The “official” end of the 2013-2014 influenza season ended on March 31. As we reported earlier toward the end of 2013, the CDC and WHO guessed that the North American flu season’s vaccination would contain up to four different flu viruses. We’ll show you how this flu season is winding down, just how bad this flu season has been, and the effectiveness of the 2013-2014 influenza vaccine so far. The official data for how effective the 2013-2014 flu vaccines were are not out yet. Only the mid-flu season vaccine effectiveness report has been released (as discussed below). The 2013-2014 flu season is well over now – although rare cases still do exist – and the 2013-2014 flu vaccine is no longer available. The 2014-2015 flu vaccine shot should be available towards the end of summer/beginning of fall.

Effectiveness Of The 2013-2014 Influenza Vaccine

Back towads the end of 2013, we discussed the 2013-2014 flu vaccine in depth including the ingredients as well as the strains the vaccine was guarding against.

What the 2013-2014 flu shot guarded you from:

1. An Influenza A/California/7/2009 (H1N1) like virus
2, An (H3N2) virus antigenically like the cell-propagated porototype virus Influenza A/Victora/361/2011 strain
3. An Influenza B/Massachusetts/2/2012 – like virus

Most flu shots contained only these three types of viruses. However, some did contain four. For those ones containing four they contained additional protection against:

1. An Influenza B/Brisbane/60/2008 – like virus

Current 2013-2014 Flu Season Activity

March 31 marked the unofficial end of the current flu season. As the Center For Disease Control (CDC) also reports, current flu activity is low and is declining across the United States.

Who The 2013-2014 Influenza Virus Has Been Affecting

Since the beginning of the flu season in October 1, 2013, there have been 8,405 actual laboratory confirmed influenza associated hospitalizations.

How that breaks down in order of those most affected by the flu:

-for ages 65 and older, 72.9 hospitalizations per 100,000 people
-for ages 50-64, 49.5 hospitalizations per 100,000 people
-for ages 0-4, 43 hospitalizations per 100,000 people
-for ages 18-49, 20.4 hospitalizations per 100,000 people
-for ages 5-17, 8.4 hospitalizations per 100,000 people

Overall, approximately 60% of the hospitalizations have been in people 18-64 years of age.

2013-2014 flu update

The rise and fall of the 2013-2014 flu.

About the hospital data collected:

Hospitalization data is collected across 13 states and only reflects 8.5% of the total U.S. population. It does not reflect the actual number of influenza-associated hospitalizations. So, far more cases have occurred than the 8,405 reported.

Effectiveness Of The 2013-2014 Flu Vaccine

According to the CDC, between all of the hospitalizations, 93% were associated with influenza A, 5.9% with influenza B, 0.4% associated with influenza A and B combined. With those who had influenza type A, 97.3% of those were the 2009 H1N1 which was included in this year’s flu vaccine. About 134 million doses of influenza vaccine had been distributed in the United States for the 2013–14 season.

So does that mean the influenza vaccine worked?

Most of the adult patients hospitalized had underlying factors. The most common underlying factors included obesity, metabolic disorders, cardiovascular disease, and chronic lung disease. Only 12% of hospitalizations had no underlying medical conditions. When it came to children, asthma, neurologic disorders, obesity, and chronic lung diseases. About 43% of of hospitalized children had no underlying medical conditions.

According to the CDC’s own data, the effectiveness of 2013-2014 influenza vaccine has only been 61%.

Things to keep in mind:

-Hospitalization data is only analyzed across eight states
-The more chronic diseases a person has, the greater the risk of flu hospitalization
-The effectiveness of the 2013-2014 influenza vaccine is gauged by analyzing data from only 2,319 children and adults who are enrolled in the U.S. Influenza Vaccine Effectiveness Network – interesting considering the amount of people vaccinated was over one hundred million people. Data the CDC collects can’t be reflective of the entire population with a sample size so small.

Was the flu shot effective this year?

Well, that’s for you to decide. If you fell within the 61% margin and had a chronic disease, then you might think so. Cases of the flu are still going around so it should be interesting to see what the end results will be for the 2013-2014 flu season. We’ll of course, have them for you when they’re out.

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1. “Situation Update: Summary Of Weekly FluView.” Centers For Disease Control and Prevention. 4 April 2014. Web. 7 April 2014.
2. “Interim Estimates of 2013-2014 Seasonal Influenza Vaccine Effectiveness – United States, February 2014.” Centers For Disease Control and Prevention. 21 Feb. 2014. Web. 1 April 2014.
3. FluView: Influenza Hospitalization Surveillance Network. Centers for Disease Control and Prevention. Web. 1 April 2014.