Any parent knows that when a preschooler gets the flu, it won't be long before the rest of the family is bedridden too. Three- and 4-year-olds are infamous for their runny noses and spewing coughs, not to mention their indifference to tissues and hand-washing.
Now, however, experts think this beloved age group is doing more than infecting their families. A new study suggests that 3- and 4-year-olds may be powerful drivers of annual influenza outbreaks.
The findings could lead to changes in the nation's strategy on flu vaccination.
The study, from Children's Hospital Boston, showed that preschool-age children are the first to show up each year in emergency rooms and clinics with flu, a pattern that typically begins in late September. Babies younger than 2 tend to arrive with symptoms a week or two later, while older children begin to arrive in October. Adults don't generally show up until November.
Moreover, preschoolers may foreshadow the severity of any given influenza season. As the number of babies and preschoolers with the flu increased in the study, so too did flu-related deaths in the elderly.
Preschoolers are thought to be robust flu-spreaders because of their poor hygiene, close contact with other children and because they shed the virus -- remain infectious -- longer than other age groups.
"It's well known that preschoolers introduce flu into households. But what was not previously described is that children are leading off the epidemic," says Dr. Kenneth Mandl, an attending emergency room physician at Children's Hospital Boston and coauthor of the study. "Not only do preschoolers come in first, they can be used as sentinels, giving a three-week window into the future. That's a very important surveillance and early warning function."
The study, published in the Oct. 1 issue of the American Journal of Epidemiology, used a computerized biosurveillance system to collect data from five healthcare settings in the Boston area from 2000 through 2004.
The findings are expected to rekindle interest among public health officials in expanding flu vaccine recommendations to 3- and 4-year-olds. Under the current plan, the government recommends flu vaccine for people at high risk for developing complications or dying, such as the elderly, infants and chronically ill individuals.
Last year, the CDC began recommending vaccines for babies ages 6 to 23 months because studies show children younger than 2 have hospitalization rates second only to people age 65 and older.
