Even though spring is here, flu activity remains elevated in parts of the country; the flu season and new cases will continue into May, according to the U.S. Centers for Disease Control (CDC). In fact, sporadic activity may continue for some time, especially in places where activity started later.
Highlighting the importance of vaccination, a new CDC study, published in the Journal of Infectious Diseases, finds that the flu vaccine reduced children’s risk of ICU hospitalization by 74 percent.
Protecting Kids from Serious Complications
The CDC study, which is the first to measure vaccine effectiveness against flu admissions to pediatric intensive care units (PICUs), demonstrates the vaccine's effectiveness in protecting children from developing more serious flu outcomes.
A total of 75 influenza-associated pediatric deaths have been reported during the 2013-2014 season, according to FluView, the CDC’s weekly influenza surveillance report. The CDC recommend annual flu vaccination for everyone six months old and older, especially for children at high risk of serious flu-related complications. Children younger than five and children of any age with certain chronic medical conditions like asthma, diabetes, or developmental delays are at higher risk of serious flu complications.
The CDC study evaluated the medical records of 216 children, ages six months through 17 years, who were admitted to 21 PICUs in the U.S. during the 2010–2011 and 2011–2012 flu seasons. They discovered that flu vaccination reduced a child's risk of winding up in the pediatric intensive care unit for flu by an estimated 74 percent. These findings are significant because although vaccination may not always prevent the flu, it can protect against more serious outcomes.
Pointing out that although flu vaccination was associated with a significant reduction in risk of PICU admission, flu vaccine coverage was relatively low among the children in this study: only 18 percent of flu cases admitted to the ICU had been fully vaccinated.
More than 55 percent of cases involved at least one underlying chronic medical condition that put them at higher risk of serious flu-related complications.
Watching Out for the Flu
Fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills, and sometimes diarrhea and vomiting are all symptoms of the flu. The CDC estimates that 20,000 children younger than five years of age are hospitalized on average each year. For children younger than 18 years, published studies report that per 10,000 children, there is an annual range of flu-related hospitalization rates between one and seven children. Between 4 percent and 24 percent of hospitalized children are admitted to PICUs.
In a press statement, Dr. Alicia Fry, a medical officer in the CDC’s Influenza Division, said that the study results underscore the importance of an annual flu vaccination, which can keep children from being admitted to ICUs. “It is extremely important that all children—especially children at high risk of flu complications—are protected from what can be a life-threatening illness," she said.
CDC usually measures flu vaccine effectiveness (VE) against medically attended flu illness, or how well it protects against having to go to the doctor for flu symptoms. During the 2010-2011 and 2011-2012 seasons, the midpoint VE estimates against medically attended illness were 60 percent and 47 percent respectively.
Antiviral Drugs: A Second Line of Defense
Emphasizing that because some people who get vaccinated may still get sick, Fry said that a second line of defense against the flu—antiviral drugs to treat flu illness—are recommended, and that people at high risk of complications should seek treatment if they get a flu-like illness.
In a separate study, published in the Journal of Infectious Diseases, lead author Dr. Richard Whitley of the University of Alabama at Birmingham pointed out that, at the time of the study, immunization of older children had not yet become a priority of the U.S. Public Health Service. The researchers said, “As a consequence, the importance of antiviral agents, particularly neuraminidase (NA) inhibitors, cannot be overemphasized. From an epidemiological perspective, influenza resulted in higher childhood mortality than did Bordetella pertussisinfection in 2003–2004. During that season, 153 children died of influenza, and two‐thirds were [younger than] 5 years of age. Importantly, nearly 50 percent of these children were previously healthy, with no underlying illness.”