STEMMING THE SPREAD: People wear face masks in Mexico City as a precaution against the 2009 swine flu pandemic that began in April of that year.© ELIANA APONTE/REUTERS/CORBIS
Two weeks into 2013, the governor of New York declared a statewide public-health emergency. Only halfway through the flu season, almost 20,000 cases of influenza had already been reported in the state, a fourfold increase over the previous winter. To tackle the epidemic, Governor Andrew Cuomo increased the availability of vaccines and allowed pharmacists to vaccinate people under 18.
As well as protecting individuals, better vaccination coverage can also help curb disease transmission. But there are still many outstanding questions regarding how infections like flu actually spread. Where do most transmissions occur? What dictates an individual’s risk of infection? Which groups should we target with control measures?
For many pathogens, social contacts are an important component of disease transmission. From influenza to SARS, our risk ...
