US flu scene still tranquil, CDC says

Jan 13, 2012 (CIDRAP News) – Indicators of influenza activity last week stayed in the low range that has prevailed since fall, the Centers for Disease Control and Prevention (CDC) reported today.

The proportion of outpatient medical visits for influenza-like illness (ILI) was 1.4%, well below the national baseline of 2.4%. In addition, all 10 reporting regions had ILI activity below their specific baselines, unlike last week, when three regions edged above the baselines.

Only two states reported any regional spread of flu; seven states had localized spread and 37 cited sporadic cases. The percentage of deaths attributed to pneumonia and influenza remained below the epidemic threshold, and no pediatric deaths due to flu were reported.

Of 3,199 specimens that were tested by surveillance-system labs and reported to the CDC, 3.4% were positive for flu. More than 94% of the flu viruses were influenza A and 5.6% were influenza B. Of the A isolates, about 54% were H3N2, about 5% were 2009 H1N1, and 41% were not subtyped.

Commenting on the continued low flu activity, Lynette Brammer of the CDC's Influenza Division told CIDRAP News this week, "This influenza season does seem to be getting a bit of a late start but it isn't outside what we've seen in the past. If you use the week in which [at least] 10% of the specimens tested in our virologic surveillance system are positive as the start of the influenza season, in the past 29 years influenza has started in January or later in 15 of those years."

See also:

CDC flu activity update

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