ATLANTA — Children aged 6 months to 9 years of age who did not receive two doses of vaccine the first time they were immunized against influenza should receive two doses the following season, the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices recommended at its winter meeting.
That was the only major change made to the ACIP's annual influenza statement, approved by the committee at the meeting. No new age or risk groups recommended for routine immunization were added this time around.
For an adequate immune response, children aged 6 months through 9 years receiving influenza vaccine for the first time are supposed to receive two doses given at least a month apart. But, in situations where a child only receives one dose, two studies published in 2006 suggest that protection against influenza is greater with two doses the following year, Dr. Anthony Fiore of the CDC's National Center for Immunization and Respiratory Diseases told the committee.
In one study, when the influenza B antigen was changed for the second season, children who only received one dose in their first season of being vaccinated and one dose in their second season had decreased immunologic response to the influenza B antigen compared with children who received two doses (Pediatrics 2006;118:e579–85).
The other study showed that, in consecutive seasons when the influenza vaccine antigens were unchanged, effectiveness against influenzalike illness in the second season was significantly less for 6− to 21-month-old children being vaccinated for the first time who received one dose in both seasons, compared with 6− to 21-month-olds who received one dose in their first season and two doses in their second season (J. Pediatr. 2006;149:755–62).
The new ACIP recommendation brings it in line with the American Academy of Pediatrics, which issued the same guideline in October 2006.
The American Academy of Family Physicians, which usually follows ACIP's recommendations, will likely change its advice as well, AAFP coliaison Dr. Doug Campos-Outcalt said in an interview.
Although no other major changes were made to the 2007 influenza statement, it will contain some new language. More direct wording will address the lack of scientifically conclusive evidence demonstrating harm from exposure to thimerosal preservative-containing vaccine, and the recommendation that any age- and risk factor-appropriate preparation is acceptable depending on availability. Prior to its vote on the influenza immunization statement, the ACIP heard a presentation by Dr. Jay M. Lieberman summarizing available data on thimerosal (see accompanying story).
Reinforcement of the need for health care workers to be immunized against influenza will be included in the statement, which also will mention new recommendations from several professional societies that all facilities employing health care workers offer the vaccine and require a written declination for those who chose not to be vaccinated.
New language on the timing of influenza immunization will note that although the ideal time is late September and October, immunization efforts should continue through January and beyond. Peak influenza activity occurs in February or March in most seasons, Dr. Fiore said.
Physicians who treat children should be aware that the ACIP is gearing up to expand its influenza vaccination recommendations beyond the current ages 6 months to 5 years to include all children aged 5–18 years. A meeting is planned for this summer to consider the scientific and implementation issues, with the goal of implementation for the 2008–2009 flu season, Dr. Ban Mishu Allos, the ACIP's influenza immunization task force chair, said.
Indeed, universal annual childhood immunization against influenza is already a stated goal of several national, state, and regional professional health care organizations, including the American College of Obstetricians and Gynecologists, the American Osteopathic Association, the Society for Adolescent Medicine, The National Medical Association, and the Society of Teachers of Family Medicine, Dr. Deborah Wexler, chief of the Immunization Action Coalition, informed the committee at the meeting.