The WHO Hears a Flu & What You Should Do

The WHO Hears a Flu & What You Should Do

Much has been written about the 2009 H1N1 influenza outbreak.  The World Health Organization’s doyenne of viral awareness, Margaret Chan, has amped up global concern.  Although we share in the wisdom of CDC’s preventive actions we resist Macbeth’s “horrible imaginings” and extend their advice to what consumers can do to better protect themselves and their families.

First get vaccinated.  All flu viruses are best transmitted by aerosol or droplet sprays during coughing and sneezing, not so much via physical contact.  Therefore, once exposed to sick persons the emphasis on hand sanitization and hand washing are good practice but short of the mark.  Flu viruses do not survive for long on hard surfaces.  Thus the best practice is to avoid exposure to the sick and once sick to isolate yourself.  Also you should try to suppress coughing and sneezing, and wear masks sufficient to reduce transmission in close quarters.  Installing UV germicidal units in sick rooms may also help.

The current medical evidence from the spring and summer 2009 case reports, gathered from both hemispheres, suggests that the severity and transmission [6-8%] of this 2009 pandemic virus is no more rapid than other flu viruses; the symptoms are mild.  The eruption of this virus is most similar to the reemergence of a new H1N1 virus in 1977 (mild).  In that year H1N1 reemerged after many years of “disappearance” hitting college students in 1977 and downshifting demographics further in 1978, but producing average excess mortality.  Media comparisons to the pandemic of 1957 (H2N2, severe) and 1968 (H3N2, moderate) are overwrought.  Typically new emergent flu viruses “replace” seasonal ones in their first years and become milder over the first four years.  The mildness, drug sensitivity (Tamiflu) and replacement effect of this 2009 H1N1 virus suggest that excess mortality above “normal” flu years will not be excessive although a younger demographic will be hit. Morbidity estimates will be difficult due to reporting biases of all kinds.  Hyperawareness, misdiagnosis, and fear will also contribute to overestimation of incidence and prevalence.

The state of our knowledge of the birth and spread of any influenza virus is surprisingly incomplete.  The most compelling theory, accounting for many unresolved observations, is that proposed by Dr. Hope-Simpson in the 1980’s recently championed by Drs.Cannell and Zasloff.  This theory states that influenza spread is not explained simply by sick-to-well transmission. For example, the secondary spread rate is low (70% of households have one case) and most waves burn out prematurely.  In their model new flu is spread quickly to asymptomatic carriers who are latently contagious thus creating reservoirs of virus, and eventually, clusters of infection (in and out of season).  An environmental factor, decreasing seasonal UV exposure, triggers the re-emergence of active viral transmission as winter deepens.  This is mediated by decreasing Vitamin D levels in the well population.  Vitamin D is a natural facilitator of the “innate” antimicrobial (anti-viral) systems that are independent of “adaptive” immune systems such as those stimulated by vaccines.  These innate systems are found, for example, in skin and mucous membranes.  Individual levels of Vitamin D differ within and between individuals for a variety of reasons thus putting certain individuals at risk of infection, particularly in winter.  As individual defenses wane individuals who may have been protected from an exposure to a virus now become infected.  Proponents of the Hope-Simpson theory claim that doses of 400 – 2,000units/day are effective at decreasing illness incidence.  The combination of vaccination, Vitamin D, sunlight, and virus avoidance seem like a prudent prevention plan.

[Dr. Riker is the former Associate Director, Clinical Development at P&G Consumer Healthcare supporting its products for colds & flu; he is a member of the Infectious Disease Society of America]