According to the Centers for Disease Control and Prevention (CDC) influenza activity continues to increase in the United States and most of the nation is now experiencing high levels of influenza-like-illness (ILI). The CDC also notes that some people, such as older people, people with certain health conditions, and young children are at high risk for serious flu complications. According to the latest FluView report from the CDC, the agency’s current position is that people who have not yet been vaccinated this season should be vaccinated as soon as possible. In view of the increased risk of complications among young children, a new study evaluated whether young children were being vaccinated for influenza. Researchers affiliated with several East Coast Medical Centers and the CDC published their findings on January 6 in the journal Pediatrics.
The study authors conducted a study to characterize the healthcare burden of influenza from 2004 through 2009, years when influenza vaccine recommendations were expanded to all children aged six months of age or older. They reviewed laboratory-confirmed cases of influenza children less than five years of age who presented with fever and/or acute respiratory illness to inpatient and outpatient settings during five influenza seasons in three US counties. Enrolled children had nasal/throat swabs tested for influenza by reverse transcriptase-polymerase chain reaction and their medical records reviewed. Rates of influenza hospitalizations per 1,000 population and proportions of outpatients (emergency department and clinic) with influenza were computed.
The study population comprised 2,970 children who were hospital inpatients, 2,698 children who visited an emergency department, and 2,920 children who visited a medical clinic. The single-season influenza hospitalization rates were 0.4 to 1.0 per 1,000 children aged five years or less and highest for infants less than six month of age. The proportion of outpatient children with influenza ranged from 10-25% annually. Among children hospitalized with influenza, 58% had physician-ordered influenza testing, 35% had a discharge diagnosis of influenza, and 2% received antiviral medication. Among outpatients with influenza, 7% were tested for influenza, 7% were diagnosed with influenza, and less than 1% had antiviral treatment. Throughout the five study seasons, less than 45% of influenza-negative children six months of age or younger were fully vaccinated against influenza.
The authors concluded that despite expanded vaccination recommendations, many children are insufficiently vaccinated, and substantial influenza burden remains. Antiviral use was low. They recommended that future studies are needed to evaluate trends in use of vaccine and antiviral agents and their impact on disease burden and identify strategies to prevent influenza in young infants.
For the fourth consecutive week, the proportion of individuals seeing their healthcare provider for influenza-like illness is above the national baseline; it has risen sharply from 2.8% to 5.6% over the past 4 weeks. A total of 29 states and New York City are now reporting high flu activity. Last week, 16 states reported high flu activity; in addition, nine states reported moderate levels of flu activity. States reporting high flu activity for the week ending December 29 include Alabama, Arkansas, Colorado, Florida, Georgia, Illinois, Indiana, Kansas, Louisiana, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, and Wyoming. According to the CDC, it is likely that the increased flu activity will continue for a while. Based on the last 10 flu seasons, influenza-like illness remained at or above baseline for about 12 weeks––and up to 16 weeks during the 2005-2006 season.