Background: Recombinant baculovirus-expressed hemagglutinin (rHA [FluBlok]) influenza vaccine is unique in avoiding production in eggs and its rapid production capability.
Objective: Compare the safety and immunogenicity of trivalent FluBlok to egg-grown trivalent influenza vaccine (TIV) in children.
Methods: Healthy children were randomized to receive two doses of study vaccines. TIV (7.5 microg HA/antigen), FluBlok-22.5 (22.5 microg rHA/antigen), or FluBlok-45 (45 microg rHA/antigen) were given to 115 children ages 6-35 months. TIV (15 microg HA/antigen) or FluBlok-45 was given to 41 children ages 36-59 months. Safety and reactogenicity data were collected post-vaccination. Serum hemagglutination-inhibition antibody (HI) titers were measured before and 28 days after vaccination.
Results: No serious vaccine-related adverse events occurred and reactogenicity events to equal volumes of TIV or FluBlok were generally similar. However, in the younger children, selected local and systemic symptoms were recorded significantly more frequently to 0.5 mL FluBlok-45 than to 0.25 mL doses of either the FluBlok-22.5 or 7.5 microg TIV vaccines. In the younger children, the immunogenicity to TIV was generally significantly superior to FluBlok. Serologic responses to FluBlok were higher in the older children than the younger group, but were still somewhat lower compared to TIV.
Conclusion: These data suggests that FluBlok is as safe but less immunogenic than similar volumes of TIV, particularly in the youngest children. The immunogenicity data is the converse of what has been observed in adults. Further studies examining the immunogenicity of FluBlok in older children are warranted.