CDC: High flu activity remains throughout US

Flu activity remains elevated in all regions of the United States, the Centers for Disease Control and Prevention (CDC) said in today's FluView surveillance report .

More pediatric deaths, elderly hospitalizations

Six more children died from flu this past week, bringing the season's pediatric death total to 40. In addition to the very young, the elderly are most at risk from complications of this year's flu.

The CDC said there have been more hospitalizations and clinical visits for influenza-like illness (ILI) at this point in the flu season than in 2012-13, another season when H3N2 strain predominated. The CDC said the cumulative overall rate is 39.4 hospitalizations per 100,000 people. During the 2012-13 flu season, the rate was (38.2 per 100,000).

As of last week, the hospitalization rate among people 65 years and older is 180.2 per 100,000 population. The hospitalization rate for people 65 and older for the same week during the 2012-13 flu season was 165.6 per 100,000. Years in which the H3N2 strain dominates tend to hit elderly people the hardest.

Earlier this week, researchers from the CDC published a new study that showed the high-dose trivalent flu vaccine may protect the elderly from severe complications of the flu in H3N2-predominant years.

The hospitalization rates among adults 50 to 64 years old is 38.4 per 100,000, compared with 35.2 per 100,000 in 2012-13. The hospitalization rate among children younger than 5 years is 25.7 per 100,000. That compares with 54.6 per 100,000 in 2012-13.

Widespread geographic activity

The CDC said 43 states and Puerto Rico are reporting widespread flu activity, with 27 states still experiencing high levels of ILI, the same as last week. Four states reported moderate flu activity, while New York City, Puerto Rico and 6 states reported low activity. Thirteen states reported minimal flu activity.

Influenza A constituted 74% of positive lab samples for the week, but influenza B increased from 16.4% in the previous week to 26% last week. Influenza B tends to circulate more widely later in the flu season. Of the influenza A samples that were subtyped, 97% were H3N2 and 3% H1N1.

The CDC said there have been no reports of documented resistance to antiviral drugs in tested samples, and, so far, the majority of tested samples have not drifted from the strains used to make this year’s flu vaccine.

Despite the lack of antigenic drift, the vaccine is conferring protective immunity for about half of recipients, according to the CDC. The modest protection is typical in H3N2-dominant years, and the CDC still recommends vaccination for anyone 6 months old and older.

"Anyone who has not gotten vaccinated yet this season should get vaccinated now," the CDC said.

See also:

Mar 3 CDC FluView

Mar 3 CDC FluView summary

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