Two new, higher-strength versions of flu vaccines will be offered this season for adults ages 65 years and older, according to the Centers for Disease Control and Prevention. 

New quadrivalent formulations of high-dose and adjuvanted influenza vaccines are in production for older adults. Fluzone High-Dose Quadrivalent (HD-IIV4) is intended to replace the trivalent formulation of Fluzone High-Dose (HD-IIV3). In contrast, the new Fluad Quadrivalent (aIIV4) also will be made available. Fluad Quadrivalent contains an adjuvant intended to strengthen the immune response.