With flu season upon us and the
constant (media) threat of an Ebola outbreak, it’s an excellent time to discuss
hygiene strategies, especially those that help ward off infectious diseases.
The most common advice you’ll likely hear is to frequently clean your hands
with soap and water and/or hand sanitizer. Either method can be quite effective
at preventing the spread of infectious diseases if used properly, but I’ve met
some people that just love hand sanitizer and use it exclusively without ever
using soap, and this can be problematic.
Hand sanitizer contains the
active ingredient ethanol (same alcohol found in liquor) which kills
bacteria by disrupting their outer cell membrane (lysis). Hand sanitizer does
not kill viruses (since viruses are not living organisms, though this topic is
often debated), but importantly hand sanitizer does inactivate most viruses,
making it a useful option to prevent the spread of viral infections.
Hand sanitizers often vary in
alcohol concentration, and this can drastically impact its effectiveness.
Typically, the higher the alcohol percentage, the more antiseptic it is. For
example, gels containing less than 50% ethanol may be less effective than gels
containing over 60% ethanol. You can also find alcohol-free hand sanitizers,
but these contain anti-bacterial agents (triclosan, for example) which are not
effective against viruses and are believed to contribute to the growing abundance of
antibiotic-resistant bacteria. I plan to write more about this topic when I
discuss anti-bacterial soap in the near future.
Several studies have shown that
the proper use of hand sanitizer can significantly reduce the chance of getting
sick, particularly during flu season. For example, a study published in June
2014 demonstrated that students who used hand sanitizer regularly each day in
addition to regular hand washing with soap and water were significantly less
likely to miss school due to illness compared to students that only used soap
and water to wash their hands.[1] This
isn’t to say that hand sanitizer is superior to soap and water washing, but
hand sanitizer can often times be more convenient, especially in situations
where a sink is not readily available.
However, it is important to note
that there is a significant difference between washing and sanitizing. Hand
sanitizer only sanitizes, meaning it typically removes > 99.9% bacteria and
viruses if used properly. But what about dirt? Grease? Toxins? Metals? Dust?
Fecal matter? Any other contaminant you can think of that comes into contact
with your hands?
Washing with soap and water is
effective at removing all of these things. Soap is not inherently
anti-bacterial, but rather it is the emulsion that forms during hand-rubbing in
water which acts as the “cleaning” mechanism. This is why rubbing your soapy
hands together for at least 20 seconds is critical because the fats in soap
form micelles which trap bacteria along with all the other contaminants on your
hands, and the water rinse at the end washes it all away.
Therefore, I believe hand washing
with soap and water should always be a first option if readily accessible and
convenient since it eliminates bacteria, viruses, and more when performed
properly. Alcohol-based hand sanitizer is an excellent second choice, but it
should not be used exclusively for all of your hand cleaning needs.
[1]
Azor-Martinez et al. Am J Infect Control.
2014 Jun;42(6):632-7
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