An inactivated quadrivalent influenza vaccine (QIV) was shown to have a higher efficacy in the prevention of moderate-to-severe disease in children aged 3 to 8 years than against influenza of any severity, according to a phase 3 study reported in the New England Journal of Medicine.
More than 5,000 children were enrolled in the clinical trial for GlaxoSmithKline’s FluLaval Quadrivalent from 15 centers located in Bangladesh, the Dominican Republic, Honduras, Lebanon, Panama, the Philippines, Thailand, and Turkey. Approximately half of the children received the QIV 15-mL dose, containing A/California/7/2009 (H1N1), A/Victoria/210/2009 (H3N2), B/Brisbane/60/2008 (Victoria), and B/Florida/4/2006 (Yamagata). The rest received hepatitis A vaccine (Havrix). The primary end point of the study was the confirmation of influenza A or B of any severity, which was confirmed by reverse-transcriptase-PCR assay. Secondary end points were confirmed moderate-to-severe influenza A or B and culture-confirmed influenza A or B.
Children with moderate-to-severe influenza had a temperature of 39°C or higher, acute otitis media, lower respiratory tract illness, or serious extrapulmonary complications.
Varsha K. Jain, MD, and colleagues reported that the efficacy in the QIV group of almost 2,400 children with a mean age of 5.4 years was 55.4%. Among children with moderate-to-severe influenza, the efficacy in the QIV group was 73.1%.
“In an exploratory analysis, we assessed QIV efficacy to influenza A subtype and influenza B lineage. The QIV was most effective against moderate-to-severe influenza A. Only two cases of influenza B caused by Yamagata lineage viruses was observed, both in the control group,” Jain noted.
The efficacy against influenza of any severity seemed to be lower in the children aged 3 to 4 years (35.3%) whereas its efficacy was much higher in the children aged 5 to 8 years (67.7%).
Other findings included an 80% reduction in the rate of lower respiratory tract illness and a 70% reduction in the rate of body temperature above 39°C in the QIV group, the authors noted.
“Among children with moderate-to-severe disease, the QIV, as compared with the control vaccine, was associated with 69% fewer medical visits, 75% fewer hospitalizations, 77% fewer absences from school, and 61% fewer parental absences from work,” Jain said.
The study was funded by GlaxoSmithKline Biologicals. The vaccines were manufactured by GlaxoSmithKline Vaccines.