Winokur PL, Patel SM, Brady R, Chen WH, El-Kamary SS, Edwards K, Creech CB, Frey S, Keitel WA, Belshe R, Walter E, Bellamy A, Hill H. Safety and Immunogenicity of a Single Low Dose or High Dose of Clade 2 Influenza A(H5N1) Inactivated Vaccine in Adults Previously Primed With Clade 1 Influenza A(H5N1) Vaccine. The Journal of infectious diseases. 2015 Aug 15;212(212). 525-30. PMID: 25712967 [PubMed] PMCID: PMC4598805
Influenza A(H5N1) vaccination strategies that improve the speed of the immunological response and cross-clade protection are desired. We compared the immunogenicity of a single 15-μg or 90-μg dose of A/H5N1/Indonesia/05/05 (clade 2) vaccine in adults who were previously primed with A/H5N1/Vietnam/1203/2004 (clade 1) vaccine. High-dose vaccine resulted in significantly higher titers to both clade 1 and 2 antigens. Clade 2 titers were unaffected by the previous dose of clade 1 vaccine. Low-dose priming with a mismatched pandemic influenza A(H5N1) vaccine would improve the rapidity, magnitude, and cross-reactivity of the immunological response following a single high-dose, unadjuvanted, pandemic vaccine.