The flu season never receives a warm welcome and as is every year the older and youngest populations continue to be the most affected and the hardest hit by the flu. The severity of the strains of flu have sent more Americans 65 and older to the hospital for admittance since 2005 states the Centers for Disease Control (CDC.) Young children 0-4 years of age are the next hardest hit group with a high hospitalization rate.
The 2014-15 flu season was particularly troublesome as the data for the flu vaccine demonstrates a 23% effectiveness. This the lowest rate of effectiveness since the 2005-06 flu season. What will this flu season bring? The CDC does not predict the length of the flu season, its’ projected severity or the projected effectiveness of the flu vaccine due to the different variables and different strains of flu;
Why Is The Influenza Vaccine Ineffective?
The effectiveness of the influenza vaccine is affected if a mismatch occurs between the flu strains used in the flu vaccine and the virus currently circulating. H3N2 is the main culprit and is a subtype of the influenza A virus, H1N1 flu is also a prevalent flu strain.
The mix of strains in the flu vaccine is determined by recommendations by the World Health Organization. These recommendations are made in February for the next flu season which begins in December of the same year. The influenza vaccine can be less effective for the current season due to a migration of a strain since the original recommendation the prior winter.
Why Isn’t The Flu Vaccine Changed If Ineffective?
The 2014-15 flu season was particularly rough; as early as March 2014 data was showing the strains in the vaccine did not match approximately 17 percent of the virus strain. By September 2014 the strains in the flu vaccine did not match the virus by 50% for the season.
In this case it was attempted to adjust the mix of the flu vaccine due to its’ ineffectiveness against the H3N2 virus. The H3N2 vaccine was adjusted for those living in the southern hemisphere which begins later than the those living in the northern hemisphere. Unfortunately the lead time needed to manufacture the vaccine did not allow manufacturers sufficient time to adjust the H3N2 vaccine for the northern hemisphere.
How Long Is The Flu Season?
According to the CDC the average length of the flu season is 13 weeks; however, the season can fluctuate, last longer, begin earlier or end later depending upon the year. Generally the flu season begins in December and runs through the end of February. However flu cases have been reported in October with the latest cases of the flu occurring in May.
Who Should Be Vaccinated?
The CDC recommends the flu vaccine be administered by the end of October to citizens six months and older; however, you can be vaccinated later if needed. While the flu vaccine does not guarantee you will not contract the flu; immunization can lessen the symptoms. And if you have ever had the flu even a lessening of symptoms would be welcome for a very unwelcome seasonal visitor.