FluMist Quadrivalent, a vaccine to prevent seasonal influenza in people ages 2 years through 49 years, has been approved by the U.S. Food and Drug Administration. FluMist Quadrivalent is the first influenza vaccine to contain four strains of the influenza virus, two influenza A strains and two influenza B strains.
In virus classification influenza viruses are RNA viruses that make up three of the five genera of the family Orthomyxoviridae:
The type A viruses are the most virulent human pathogens among the three influenza types and cause the most severe disease. The influenza A virus can be subdivided into different serotypes based on the antibody response to these viruses. The serotypes that have been confirmed in humans, ordered by the number of known human pandemic deaths, are:
- H1N1, which caused Spanish Flu in 1918, and Swine Flu in 2009
- H2N2, which caused Asian Flu in 1957
- H3N2, which caused Hong Kong Flu in 1968
- H5N1, which caused Bird Flu in 2004
- H7N7, which has unusual zoonotic potential
- H1N2, endemic in humans, pigs and birds
Like the already approved FluMist (trivalent), the quadrivalent vaccine contains weakened forms of the virus strains and is administered as a spray into the nose. Each year, the FDA-approved seasonal influenza vaccine includes three strains of influenza virus, two strains of influenza A and one of influenza B.
During a typical influenza season, there may be two different influenza B strains circulating, or the B strain selected for inclusion in the trivalent influenza vaccine may not be the influenza B strain that eventually circulates causing illness. The inclusion of a second B strain in FluMist Quadrivalent increases the likelihood of adequate protection against circulating influenza B strains.
Oseltamivir an antiviral drug, slows the spread of influenza virus between cells in the body by stopping the virus from chemically cutting ties with its host cell; median time to symptom alleviation is reduced by 0.5–1 day. The drug is marketed under the trade name Tamiflu, and is taken orally in capsules or as a suspension.
As of December 15, 2010, the World Health Organization (WHO) reported 314 samples of the prevalent 2009 pandemic H1N1 flu tested worldwide have shown resistance to oseltamivir.
- FDA Approves First Quadrivalent Vaccine To Prevent Seasonal Influenza (bioresearchonline.com)
- Influenza A Virus In Fruit Bats (medicalnewstoday.com)