FDA panel recommends strains for 2013-2014 flu vaccine

Sandra A. Fryhofer, MD

Much thought and study goes in to deciding which influenza strains to include in the influenza vaccine for the next season. Next season, more quadrivalent vaccine will be available which offers opportunity for greater protection against flu. One question is, now that the vaccine is available earlier (due to new methodologies, and production and manufacturing technologies-) when is the ideal time to administer the vaccine?  In addition, we still need to figure out why seniors had such poor immunogenicity to some components of the 2012-2103 vaccine. This is not entirely clear. Immunosenescence has a role.  As we age, our immune system also ages and does not work as well. This phenomenon was the impetus for the high dose flu shot for seniors, a way to boost immune response.  This season’s nonsignificant vaccine effectiveness against influenza A (H3N2) for seniors also demonstrates the need for better and more effective vaccines (especially for this older age group) and the importance of antiviral medications in symptomatic individuals, regardless of vaccination status.

William Schaffner, MD

Depending on the study, this year’s influenza vaccine was about 50% to 70% effective, confirming what we already knew from similar studies in previous years:  influenza vaccine is a good, but not a great vaccine.  In this context, I like to paraphrase the French philosopher Voltaire who admonished us that, “Waiting for perfection is the great enemy of the current good.”  Indeed, much good results from the use of the current influenza vaccine; it prevents many illnesses, hospitalizations and deaths each year through its widespread use. We ought to use it even more widely, taking heed of the CDC’s recommendation that everyone older than 6 months of age be vaccinated against influenza each year.

This coming year another step will be taken to improve influenza vaccine. Some of the manufacturers will be producing a quadrivalent vaccine, containing antigens against two influenza A strains and two influenza B strains. As of this writing, the nasal spray vaccine produced by MedImmune will be entirely quadrivalent and some of the injectable vaccine made by GlaxoSmithKline is scheduled to be quadrivalent. The additional protection against influenza B is noteworthy; this past season an influenza B strain that was not included in the vaccine was responsible for 6% to 10% of cases of influenza. Influenza B viruses are much less likely to produce large outbreaks of influenza than are influenza A strains, but they produce disease throughout the season, often particularly near the end of the season as influenza A cases are abating.