In late December, the raw measles numbers coming out of South Carolina looked like an outbreak that was winding down. A CDC model told state officials the opposite, and the state kept its response staffed through the holidays. Two weeks later, the cumulative number of confirmed cases had more than doubled.
That sequence is the substance of a new CDC report published this week, and it describes the first time the agency has run this kind of real-time modeling during an active measles outbreak. The technique is called nowcasting, and it exists to answer a question every health department faces during a fast-moving outbreak: are today's numbers real, or just incomplete?
