High-Dose Flu Vaccine (HDV)
What is high-dose flu vaccine (HDV)?
In 2009, the U.S. Food and Drug Administration (FDA) approved a high-dose flu vaccine (HDV) for people 65 years of age and older.
The brand name of the vaccine is Fluzone High-Dose and it is manufactured by Sanofi-Pasteur. The vaccine is given as a single injection in the arm like the traditional flu shot, but it contains four times the antigen dose per flu strain compared to the standard-dose vaccine (SDV). The current HDV is trivalent, meaning it contains antigens from three strains of flu virus (two A strains and one B strain). The SDV PAMF is offering a four-strain (quadrivalent) vaccineÂ that protects against four flu strains (two A strains and two B strains). In the future, the HDV may be quadrivalent as well, but not in the current season.
The HDV will be available to patients 65 and older in provider offices at PAMF, during the weekend community clinics, and the daily drop-in flu clinics for the 2016-2017 flu season. Visit PAMF’s flu website for dates and locations of flu clinics.
Why was the HDV for seniors developed?
People 65 and older typically have the highest rates of hospitalization and death from the flu. However, the protection provided by the SDV is not as strong as in younger patients. This might be due to the fact that antibody levels are not high enough with the SDV. Researchers are exploring a variety of ways to boost the immune response in seniors, and increasing antibody levels with HDV is one of them.
Is there evidence that the HDV provides better immunity than the SDV against flu in seniors? Is it more effective?
A study done in seniors during the 2006-2007 flu season comparing HDV and SDV showed higher antibody levels for the two A flu strains with HDV but no difference for the B strain (Journal of Infectious Diseases, 2009; 200:172-180). While encouraging, the study did not address whether the HDV was more effective in actually preventing the flu. In contrast, a more recent study examined the effectiveness of HDV in preventing the flu (New England Journal of Medicine, 2014; 371:635-45). It showed the HDV to be 24 percent more effective than the SDV in preventing laboratory-confirmed flu in persons 65 or older. However, the absolute difference in flu infection between the two groups was small (1.4 percent with HDV vs. 1.9 percent with SDV) thus making the benefit of HDV a relatively modest one. The study did not examine the effect of HDV on preventing serious complications of flu like hospitalization and death. Both studies were randomized, controlled trials and were industry-funded.
Subsequently, two cohort studies examined the effect of HDV vs. SDV in preventing flu-related hospitalization in seniors, a very important outcome. The first found a 22 percent benefit of HDV over SDV (Lancet Infectious Diseases 2015; 15:293-300) while the second suggested this benefit might be limited to patients 85 years of age or older (Clinical Infectious Diseases 2015; 61:171- 6).
Is the HDV safe?
Minor adverse effects may be slightly more common with HDV than with SDV. For example, pain at the injection site and fever above 100.4 degrees are both more common with HDV (36 versus 24 percent, and 1.1 versus 0.3 percent, respectively). A follow up study of adverse effects showed no strong trend in problems with HDV although gastrointestinal symptoms seemed to be more common with HDV. (Post licensure safety surveillance for high-dose trivalent inactivated vaccine in the Vaccine Adverse Event Reporting System, 1 July-31 December 2010. Clinical Infectious Diseases 2012; 54:1608-14). There does not appear to be a difference in major adverse effects between HDV and SDV.
I am a senior. Should I get the HDV?
The Advisory Committee on Immunization Practices for the Centers for Diseases Control and Prevention has not expressed a preference for either the HDV or the SDV for those 65 or older. Both are considered good vaccines for seniors. However, HDV appears to have a modest edge over SDV in preventing flu and possibly hospitalization as well in this age group. Because of this, a number of PAMF physicians prefer HDV over SDV for their senior patients. Meanwhile, HDV comes with a slightly greater incidence of minor side effects but no increase in major side effects. The current HDV, which is trivalent, has not been compared with quadrivalent SDV.