H3N2: 2013 Flu Season Update on Deaths, Hospitalizations, and Spread of Influenza

The H3N2 flu strain is severe, and still widespread. Image courtesy of the CDC

The H3N2 flu strain is severe, and still widespread. Image courtesy of the CDC

The 2012/2013 flu epidemic continues. On a hopeful note, the Centers for Disease Control and Prevention (CDC) states that it is possible that some areas of the country have peaked, but other parts of the country are still experiencing high levels of influenza-like-illnesses. It is still too early to tell if the country is on the down hill slide of this year’s severe flu season, but time will tell.

Flu: Doctor’s Visits

One way to know how many people may have the flu is by keeping track of the number of doctor visits for Influenza-like Illness (ILI). This week, the CDC reports that the number of people who went to a doctor for influenza-like-illness has decreased from 6.0 percent to 4.3 percent over last week, but those numbers are still well above the national baseline of 2.2 percent. The CDC’s latest Flu News update also reports that 47 states have no reported widespread flu activity – an increase from 41 states from the week before. The number of influenza-like-illnesses is a good indication of how widespread the flu is becoming, so a reduction is good news for the nation.

Flu Hospitalizations

By the end of the week on January 5, 2013 hospitalizations increased by 1,443 from the previous week, bringing the total to 3,710 flu-related hospitalizations thus far. Forty six percent of these hospitalizations have been in people older than 65 years old.

In 2004, the CDC conducted a study where they examined hospital records from 500 hospitals across the United States between the years 1979 to 2001. In the year 2000 there were an estimated 114,000 hospitalizations due to the flu; now the CDC reports on average 200,000 people are hospitalized every year. People are being hospitalized due to flu complications such as respiratory and cardiac problems more frequently. The CDC also discovered in their study that when the strain of influenza A (H3N2) was dominant, there were more hospitalizations.

2013 Flu Deaths

The CDC does not require the reporting of adult deaths from the flu. There are a few reasons for this, including the fact that influenza is very rarely listed as a cause on a person’s death certificate. In addition, the victim may have developed a secondary infection such as pneumonia. Also, influenza can aggravate chronic, pre-existing conditions such as COPD or congestive heart failure.

However, the CDC does estimate the number of deaths that occur because of the flu. To estimate adult deaths the CDC uses two categories on death certificates: pneumonia and influenza (P&I) causes and respiratory and circulatory causes to determine the estimate for flu deaths. Since the flu is so unpredictable, a range of estimated deaths provides a better look at how serious influenza is.

Click to Read Page Two: Pediatric Deaths from the Flu


© Copyright 2013 Janelle Vaesa, MPH, All rights Reserved. Written For: Decoded Science
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  1. James says

    This is the first article I have come across that actually publishes the ILI as opposed to just the spread map. If you look at the data from the CDC, aside from the fact that this seasons struck earlier than usual, the numbers are nearly identical to the 2007 season (ILI peaked at 6% before decreasing each following week). The past 6 seasons we’ve hit the “epidemic” level and had an ILI above the national baseline each year, even during last year’s “mild” season.

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