New Study Shows Flu Vaccine Reduced Children’s Risk of ICU Flu Admission by Three-Fourths
First study to estimate vaccine effectiveness against flu admissions to pediatric ICUs
Getting an influenza vaccine reduces a child’s risk of flu-related intensive care hospitalization by 74%, according to a study from the Centers for Disease Control and Prevention (CDC), published in the Journal of Infectious Diseases.
The study is the first to estimate vaccine effectiveness (VE) against flu admissions to pediatric intensive care units (PICUs). The CDC recommends annual flu vaccination for everyone 6 months of age and older and especially for children at high risk of serious flu-related complications. The latter group includes children younger than 5 years of age and children of any age with certain chronic medical conditions, such as asthma, diabetes, or developmental delays.
Researchers analyzed the medical records of 216 children aged 6 months through 17 years admitted to 21 PICUs in the U.S. during the 2010–2011 and 2011–2012 flu seasons. They found that flu vaccination reduced a child’s risk of being admitted to a PICU for flu by an estimated 74%. These findings show that while vaccination may not always prevent flu illness, it can protect against more serious outcomes.
Although flu vaccination was associated with a significant reduction in the risk of PICU admission, flu vaccine coverage was relatively low among the children in this study: only 18% of children with the flu admitted to a PICU had been fully vaccinated. Moreover, more than half (55%) of the children had at least one underlying chronic medical condition that placed them at higher risk of serious flu-related complications.
The CDC usually measures flu VE against “medically attended flu illness” — that is, how well it protects against having to visit the doctor for flu symptoms. During the 2010–2011 and 2011–2012 flu seasons, the midpoint VE estimates against medically attended illness were 60% and 47%, respectively.
“Because some people who get vaccinated may still get sick, it’s important to remember to use our second line of defense against flu: antiviral drugs to treat flu illness,” said Dr. Alicia Fry, a medical officer in the CDC’s Influenza Division. “People at high risk of complications should seek treatment if they get a flu-like illness. Their doctors may prescribe antiviral drugs if it looks like they have influenza.”
Flu causes hospitalizations in children each season, but the number of children affected can vary, depending on the severity of the season. The CDC estimates that 20,000 children younger than 5 years of age are hospitalized on average each year. For children younger than 18 years of age, published studies suggest an annual range of flu-related hospitalization rates of between one and seven children per 10,000 children. Between 4% and 24% of hospitalized children require PICU admission.
Source: CDC; March 27, 2014.