Between patients last week the skeptical cardiologist skipped over to the employee health office at St. Luke’s and requested he be given a flu shot.
To my surprise, I was given a choice between a “high dose” flu shot which was “recommended for individuals 65 and older” and the regular quadrivalent flu vaccine.
I hadn’t been aware of this “high dose” flu shot previously thus had not had a chance to research it. My time was limited and I decided to go with the high dose flu vaccine hoping that high dose did not also mean more chance for side effects.
Fortunately, I had no side effects and thus far have not contracted the flu.
Influenza More Deadly In Elderly But Vaccine Less Effective
Influenza, of course, is a huge killer which causes around 36,000 deaths per year in the United States. We adults 65 and older particularly vulnerable to complications of influenza and we are the ones that account for most of the more than 200,000 hospitalizations per year from the disease.
Hospital cardiology consultations typically spike during flu season as a bad case can worsen heart failure or trigger heart attacks and arrhythmias.
Although vaccination is the most effective intervention against influenza and associated complications, older individuals mount a lower antibody response to the vaccine compared to younger individuals.
Fluzone HD: High Dose Antigen Which Increases Antibody Reponse
To improve protect strategies to improve antibody responses to influenza vaccine in the older population, such as increasing the amount of antigen in the vaccine have been developed.
The vaccine I received is called Fluzone HD and is manufactured by the French pharmaceutical company Sanofi. It is a high-dose, trivalent, inactivated influenza vaccine (IIV3-HD) and contains four times as much hemagglutinin (HA) as is contained in standard-dose vaccines.
AFter studies demonstrating an acceptable safety profile and superior immunogenicity as compared with a standard-dose vaccine, IIV3-HD was licensed for use in the United States in December 2009,
Studies Show Improved Relative Efficacy Of Fluzone Compared to Standard Dose Flu Vaccine
A study published NEJM in 2014 proved the clinical superiority of Fluzone. It has a relative efficacy compared to standard vaccines of around 24%.
The CDC summarizes it as follows
Fluzone High-Dose (HD-IIV3) met prespecified criteria for superior efficacy against laboratory-confirmed influenza to that of SD-IIV3 in a randomized trial conducted over two seasons among 31,989 persons aged ≥65 years, and might provide better protection than SD-IIV3 for this age group . For the primary outcome (prevention of laboratory-confirmed influenza caused by any viral type or subtype and associated with protocol-defined ILI), relative efficacy of HD-IIV3 compared with SD-IIV3 was 24.2% (95% CI = 9.7–36.5%).
Subsequent studies have provided further support for the improved efficacy of Fluzone according to the CDC:
These findings are further supported by results from retrospective studies of Centers for Medicare and Medicaid Services (CMS) and Veterans Administration data, as well as a cluster-randomized trial of HD-IIV3 versus SD-IIV among older adults in nursing homes A meta-analysis reported that HD-IIV3 provided better protection than SD-IIV3 against ILI (relative VE = 19.5%; 95% CI = 8.6–29.0%); all-cause hospitalizations (relative VE = 9.1%; 95% CI = 2.4–15.3); and hospitalizations due to influenza (relative VE = 17.8%; 95% CI = 8.1–26.5), pneumonia (relative VE = 24.3%; 95% CI = 13.9–33.4), and cardiorespiratory events (relative VE = 18.2%; 95% CI = 6.8–28.1)
Should You Choose Fluzone?
Most likely, now that I have had a chance to look in detail at the studies supporting Fluzone HD for the elderly and review the CDC recommendations, I would choose it for myself for vaccination this year.
This is not a slam dunk decision and the CDC is actually quite wishy washy in its recommendations basically saying any formulation of vaccine is OK with them
For persons aged ≥65 years, any age-appropriate IIV formulation (standard-dose or high-dose, trivalent or quadrivalent, unadjuvanted or adjuvanted) or RIV4 are acceptable options.
As the CDC points out, we need more studies comparing these different flu vaccines to help guide decision-making.
Addendum. Dr. Chelsea Pearson, the prominent St. Louis internist,tells me she recommends Fluzone or Flublok to her patients 65 or older.
Flublok is a quadrivalent recombinant vaccine of standard dosage.
A head to head comparison of these two vaccines would be nice to help patients and physicians decide which to take.
Cost was not an issue in my decision but a year ago Canadian health officials felt the five-fold greater cost of flu zone HD was not warranted (see here.)
N.B. Be aware there is a quadrivalent flu vaccine from Sanofi also called fluzone. From the FDA:
Tradename: Fluzone, Fluzone High-Dose and Fluzone Intradermal
Manufacturer: Sanofi Pasteur, Inc (for Fluzone High-Dose and Fluzone Intradermal only)
- Fluzone is indicated for active immunization of persons 6 months of age and older against influenza disease caused by influenza virus subtypes A and type B contained in the vaccine.
- Fluzone High-Dose is indicated for active immunization of persons 65 years of age and older against influenza disease caused by influenza virus subtypes A and type B contained in the vaccine.
- Fluzone Intradermal indicated for active immunization for use in adults 18 through 64 years of age against influenza disease caused by influenza virus subtypes A and type B contained in the vaccine.