A research paper published last year aimed to address 9 puzzling things about influenza:
- Why is influenza seasonal and ubiquitous, where does the virus hide between epidemics?
- Why are the epidemics so fast to spread?
- Why do they end so quickly?
- Why do countries on similar latitudes have coincidental epidemics?
- Why is the serial interval obscure?
- Why is the secondary attack rate so low?
- Why did earlier epidemics spread rapidly without modern transport?
- Why does experimental inoculation of seronegative humans fail to cause illness in tests?
- 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.
Cannell, 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