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Influenza strains from summer months antigenically similar to current vaccine
CDC. MMWR. 2011;60(36):1239-1242.
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CDC officials reported low levels of influenza activity from May 22 to Sept. 3 in the United States. Most isolates were antigenically similar to influenza vaccine strains in the Northern Hemisphere 2011-2012 vaccine, officials said in a recent Morbidity and Mortality Weekly Report.
During the surveillance period, 0.6% of 20,868 respiratory specimens tested positive for influenza. Of these specimens, 71% were influenza A, of which 2% were H3N2 and 38% 2009 influenza A (H1N1) viruses. This was followed by influenza B viruses (29%).
Overall, influenza viruses were reported across 26 states, with the largest proportion in the southeastern United States, including Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina and Tennessee (52%). This was followed by states in the West, including Arizona, California, Hawaii and Nevada (17%).
In an analysis of worldwide activity, 68 2009 H1N1 virus isolates were collected and analyzed, including two from the United States, 44 from South America, 14 from Asia and eight from Africa.
All strains were antigenically similar to the A/California/7/2009 (H1N1) component of the 2011-2012 seasonal influenza vaccine for the Northern Hemisphere.
“Year-round influenza surveillance provides critical information for planning interventions to prevent and control influenza, developing vaccine recommendations and antiviral treatment guidance, and presenting information to the public regarding the progress and severity of the influenza season,” Lenee Blanton, MPH, of the CDC’s National Center for Immunization and Respiratory Diseases, and colleagues wrote in the report.
Disclosure: The researchers report no relevant financial disclosures.
This report of worldwide summertime influenza activity yielded no big surprises. Influenza activity in the US declined significantly during these months and the surveillance data indicated that almost all of the strains isolated were the same types that are included in the 2011-2012 vaccine, which is also the same as last year’s product. It also found no changes in the resistance patterns, making oseltamivir and zanamivir the antiviral medications of choice. The editorial note that followed reinforces several important points, including (1) the recommendation for vaccinating children 6 months to 8 years of age with a 2-dose series if not previously vaccinated, (2) a review of the various products, including the newly-approved intradermal influenza vaccine, fluzone intradermal, which, however, is not approved for children younger than 18 years, but could be an option for those of you who follow your patients through college, (3) specific guidance for vaccinating patients with a significant history of egg allergy, and (4) instructions for when to suspect the possibility of swine-origin influenza including sample handling and patient treatment.
By the time you read this, you and your staff should have already received your own immunization against influenza. There’s plenty of vaccine available this year so there’s no excuse. We should always set the example.
– James H. Brien, DO
Infectious Disease News Editorial Board member
Disclosure: Dr. Brien reports no relevant financial disclosures.
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