Dec 18, 2009 (CIDRAP News) – The second wave of the H1N1 influenza pandemic continued to fade last week, as the number of states with widespread cases dropped to 11 and reported deaths in children also declined, the Centers for Disease Control and Prevention (CDC) said today.
The CDC also reported finding 15 more cases of oseltamivir (Tamiflu)–resistant H1N1 viruses, but it said those instances remain rare.
States that still reported widespread activity for the week ending Dec 12 were Alabama, Alaska, California, Delaware, Kentucky, Maine, New Hampshire, New Jersey, Nevada, New York, and Virginia. Another 20 states had regional outbreaks, while the rest had only local outbreaks or sporadic cases.
The CDC received reports of nine pediatric deaths from influenza A last week, of which eight were confirmed as H1N1 cases. That compares with 16 deaths, 13 confirmed as H1N1, the week before.
The overall influenza A death toll in children since the start of the pandemic in April has reached 276, the CDC. That includes 212 since the official start of the current flu season on Aug 30. Of those, 172 (81%) were attributed to H1N1, one was influenza B, and 39 were type A viruses that were not subtyped.
The 15 oseltamivir-resistant H1N1 isolates identified last week bring the US total since April to 44, the CDC reported. Since Sep 1, 32 of 2,292 isolates tested by the CDC were resistant, but those numbers overstate the prevalence of resistance, because suspected resistance was the reason for testing in most cases, the report says.
In the CDC's network of sentinel medical providers, the proportion of outpatient visits attributed to flu was 2.6%, down slightly from 2.7% the week before, but still above the national baseline of 2.3%. Five of 10 regions remained at or above their regional baseline for this measure.
The CDC weekly graph shows a sizable drop in flu-related hospitalizations and deaths last week compared with the week before and a mostly steady decline in both over the past 6 weeks. The agency reports 35,309 lab-confirmed flu-related hospitalizations and 1,567 confirmed flu-related deaths since Aug 30.
However, because many patients are not tested and flu contributes to deaths from other causes, the CDC has said the true numbers of H1N1-related deaths and hospital cases are much higher. Last week the agency estimated deaths from April through mid-November at 9,820 and hospitalizations at 213,000.
CDC's Flu View weekly surveillance report
Dec 10 CIDRAP News story "CDC sharply raises H1N1 case estimates; kids hit hard"