Thursday, July 20, 2006

Hand Hygiene: The Boring Way to Save a Few Hundred Thousand Lives (or More)

Donald Goldman, M.D. began his article in the New England Journal of Medicine with the true story:

"A new mother sits by her tiny, premature baby in a neonatal intensive care unit. She watches as a physician touches the baby without first washing his hands or using the waterless, alcohol-based hand antiseptic just a couple of feet away. A few minutes later, a nurse and then another doctor also fail to perform these basic procedures. When her baby was admitted to the unit, the mother was told to remind caregivers to wash their hands, but only after witnessing repeated failures does she muster the courage to speak up about the practice she thought would be routine. By then, her baby has acquired methicillin-resistant Staphylococcus aureus (MRSA) probably transported on the hands of a caregiver who had been examining other babies who are colonized with MRSA. A few days later, MRSA invades the baby's bloodstream; it eventually proves fatal. Such preventable infections, caused by the failure to practice hand hygiene, are far from rare, and they occur in many of the finest neonatal intensive care units in the United States."

Beyond Neonatal Care

The challenge of this blog is not to improve neonatal care, but to think through the likelihoods, possible evolutions, and ultimate denouement of an H5N1 pandemic. Still, there are implications of Goldman's report that are directly relevant:
  1. Even among experts and even in highly aware environments, there are repeated incidents of faulty hand hygiene that cost lives.
  2. Given this and given a pandemic influenza, how many lives might be saved by improving the hand hygeine of the "average Joe"?
A Measure of the Benefits

There are only a few things that one can do to increase the probability of living to see the other side of a HPAI pandemic:
  1. Social distancing --- the more the better. Self-quarantine is best.
  2. Hand hygiene
  3. Use of N95 (or better) masks when exposed to outsiders
  4. Appropriate use of antiviral drugs, such as Tamiflu or Relenza
Each of these measures is capable of cutting your mortality risk by a substantial factor. Naturally, the sizes of these factors are subject to debate, and the realized values will depend on the features of the pandemic.

Anyone can place a bet. If I were to put my money on the values for the discount factors, I would suggest:
  1. Social distancing is HUGE. It should at least buy you a factor of 3 and might buy you a factor of 10 depending on the nature of the pandemic and how well you can genuinely isolate yourself.
  2. Hand hygiene is likely to buy you a factor of 3 to 5. If you cannot achieve serious social distancing, this is a very important factor.
  3. Masks are useful, but even if appropriately used they may only buy you a factor of 2. Most likely, they will buy you less.
  4. Finally, antivirals have been observed to cut serious side effects of 'regular' flu by a factor of 5 or so. Many people expect this ratio to hold up in the case of H5N1. Governments around the globe are making serious bets that this factor, or a larger one, will apply.
Bottom Line

People who can effectively execute all of these defenses will probably be able to cut their risk by a factor of 120 to 400. In the commonly assumed 'worse case' model with 2% US fatality rate, this would cut your probabilities to perhaps about one chance in 10,000.

This is a risk one can live with.

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Many Thanks to Dean Foster who provided the reference that motivated this note.

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