Chang LJ, et al. - Given that for adults ≥ 65 years of age, a high-dose, split-virion inactivated trivalent influenza vaccine (IIV3-HD; Fluzone High-Dose, Sanofi Pasteur) is available. Researchers conducted a randomized, modified double-blind, active-controlled, multi-center trial in healthy adults ≥ 65 years of age investigating the safety and immunogenicity of a quadrivalent high-dose split-virion inactivated influenza vaccine (IIV4-HD). They randomized 2,670 adults in a 4:1:1 ratio to receive a single intramuscular injection of IIV4-HD, the licensed high-dose, split-virion inactivated trivalent influenza vaccine (IIV3-HD), or an IIV3-HD containing the alternate B-lineage strain. Outcomes suggested that the addition of a second B strain in IIV4-HD results in the achievement of enhanced immunogenicity against the added strain without jeopardizing the immunogenicity of the other strains or the vaccine’s tolerability.