What is R naught (R 0)
How many people the average infected person infects is called the basic reproductive number, or R0 (pronounced "R naught").
Measles, which is probably mankind's most contagious infection, has an R0 of about 18.
Polio's number is about 6;
severe acute respiratory syndrome (SARS) about 5.
For seasonal flu strains, the R0 is about 1.2, and for pandemic strains it is rarely higher than 2. For the novel H1N1 strain, it's about 1.6. What this low R0 means is that flu outbreaks are always teetering on the verge of having their myriad chains of transmission broken by people who get infected but don't pass the virus to anyone else.
http://seekingalpha.com/instablog/283977-focalpoint-analytics/3262855-swine-flu-mers-ebola-and-medical-news-concentrator-september-14-2014-to
