Intense Flu Season Arrives Earlier Than Usual

Flu shots are in short supply as the 2012-2013 season ramps up a month earlier than usual, but there are signs that this year's outbreak may peak early as well.

The 2012-2013 flu season is turning out to be far more severe than last year’s and has reached a high degree of intensity and pervasiveness much earlier than usual. Flu shots and a children’s form of antiviral medication are in short supply, but there are signs that the outbreak may have begun to peak.

The rate of flu-related deaths nudged into epidemic territory during the week ending January 5, 2013, according to the Centers for Disease Control and Prevention (CDC), with 7.3% of deaths nationwide due to pneumonia and influenza. This is just above the epidemic threshold of 7.2%. The CDC also reported that 20 children have died of flu-related illnesses this season. However, the portion of doctor’s visits that were due to flu-related conditions declined from 6.0% during the previous week to 4.3% last week, indicating that the spread of flu may have begun to slow. For comparison, the baseline rate is 2.2%, and it peaked at 2.4% during the particularly mild 2011-2012 season.

The early intensity of the flu season has led to high demand for flu shots among those who have not been vaccinated yet. Of 135 million doses of vaccine produced for the season, 128 million have been shipped. As of the end of November 2012, 112 million Americans had been vaccinated. Sanofi Pasteur, the country’s largest provider of flu vaccine, which produced 60 million doses for the current season, recently announced that it had sold out of 4 of 6 versions of its vaccine. According to the Washington Post, Sanofi also announced that it would make a limited amount of vaccine originally intended for distribution outside the United States available here. (Given the length of time required to produce flu vaccine, making more is not an option at this point.)

In addition, Roche, the maker of the antiviral Tamiflu (oseltamivir), has reported shortages of its liquid formulation, used primarily to treat children. However, pharmacists can make a substitute by dissolving capsules of the medication in sweetened liquid. Tamiflu can be used to treat flu if administered within 48 hours of the appearance of symptoms. On December 21, 2012, the FDA expanded the use of Tamiflu to treat children as young as 2 weeks old, although children under a year old must receive a dose calibrated to their weight. (The previous minimum age for use of Tamiflu was 1 year.)

The CDC first observed a rise in flu activity in early December, a month or so before this usually occurs. The dominant flu strain this season is an H3N2 strain, which tends to be more severe than the H1N1 strains that usually dominate. (The 2003-2004 season, during which at least 48,000 people died of flu-related illnesses, was also dominated by an H3N2 strain.) So far, however, no cases have been resistant to Tamiflu, and this year’s flu shot is well-matched to the dominant H3N2 strain. The CDC encourages those who have not received the flu vaccine to get vaccinated if possible. Patients can go to flushot.healthmap.org to find vaccine providers, although they should be sure to confirm that a given pharmacy or other provider has vaccine available before going to get a shot.