects sanitized their hands with alcohol gel roughly every 3 hours for 10-weeks last fall, during the height of pandemic outbreak.
Out of 100 test subjects, 42 contracted rhinovirus (common cold) infections, compared to 51 out of 100 in the control group.
As for swine flu (H1N1), 12 in the hand disinfecting group contracted the virus, compared to 15 in the control group.
Suggesting to researchers that hand sanitizing may play less or a role in flu prevention than previously thought.
As the title of this blog suggests, this was not an entirely unexpected result.
As I wrote in September of 2009, in The Flaw In The Ointment:
Washing our hands is an important hygienic step, one that I wholeheartedly approve of (and want to encourage). And it certainly has been shown to reduce the risks of some illnesses and diseases.
But there is precious little scientific evidence to support the notion that washing our hands will protect us against influenza.
It it helps at all, it probably doesn’t help much.
Influenzas and Rhinoviruses are, after all, respiratory diseases.
While the exact mechanics of their spread are still being studied, the three main modes appear to be large droplets (coughs & sneezes), fine airborne particles, and fomites (contaminated inanimate objects we touch).
How much flu is spread by each of these methods is less clear, although large droplet spread is generally assumed to be the most common route.
In October of last year the CMAJ (Canadian Medical Association Journal) ran an article about the disconnect between the hand washing advice being offered by public health officials, and the currently available science (see Sanitized For Your Protection).
October 1, 2009
Conflict emerges over value of handwashing as a preventive flu transmission measure
Prominent microbiologist Dr. Donald Low argues that the Public Health Agency of Canada's hand hygiene recommendations "are not evidence-based."
In another study (see Effectiveness of NPIs Against ILI's), conducted prior to the emergence of the novel H1N1 virus, Allison E. Aiello’s group at University of Michigan showed that Combined hand washing and facemask use lowered risks 35% to 51% over the control group.
The use of masks alone produced nearly the same results.
Although this study did not directly study the effectiveness of hand washing alone, once again the implication here is that alcohol sanitizers and hand washing alone may not be as protective as had been touted in the past.
Of course, good hand hygiene has been linked to the reduction of illness many times. Recently a study appeared in BMC Infectious Diseases, which suggests hand hygiene can be effective even against the `common cold’.
Effectiveness of alcohol-based hand disinfectants in a public administration: Impact on health and work performance related to acute respiratory symptoms and diarrhoea
Nils-Olaf Hubner , Claudia Hubner , Michael Wodny , Gunter Kampf and Axel Kramer
Results
Hand disinfection reduced the number of episodes of illness for the majority of the registered symptoms.
This effect became statistically significant for common cold (OR = 0.35 [0.17 - 0.71], p = 0.003), fever (OR = 0.38 [0.14-0.99], p = 0.035) and coughing (OR = 0.45 [0.22 - 0.91], p = 0.02).
So which is it? Does hand washing help, or doesn’t it?
The answer to that question may depend upon exactly which virus we are talking about, your daily contacts, and even your individual environment.
For example: I suspect if you live or work around small children (whose cold & flu etiquette may be lacking) that hand washing/sanitizing might be more advantageous than for someone whose daily contacts are a bit more fastidious.
But that’s just a guess on my part.
Nonetheless, good hand hygiene remains an incredibly important health habit, and can prevent a variety of illnesses.
So I plan to continue to use my bottle of alcohol gel frequently during the upcoming cold and flu season.
Even though, right now - when it comes to scientific proof of its efficacy - the evidence is a wash.
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