Thanks to the closure of US schools for the holiday season, influenza transmission is reduced and the trajectory of seasonal influenza epidemics is delayed, according to Georgetown researchers.

“In comparing the effects of two purported mechanisms driving holiday dynamics — school closure and increased travel — we were surprised to find that changes due to school closure explained nearly all of the delay in peak timing and increase in spatial synchrony in our model,” researchers wrote in the Journal of Infectious Diseases.

In eight influenza seasons from from October 2001 to May 2009, Bansal and colleagues observed a temporary reduction in influenza activity during the weeks following Christmas. Transmission decreased by approximately 15% in most seasons, falling below the epidemic threshold after Christmas, then rebounding to epidemic levels within a few weeks. Seasonal peaks occurred an average of 5 weeks after the holidays.