A Cell Culture (Vero)–Derived H5N1 Whole-Virus Vaccine Induces Cross-Reactive Memory Responses

Novel strategies are required to provide rapid vaccine coverage in the event of an influenza pandemic. A phase I/II dose finding/ formulation study was performed with a whole-virus H5N1 clade 1 A/Vietnam vaccine (2-dose priming regimen) to eval-uate safety and immunogenicity. Seventy-seven of 141 subjects in this study received a booster (12–17 months after priming) with a 7.5-mg dose of a clade 2.1 A/Indonesia vaccine. The prime-boost regimen resulted in antibody responses against clade 1, 2.1, 2.2, and 2.3 viruses that were significantly higher than those after the priming regimen. These findings demon-strate that a prime-boost regimen may alleviate vaccine supply constraints in a pandemic. Clinical trials registration. NCT00530660. Highly pathogenic strains of A/Influenza H5N1 virus continue to cause outbreaks in fowl and also result in human disease with a high fatality rate [1]. Preexposure vaccination with an appropriate vaccine is considered to protect against pandemi