Stop the Flu: Fluzone High-Dose A Better Choice for the Elderly?

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Fluzone comes in two doses, the standard and the high-dose for the elderly. Image by the CDC.

Fluzone comes in two doses, the standard and the high-dose for the elderly. Image by the CDC.

What lessons have pharmaceutical companies learned from last year’s epidemic flu season?

The 2012-2013 started about four weeks early and was considered by public health professionals as an “intense season.”

Boston declared a public health emergency because the influenza virus had spread to so many people in the city, and other cities set up tents outside of hospitals to triage patients.

Influenza-like-illness rose above normal levels and continued to stay well above normal for 15 consecutive weeks.

The levels of pneumonia and influenza diagnosis rose above the epidemic threshold at the beginning of January 2013 and peaked at 9.9 percent, making it the highest recorded pneumonia and influenza diagnosis in almost a decade.

The flu shot was available last year, but seemed a  poor match to this raging flu season.

With the 2013-2014 flu season right around the corner, a new high-dose influenza vaccination may prove to be more effective, particularly for the elderly.

High-dose Flu Shot

Sanofi Pasteur, one of the approved manufacturers of influenza vaccinations, said they plan to submit a study on the clinical trial describing the effectiveness of the high-dose flu shot to the United States Food and Drug Administration. Sanofi plans to have the study in by early 2014.

Sanofi says they included nearly 30,000 participants in the clinical trial, and found that the high-dose influenza vaccine called, Fluzone High-Dose vaccine was 24.4 percent more effective in preventing influenza among those 65 years and older compared to the Fluzone vaccine.

However, this isn’t a new vaccine, Fluzone High-Dose vaccine was licensed for sale by the FDA in 2009 under an accelerated approval process, which required Sanofi to complete a large-scale confirmatory study.

High-Dose Flu Vaccine

The Fluzone High-Dose vaccine is for those ages 65 years and older and is made up of three strains of influenza, just like the other flu shots. The difference is that it contains as much as four times the flu virus antigen (the part that stimulates the immune system).

According to the Mayo Clinic, older people produce 50 to 75 percent fewer antibodies than younger adults. According to the Mayo Clinic, studies have found that patients who received the Fluzone High-Dose vaccine had higher post -vaccine antibody levels than those who received the standard flu shot.

However, people who received this more potent vaccine were also more likely to have side effects including a sore arm from where the vaccine was injected, and fever, during the week that they received the vaccine.

The elderly are at a higher risk for contracting the influenza virus. Image by the CDC.

The elderly are at a higher risk for contracting the influenza virus. Image by the CDC.

Flu Vaccine Studies

So is this high-dose vaccine working? In one of the earlier studies published in the Journal of Infectious Diseases, a randomized, double-blinded control study was conducted to compare the high-dose vaccine with the standard dose vaccine.

The high dose vaccine contains 60 μg of hemagglutinin per strain and the standard vaccine contains 15 μg of hemagglutinin per strain. The high-dose vaccine was given to 2,575 people and the standard vaccine was given to 1,262 people.

Researchers found that after 28 days, the people that received the high-dose vaccine, there was a significant increase in the antibody response compared to those who received the standard dose. There were also no increases in the rate of severity in adverse reactions.

In another study published in the Clinical Infectious Disease Journal, researchers examined the adverse reaction of the Fluzone High-Dose vaccine by using the Vaccine Adverse Event Reporting System (VAERS).

Researchers looked for people ages 65 years and older who received that high-dose vaccine or the standard vaccine from July 1, 2010 to December 31, 2010, and found in that the VAERS received 606 reports and 8.2 percent resulted in serious events. After clinical review of the serious reports, researchers found that gastrointestinal were more common among those who received the high-dose compared to the standard dose.

Researchers also found that a higher proportion of cardiac events were noted among those who received the high-dose vaccine. The reporting rates for Guillain-Barré syndrome and anaphylaxis were no higher than those who received the standard dose. Researchers concluded that during the first year of the high-dose vaccine, no new safety concerns were identified via the VAERS.

Fluzone High-Dose Vaccine

There have been multiple studies on the Fluzone High-Dose vaccine, and studies will continue to test safety and effectiveness. If the Fluzone High-Dose vaccine continues to be effective in studies, then this vaccine may become the vaccine of choice for those who are 65 years and older.

Resources:

Centers for Disease Control and Prevention. Seasonal Influenza 2012-2013 drawing to a close. (2013). Accessed August 26, 2013.

Falsey, A., Treanor, J., Tornieporth, N., et. al. Randomized, Double-Blind Controlled Phase 3 Trial Comparing the Immunogenicity of High-Dose and Standard-Dose Influenza Vaccine in Adults 65 Years of Age and Older. Journal of Infectious Diseases. Volume 200, Issue 2. (2009). Accessed August 26, 2013.

Mayo Clinic. Fluzone High-Dose: How is it different? (2011). Accessed August 26, 2013.

Moro, P., Arana, J., Cano, M., et. al. Postlicensure Safety Surveillance for High-Dose Trivalent Inactivated Influenza Vaccine in the Vaccine Adverse Event Reporting System, 1 July 2010–31 December 2010. (2012).Volume 54, Issue 1. Accessed August 26, 2013.

Reuters. URGENT-Sanofi trial shows Fluzone high-dose flu vaccine efficacy. (2013). Accessed August 26, 2013.

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