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Pediatric trials needed for pandemic influenza vaccine
Health officials emphasize importance of establishing safety profiles.
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The feasibility of extrapolating pediatric dose and scheduling recommendations from adult data, safety concerns regarding the need for larger doses and novel adjuvants and establishing high-risk pediatric subpopulations were among topics discussed regarding pandemic influenza vaccine development at the FDA’s Vaccines and Related Biological Products Advisory Committee meeting held in Washington recently.
“At some point, an influenza pandemic is going to occur. We don’t have information about what form it will take, when it will come or what virus will be the perpetrator,” committee member Robert S. Daum, MD, professor of pediatrics at the University of Chicago Medical Center, said at the meeting. “I’m a strong proponent that children should be included in influenza preparedness planning.”
Data from previous trials involving H5N1 influenza vaccine in adults have indicated that multiple inoculations and larger doses of antigen were necessary to achieve acceptable antibody titers compared with seasonal vaccine. Additionally, several vaccine candidates incorporate novel adjuvants, prompting concerns about possible autoimmune responses in young children and safety issues that may arise in response to larger doses of antigen.
Committee members agreed that trials evaluating vaccine safety and immunogenicity are needed for pediatric subpopulations with a higher than normal risk for hospitalization due to influenza, including children aged younger than 6 months; those with nephritic syndrome or antibody deficiency syndrome and children living in areas where avian influenza is endemic.
“When we took this issue to the public, it was clear that an important value is protecting children. We really need to know this information, but we need to do it methodically and comprehensively,” said committee member Bruce Gellin, MD, MPH, director of the National Vaccine Program Office.
Various pediatric trials evaluating vaccines against influenza strains with pandemic potential have been conducted or are ongoing at multiple European sites, Thailand and Australia, but no U.S. trials have received FDA approval. Influenza A H5N1 is currently the focus of pandemic preparedness, but avian strains have the potential to change seasonally like human influenza viruses. The committee recognized that influenza A subtypes H2, H7 and H9 have pandemic potential and should also be studied. – by Nicole Blazek
The need for ongoing research in new influenza vaccines is important, and research involving vaccines against pandemic influenza strains in children is also important. Currently, we do not have either a vaccine or antiviral therapy available for infants aged younger than 6 months, the group at highest risk for hospitalization. All children are at risk for contracting influenza, and all are at risk to become infected during annual epidemics or when the next pandemic occurs. Thus, the need to include children in influenza vaccine research programs is critical. This needs to be emphasized as exciting new adjuvants and vaccine candidates are becoming available that may ultimately increase vaccine effectiveness.
– Janet Englund, MD
Seattle Children’s Hospital, University of Washington
ACIP Member