How Well Do Hand Sanitizers Work? | Hacker News Reader

How Well Do Hand Sanitizers Work?

slate.com

39 pointsmhb47 comments

"In 1847, Hungarian doctor Ignaz Semmelweis discovered that washing one's hands with chlorine between deliveries practically eliminated fatal infections among laboring women. (His colleagues ignored him and later committed him to a mental hospital, where he was beaten to death by guards.)"

There's better reading on that here (link found in the original article): http://www.semmelweis.org/about/dr-semmelweis-biography/

It's amazing how stubborn we can be to changes, even positive changes.

"Today, numerous modern studies show that in randomized trials, meticulous hand-washing, when coupled with other infection control measures like surgical draping and universal gloving, reduce the rate of life-threatening infections during surgery and intensive care unit stays.

But in hospitals, outside of these clinical trials, just half of doctors and nurses regularly clean their hands before patient care, despite widespread publicity."

This is a silly comparison. During surgery (when people are literally split open) and in ICUs (when their body is profoundly damaged), the human body is unnaturally and incredibly sensitive to infection. If you've ever witnessed a surgery, you'd know that surgeons are insanely, mind-bogglingly obsessive-compulsive about washing their hands and keeping a sterile operating room.

But 99% of people in the hospital or doctor's offices are not so compromised, so it's not surprising that doctors and nurses aren't religious about hand washing "before patient care".

I've talked to doctors about this, and they point out that if they actually sanitized every time they come into contact with a patient their hands would get so dry the knuckles would start bleeding when they bent their fingers.

I hear there is this stuff called "moisturizer", which restores the moisture and oils that have been washed away by soap.

Of course, given that the moisturizer is unsanitary, the doctors and nurses would immediately have to wash it off again. :/

The hospital where my wife gave birth had "moisturizing hand sanitizer".

Sounds like a problem that could be solved. It's not all bacteria and viruses that need to be killed completely, it's mostly MRSA that is the problem. That probably doesn't live in moisturizing lotions; and once you've removed it from your hands, it's not going to come back until your touch it again.

Also, what about just wearing rubber gloves?

Atul Gawande, a surgeon and medical writer, notes in his book "Better" that hand sanitizers like Purell have not been found to have a drying effect, despite fears of the contrary.

True, for the the OR, but the New Yorker had a great article about how in many of the places in a hospital outside the OR cleanliness is often a problem, and statistically leads to a significantly higher amount of patient sickness and mortality.

Despite the clear statistics the doctor writing the piece wrote that efforts to increase hospital sanitation were met with quite a bit of skepticism, and consequently, were not followed (a sentiment echoed in this slate piece).

I wish I could link to the article, but I can't find it on the New Yorker site.

Possibly you mean this Atul Gawande article on the power of checklists: http://www.newyorker.com/reporting/2007/12/10/071210fa_fact_...

I assume you mean the checklist article that dmlorenzetti found, which I've read. That article is about people in the ICU--not merely outside the OR--where it is indeed paramount to take all measures possible to reduce the risk of infection.

If checklists are effective in reducing mortality in the ICU, then great; doctors and nurses should be insistently prodded to use them. But this shouldn't be confused with a mandate to go hand-washing crazy for all hospitals and doctor's offices. ICU patients make up a tiny percentage of all patients.

(As an aside, I am a bit skeptical of these pieces written in the popular press by experts in a certain field which criticize their colleagues. Sometimes, it's a case where the field really has settled into a bad equilibrium, and the contrarian must go outside the fold to right the situation. But often, it's simply an outlet for the contrarian to preach to an audience which doesn't have the expertise and experience to assess his claims.)

The studies mentioned don't show that using hand sanitizers is ineffective, just that mailing the sanitizers to people along with informational pamphlets is ineffective. If you actually read the first study they report finding a significant (though small) effect on respiratory infections for families that claimed to have actually used the products.

I've always wondered whether the growing modern obsession with bug killing and so forth might be counter productive.

Has anyone seen any studies they can recommend into the long term effect on our immune system?

What I'm more worried about is the claim that they kill 99.9% of germs. This would mean that the most resistant 0.1% get all the free space to grow. We're not disinfecting our world, we're creating evolutionary pressure on the germs to become resistant to our countermeasures.

Does that mean they kill 99.9% of known germ types (i.e. some are resistant). Or that it is able to kill 99.9% of germs on a known object (i.e. some random subset of germs will escape destruction for whatever reason).

I suppose the former but I've never researched.

That's interesting. I always interpret it to be 99.9% of the population on a given surface. It could be read as types also I guess.

EDIT: the article posted here http://news.ycombinator.com/item?id=1031922 seems to support the 'types' theory, although it also casts significant doubt on the validity of the claims.

...and the other 0.1% kill you...

It's an arms race.

"we're creating evolutionary pressure on the germs to become resistant to our countermeasures"

I thought that's what we were doing anyway.

Some things are easier to evolve a resistance to than others. The antibacterial measures we apply externally (rather than internally) tend to be more of the "would kill anything living" variety than the "targets specific, removable weakness of this organism". Hence, hard to adapt to.

Hand sanitizers, for example, work by immersing bacteria in alcohol, a potent organic solvent. It dissolves cell membranes and denatures proteins.

While there are bugs that can live in some pretty harsh conditions, to my mind, worrying about the bacteria in your kitchen sink spontaneously developing resistance to alcohol is like worrying about them spontaneously developing resistance to boiling water.

Possible, on the millions-of-years scale. Not exactly a big concern in this lifetime.

Another big reason resistance to alcohol (and boiling water) doesn't develop is that neither is persistent in the environment, and thus the selective pressure vanishes fairly quickly. The mutations required to resist either likely have downsides in normal environments, and thus will normally be selected against.

I share the same wonderment! In the 20 years of growing up in Kenya, I had never heard of anyone with allergies. I am baffled about how widespread allergies are in the US. Could the prolonged use of germ-killing products in the US cause this disparity? Unfortunately, I do not have statistics on allergy prevalence in Kenya vs. USA, and my wonderment is based simply on observation/experience.

[Edit]. The Hygiene Hypothesis (http://en.wikipedia.org/wiki/Hygiene_hypothesis): "In medicine, the hygiene hypothesis is a hypothesis that states that a lack of early childhood exposure to infectious agents, symbiotic microorganisms (e.g., gut flora or probiotics), and parasites increases susceptibility to allergic diseases by modulating immune system development"

[Edit2]. Statistics on the prevalence of allergies in the US: http://aaaai.org/media/statistics/allergy-statistics.asp

Alternate theory: there are different kinds of plants in the US versus Kenya. Humans happen to be allergic to the pollens that the US plants produce, and not allergic to the ones that the Kenyan plants produce.

One thing that definitely causes a lot of disease in the US is moldy buildings. Bringing in fresh air is expensive, so they just recirculate the dirty, moldy air. Then everyone gets sick, because mold in your lungs is not so good for you. (Actually, the mold gets stuck in your sinuses and then forms a film that is difficult to kill with antifungal medications. Fun! At least the building is "green"...)

There are a lot of misconceptions about the effectiveness of various hand sanitizers. What's important to know: common hand based sanitizers with a ~70% concentration of alcohol, when used properly and when left on the hands to dry (some people use the sanitizer and then wipe) are extremely effective at killing exposed bacteria, without the risk of developed resistance.

This is my first winter using (employer supplied) hand sanitizer. I have to say that so far, I haven't had any seasonal illinesses - and I don't take flu shots either - so I believe it has helped (along with regular hand washing and wearing gloves whenever I go out).

Hand sanitizers are a great example of fear-based marketing, which is very effective, just like fear-based politics.

I guess our brains are wired so that emotional content trumps informational content. (Which also explains why there always seems to be several "dramatic" posts on the front page of Hacker News like Calacanis vs. Cutts.)

Used to use alcohol (basis of hand-sanitizer effectiveness) to sterilize in hospitals (before autoclave). Had to soak for 20 minutes in pure alcohol. What difference can rubbing dilute alcohol onto your hands for 3 seconds do?

There might be a difference in how thoroughly you need to sterilize something (1) before bringing it into prolonged contact with someone's bloodstream, internal organs, etc., versus (2) before briefly touching your food / blowing your nose / ... with it.

No, no difference really, if your goal is to avoid transmitting a virus.

Yes there is. It's like the difference between going to Volgograd as a tourist today and going to Stalingrad as a member of the German army in the winter of 1942-43.

Ah, a simple metaphor we all can relate to. :)

Yeah, if I had been saying it out loud I would have been grabbing for words halfway through and would have realized it was a bit overwrought.

According to http://www.myshelf.com/haveyouheard/07/washinghands.htm, pure alcohol isn't as effective as diluted alcohol.

I've met Chuck (the first author referenced) a few times, and a couple interesting germ related items I remember him relating to me: The cleanest place in a women's bathroom is the toilet seat (nearly half of women wipe it down before use). The cleanest place in a men's bathroom is the inside door handle. Bathroom air dryers are the least sanitary - those aerosolized droplets he mentions in the article are sucked up and blown right onto your hands. Overall though, he gives the impression of someone who is absolutely not an obsessive hand washer.

You can count me as one of the unsurprised.

The fact is that the sanitizers only work while moist, and they evaporate quickly. You'd basically need to bathe constantly in it (which would destroy your skin, by the way) for it to be effective. After handling raw meat or between handling infected patients? Sure, good idea. After driving to work? It won't make a damn bit of difference once you push the elevator button, much less once you hang out in a co-worker's office or pick up your phone.

Am I the only person that finds the consistency of Hand Sanitzers just icky, I really like the feel of soap or am I just getting old ;/

I also hate hand sanitizers. I feel very dirty after using them, and feel the need to wash my hands. So I just wash my hands and skip the sanitizers.

Some are better than others.

i wash my hands with soap and hot water every time i get home to my apartment (after grabbing the door handles of the supermarket etc. etc.), and have done so since young age. i don't lick my fingers or poke myself in the eye, ear etc. without having absolutely clean hands. incidentally - and i know correlation is not always causation - i never get sick. ever. rhinovirus doesn't get me. calicivirus doesn't get me. no flu has ever gotten me.

no flu has ever gotten me.

ever? I know people say this all the time, but are you sure, you have never had the flu?

I believe them. I'm not quite that fastidious about washing my hands after being out in public, and I've only had a flu once when I was 10-12. It was a 24-hour flu and it was very unpleasant, but thankfully that's the only time I've had it.

I generally don't get sick. I catch a head cold sometimes during the season but again, it's usually pretty mild and gone the next day.

yes, i've never had any flu. the symptoms of viral infections as strong as that of the influenza virus can't go unnoticed with any healhty person. one might carry viruses around without them ever managing to infect you, though. the rhinovirus, which lives in the human crowd, is a good example of this.

The only possible problem with that approach could be if you slip up or somehow end up catching the flu by other means. It could hit you hard.

My aunt never had the flu and was barely ill most of her life due to similar behavior. A couple of years ago she caught the flu from someone and it put her in hospital for a few days and then kept her in bed/at home for about 3 months (all told).

Everything basically hit her at once.

With that said it might be you simply have a naturally higher immuno-response to viruses. I tend to get simply mild colds when the rest of my family are in bed for a week with flu :)

If you are a mom as your username suggests, that's impressive.

When our kids went to preschool, my wife and I had colds frequently. Teaching our kids the basics in hygiene at 3 years old is hard enough, but putting them in a germ hostile environment exposed them to all sorts of new germs, the result being a minor blip on their uber-immunity systems and full blown cold for ourselves.

Kids are a major vector of flu. In fact, vaccinating school age children actually prevents more deaths in the elderly than vaccinating the elderly directly.

I probably spend half my day eating my fingers. I don't use antibacterial soap or hand sanitizers (but do wash multiple times per day with regular soap). I also rarely get sick.

It's almost like this whole "immune system" thing actually works...

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