Lower influenza vaccine effectiveness in adults 65+ is driven largely by 2 factors:

Weakened Immune System

Adults 65+ experience age-related decline of the immune system and thus may be less able to mount a sufficient immune response to vaccination, leaving them more vulnerable to influenza infection and its complications.2

Strain Mismatch

This occurs when circulating influenza strains do not match the WHO-selected strains contained in the vaccine. Most often, it is due to mutations from antigenic drift or egg adaptation. It can also occur when the prevalent circulating influenza strains are different from WHO predictions.3,4

WHO=World Health Organization

Adding MF59® Adjuvant to an influenza vaccine is designed to strengthen, broaden, and lengthen the duration of the immune response6-8

This is a conceptualization of the mechanism of action (MOA) of an MF59® adjuvanted influenza vaccine and a standard-dose, non-adjuvanted influenza vaccine.

MF59® Adjuvanted influenza vaccine6-8
Flu vaccine antigen and MF59®
Antigen + MF59® Adjuvant
Flu vaccine adjuvant technology strengthens immune response
Strengthens the immune response by stimulating more immune cells to create more antibodies
Flu vaccine adjuvant technology broadens immune response
Broadens the immune response by creating more diverse, cross-reactive antibodies. This may be important if there is a mismatch between the influenza virus strains in the vaccine and the circulating influenza strains
Non-adjuvanted, standard-dose influenza vaccine6-8
Flu vaccine with antigen only
Antigen only
Flu vaccine with only antigen stimulates immune cells
Stimulates immune cells
Flu vaccine without adjuvant creates fewer antibodies
Creates fewer antibodies

An adjuvanted vaccine for seasonal influenza prevention

Adding an adjuvant can make a difference for those patients 65 years and older.1

Learn more about our adjuvanted influenza vaccineNext screen
Watch how our MF59® Adjuvant works
flu virus cells outline

What's the impact of influenza on adults 65 years and older?

Influenza vaccine effectiveness continues to be challenging as influenza disproportionately affects adults 65 years and older.1

Learn more about the burden of influenzaNext screen

Featured Resources




Educate patients about vaccination with FLUAD QUADRIVALENT (Influenza Vaccine, Adjuvanted).

FLUAD QUADRIVALENT Informational Flashcard


FLUAD® QUADRIVALENT HCP to Patient Discussion Guide

Provides useful information to help address frequently asked questions from patients regarding FLUAD QUADRIVALENT (Influenza Vaccine, Adjuvanted).

FLUAD QUADRIVALENT Coding and Billing Guide


FLUAD® QUADRIVALENT Coding and Billing Guide

Quick reference guide for coding and billing information specific to FLUAD QUADRIVALENT (Influenza Vaccine, Adjuvanted).

Explore the CSL Seqirus Vaccine Portfolio

Please see Important Safety Information and full US Prescribing Information on each vaccine's respective product page.

References.1. Centers for Disease Control and Prevention. Flu & people 65 years and older. Accessed February 12, 2021. https://www.cdc.gov/flu/highrisk/65over.htm 2. Monto AS, Ansaldi F, Aspinall R, et al. Influenza control in the 21st century: optimizing protection of older adults. Vaccine. 2009 27(37):5043-5053. doi:10.1016/j.vaccine.2009.06.032 3. Paules CI, Sullivan SG, Subbarao K, Fauci AS. Chasing seasonal influenza - the need for a universal influenza vaccine. N Engl J Med. 2018 378(1):7-9. doi:10.1056/NEJMp1714916 4. Zost SJ, Parkhouse K, Gumina ME, et al. Contemporary H3N2 influenza viruses have a glycosylation site that alters binding of antibodies elicited by egg-adapted vaccine strains. Proc Natl Acad Sci USA. 2017 114(47):12578-12583. doi:10.1073/pnas.1712377114 5. Garç on N, Leroux-Roels G, Cheng WF. Vaccine adjuvants. Understanding modern vaccines: Perspectives in vaccinology. 2011 1(1):89-113. 6. O'Hagan DT, Ott GS, De Gregorio E, Seubert A. The mechanism of action of MF59—an innately attractive adjuvant formulation. Vaccine. 2012 30(29):4341-4348. doi:10.1016/j.vaccine.2011.09.061 7. O'Hagan DT, Ott GS, Nest GV, Rappuoli R, Del Giudice G. The history of MF59® adjuvant: a phoenix that arose from the ashes. Expert Rev Vaccines. 2013 12(1):13-30. doi:10.1586/erv.12.140 8. Banzhoff A, Pellegrini M, Del Giudice G, Fragapane E, Groth N, Podda A. MF59-adjuvanted vaccines for seasonal and pandemic influenza prophylaxis. Influenza Other Respir Viruses. 2008 2(6):243-249. doi:10.1111/j.1750-2659.2008.00059.x