9 Influenza Puzzles

A research paper published last year aimed to address 9 puzzling things about influenza:

  1. Why is influenza seasonal and ubiquitous, where does the virus hide between epidemics?
  2. Why are the epidemics so fast to spread?
  3. Why do they end so quickly?
  4. Why do countries on similar latitudes have coincidental epidemics?
  5. Why is the serial interval obscure?
  6. Why is the secondary attack rate so low?
  7. Why did earlier epidemics spread rapidly without modern transport?
  8. Why does experimental inoculation of seronegative humans fail to cause illness in tests?
  9. Why do seniors die of flu despite vaccination?

The answer could be chemical – vitamin D.

The researchers cited below suggest that:

Two factors explain the nine conundrums: vitamin D’s seasonal and population effects on innate immunity, and the presence of a sub-population of “good infectors.” If true, their revision of Edgar Hope-Simpson’s theory has profound implications for the prevention of influenza.

Research Blogging IconCannell, J., Zasloff, M., Garland, C., Scragg, R., & Giovannucci, E. (2008). On the epidemiology of influenza Virology Journal, 5 (1) DOI: 10.1186/1743-422X-5-29