Hand hygiene removes influenza virus

HandWashing_250pxDispensers of alcohol-based rubs are appearing in public places in an attempt to reduce the spread of pandemic influenza. Are these effective at removing virus from hands?

In a recent study, the hands of twenty vaccinated, antibody-positive volunteers were contaminated with 10,000,000 TCID50 of a 1999 seasonal H1N1 influenza virus strain (see this post for an explanation of TCID50). The virus solution was allowed to dry on the hand for 2 minutes. Then one of five different treatments were done:

  • Soap and water handwashing
  • Use of a gel containing 61.5% ethanol
  • Use of a gel containing 70% ethanol and 0.5% chlorhexidine
  • Use of a gel containing 70% isopropanol and 0.5% chlorhexidine
  • No treatment

The amount of influenza virus on hands before and after treatment was then determined by determining infectivity in cell culture and by measuring viral RNA by polymerase chain reaction (PCR).

There was an immediate reduction in culture-detectable and PCR-detectable virus after the 2 minute drying period. In 14 of 20 individuals, virus was detected by cell culture (average reduction of 1,000–10,000 TCID50/0.1 mL), and in 6 of 20 no viable H1N1 virus was recovered. These results show that the human hand is a hostile place for influenza virus, possibly because of the combination of drying and natural defenses such as skin oils.

All four hand treatments showed marked antiviral efficacy: 14 of 14 individuals had no virus detected by culture or PCR. Soap and water washing was slightly better than the alcohol-based treatments, but the differences were very slight: 1– 100 virus copies/mL. Nevertheless, alcohol-based treatments are likely preferable because they are faster and more portable than washing with soap and water.

This study is not perfect – the number of subjects was small, and the effects of the treatments on different strains of influenza virus was not determined. Nevertheless, the findings that simple washing with soap and water or alcohol-based gels is effective at removing influenza virus from hands is likely to help prevent transmission of infection.

Grayson, M., Melvani, S., Druce, J., Barr, I., Ballard, S., Johnson, P., Mastorakos, T., & Birch, C. (2009). Efficacy of Soap and Water and Alcohol‐Based Hand‐Rub Preparations against Live H1N1 Influenza Virus on the Hands of Human Volunteers Clinical Infectious Diseases, 48 (3), 285-291 DOI: 10.1086/595845

Comments on this entry are closed.

  • davidstuarthill 17 July 2009, 4:46 pm

    The problem is that no one listens including the media. Swine flu if it mutates to something equivalent to the Spanish flu of 1918/1919 (Spanish flu was a swine flu variant) has the same potential to kill humans on an unprecidented scale as it did 90 years ago. The problem is that both swine and avian are constantly mutating into something different. So by the time you have isolated and made a vaccine for the last one, it has changed again and circumvented the old guard and becomes useless. The problem is that this happens all the time and where drugs become irrelevant. The reason, it takes three months to develop an antidote and 6 months to mass produce and distribute it (a logistic nightmare in itself alone) and where on average therefore the vast majority have to wait 9 months for the cure. The problem is that even in slow coach travel times 1918, the Spanish flu which took between 20 and 100 million lives worldwide (there is no authoritive number but where it is estimated between the two), did its deadliest between week 14 and week 26, some 12 weeks at least before the masses would ever receive the drug cure presently. The 1918 killer flu had a very similar circumstance as today, a mild version before the deadly version arrived in the fall of 1918 with a vengeance. The only way that this deadly killer can be stopped therefore, if anyone is listening out there, is through a complete overhaul of modern farming and husbandry methods and to give considerable financial help to those who breed the livestock that we all eat. Basically as a single example, just stop them sleeping with the animals on cold nights in the tropics as this is how the flu virus passes from pig to chicken to man – eventually; and where the pig is the receptive incubator. Simply give them a heater and fuel, a much cheaper option that global suicide in both human and econmic terms as it will be. For the ‘Tropics’ are where some of the most eminent virologists and micribiologists in the field say is the place where the killer virus will emerge.The philosophy of not letting it happen in the first place. The drugs strategy is futile and it is only a matter of time before the killer strain that will kill literally 100s millions appears. The problem is that the vast profits of drug companies and the government's ignorance to the real facts will be the nails in all our coffins. The statistics and potential speak for themselves,

    World Population 2 billion – 1920
    Range of deaths
    20mil/2billion = 1 in 100
    100mil/2billion = 5 in 100

    World Population now at 6.8 billion now equates to,
    1 in 100 – 70 million min. today
    5 in 100 – 340 million max. today
    But, these figures could well be higher, as rapid world transit now makes for faster and wider transmission than in 1918.
    I therefore say lets start now as I have been saying for the past three years and defeat this mass killer like no other by field work and not the futile drugs strategy that will do very little indeed to save lives. For presently we are all fooling ourselves.

    If we put only £50 billion into this field work globally ( a small price for the human nightmare and financial melt-down that a global equivalent to Spanish flu would bring),we could eradicate the situation but where this £50 billion will no doubt end up alternatively in the pockets of the large pharmaceutical companies with little effect whatsoever. Get real everyone before it is basically too late and I am not joking – force governments to change their strategies from something that is impotent presently to something that will eradicate the problem at source. Common sense really but where currently no one seems to have any.

    Worryingly also is the fact that as examples of other problems on the horizon is that the United States makes only 20 percent of its flu vaccines it uses and my country Britain makes zero percent of its flu vaccines, as all its flu vaccines are produced abroad. When a killer pandemic happens it will be hard for the producing countries to release any before their own people are serviced. Little known but true (Michael Osterholm, director of the Center for Infectious Diseases Research and Policy at the University of Minnesota – 16.07.09).

    I have been stopped from putting these comments and facts out by the media before. Let’s hope that minds are fully opened now and that the real solution can be heard and not just the bottom-line for drug companies!

    Dr David Hill

  • Teeny 22 July 2009, 3:49 am

    Going by the last published figures on WHO (http://www.who.int/csr/don/2009_07_06/en/index….) it seems that there is a 0.45% mortality rate. I'm not completely certain what the situation is like in other countries but here in the UK the vast majority of deaths were not linked to H1N1.
    By comparison, H5N1 has a 60% mortality rate (http://www.who.int/csr/disease/avian_influenza/…).
    Worst case scenario the virus mutates to a form that can easily be transmitted from human to human and retains its lethality in a full-blown pandemic. This is when the government should be pouring their cash into forming a vaccine and dishing out Tamiflu and Relenza as we only have a finite amount stockpiled (not to mention how arduous it is for the pharmaceutical companies to extract the active ingredient, shikimic acid). It seems reckless to be focusing so much on this current pandemic when a more sinister threat is looming.
    Saying that, I wholeheartedly agree that strategies need to change. Tamiflu and Relenza aren’t the magic cure as people seem to think, nor is a vaccine manufactured and mass produced well in a pandemic.

  • gsgs 23 July 2009, 1:19 am

    for years (decades) the wisdom was that influenza survives on hands 5min
    (one old study). But recently (was it this study ?) I saw that it can survive an hour

    In contrast cold is said to survive 3 hours on hands.

    What makes the difference ? The envelope , the spikes ?

    With 5 minute the best strategy could be waiting and not touching anything for 5min
    with the maybe-contaminated-hand rather than washing or alcoholing, which touches things.

  • profvrr 24 July 2009, 10:17 am

    It has always been thought that enveloped viruses are in general less
    stable than non-enveloped. The membrane is highly susceptible to
    disruption by detergents and other chemicals. One of the common cold
    viruses (rhinovirus) is non-enveloped and its longevity on surfaces
    might be related to its structure. However enveloped viruses always
    surprise; for example some can survive passage in the human alimentary

  • cupton 24 July 2009, 11:18 am

    And vaccinia is super stable if freeze-dried… not sure about on a door handle.

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  • Hand Sanitizer Dispenser 11 April 2010, 10:32 am

    Great. I agree with you.

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