Although some areas of the U.S. may be seeing declines in influenza activity, others are seeing increases, and hospitalizations and deaths continue to rise, the CDC reported Friday.
In general, states in the South, Southeast, Midwest, and New England have waning activity and those in the Southwest and Northwest have increasing numbers of cases, the agency said in its report of flu activity for the week ending Jan. 19.
Numbers of hospitalizations and deaths lag behind reported flu cases, however, as it takes time for people to develop the complications from their infections. This past week there was another spike in the proportion of deaths attributed to pneumonia and influenza -- to 9.8 percent from 8.3 percent the week before. That figure remained above the epidemic threshold of 7.3 percent for the third straight week.
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Eight more flu-related deaths among children were reported, bringing the total to 37 -- spread out in 18 states and New York City. The pediatric death toll now exceeds that from the relatively mild 2011-2012 season, when 34 children succumbed to the flu.
The rate of laboratory-confirmed flu-related hospitalizations increased from the week before as well, from 18.8 to 22.2 per 100,000. Half of all hospitalizations have occurred in individuals 65 and older, who are being admitted for the flu at a rate of about 97 per 100,000.
The numbers indicate a continuation of what CDC director Thomas Frieden, MD, MPH, last week called "a worse-than-average season".
The proportion of outpatient visits attributed to flu-like illness was 4.3 percent in the most recent week of data, down from 4.6 percent and 4.8 percent the prior two weeks. That figure remained above the national baseline of 2.2% for the seventh straight week.
There was a decline in the numbers of states reporting high flu-like illness activity -- from 30 states and New York City the week before, to 26 states and New York City for the week ending Jan. 19.
Nearly all states continued to report geographically widespread influenza activity, with Georgia and Tennessee reporting regional activity and Hawaii and the District of Columbia reporting local activity.
The CDC reiterated the continued importance of getting vaccinated, noting that people may have to search in a couple of different places before finding the vaccine, which has proven to be a good match for the circulating viruses.
The agency also stressed the effectiveness of antiviral treatment when used within 48 hours of developing symptoms, particularly for older individuals and others at high risk for flu-related complications.
Testing of influenza strains during the most recent week uncovered the first virus of the season -- a 2009 influenza A(H1N1) virus -- that was resistant to treatment with oseltamivir (Tamiflu). All of the tested viruses were susceptible to the other neuraminidase inhibitor, zanamivir (Relenza).