This season's flu vaccine could be largely ineffective against the current form of influenza, but it is too late to change the formula, according to a new announcement.
Every year, a new variety of influenza becomes prominent, and new vaccines must be produced, in order to remain effective against the disease. Because the vaccines need to be developed well before the start of flu season, researchers need to make educated guesses over which forms of the micro-organism will be most common. This year, the virus mutated into a variety not predicted by developers of the vaccine.
The Influenza A H3N2 virus has now been detected in all 50 states, although the current flu season is mild, compared with previous years. Although fewer people than normal are being diagnosed with influenza this season, the H3N2 variety results in more hospitalizations and fatalities than H1N1 or influenza B forms of the virus.
Influenza viruses collected between October 1 and November 22, 2014 were examined, 52 percent of which were found to have "drifted" to different varieties of the organism.
"Most of the drifted H3N2 viruses are A/Switzerland/9715293/2013 viruses, which is the H3N2 virus selected for the 2015 Southern Hemisphere influenza vaccine. These drifted viruses will likely continue to circulate in the United States throughout the season," the Centers for Disease Control and Prevention advised.
Mutated H3N2 viruses were first detected in in March 2014, following a decision by the World Health Organization (WHO) to develop a vaccine aimed toward other varieties of the disease.
Despite limited efficacy of the vaccine against the current form of the flu, the federal government is still advising physicians to continue immunization programs as planned.
The Centers for Disease Control and Prevention is advising physicians to take a three-pronged approach to battling influenza, which they listed in a health advisory. These include continuing vaccinations, the use of antiviral chemoprophylaxis which can help prevent infection, and encouraging social behaviors to help avoid spread of the disease. These include simple measures, such as sick individuals keeping some distance from people who are healthy, and covering mouths and noses when sneezing.
Vaccines can help provide some protection against influenza strains, even those different than those targeted by the immunization.
"The influenza vaccine contains three or four influenza viruses depending on the influenza vaccine - an influenza A (H1N1) virus, an influenza A (H3N2) virus, and one or two influenza B viruses," the CDC stated in a health advisory.
During the 2012-2013 influenza season, 12,337 people were hospitalized with illness related to influenza and 149 children perished from effects of the virus.