Influenza vaccines include hemagglutinin from at least one influenza A virus strain and at least one influenza B virus strain. They also include an oil-in-water emulsion adjuvant with submicron oil droplets, comprising squalene. In some embodiments the hemagglutinin concentration is >；12 μg/ml per strain. In some embodiments the squalene concentration is <；19 mg/ml. In some embodiments the vaccine is mercury-free. In some embodiments the vaccine has a unit dose volume between 0.2-0.3 mL. In some embodiments the squalene concentration is 9.75 mg/mL or 4.88 mg/mL. In some embodiments the vaccine includes antigens from two influenza A virus strains and two influenza B virus strains.
