Mathematical modeling.

Efficacy of Treatment only (“T”) vs Treatment and Prophylaxis (“T&P”) strategies for preventing transmission of influenza, assuming a latent period of 1 day and a serial interval of 2.5 days. Efficacy is expressed as the percentage of secondary cases prevented by the intervention.“Fraction with prior immunity” is necessarily lower than fraction vaccinated, as the vaccine is not 100% effective and non-vaccine strains may be responsible for outbreaks. In our modeling, as 45% of ACF C residents were infected, our data can only be used to model up to 55% assumed fraction with prior immunity.