CDC: No change in flu activity, numbers grow slowly

Feb 12, 2010 (CIDRAP News) – For the third week in a row pandemic flu activity stayed at the same level, with mixed signals from other indicators: flu and pneumonia deaths dropped below baseline, though doctor visits for flulike illnesses were above baselines in three regions, the US Centers for Disease Control and Prevention (CDC) said today.

Alongside today's weekly surveillance update, the CDC issued new estimates of disease burden through Jan 16, which show small increases in illnesses, hospitalizations, and deaths, reflecting generally low flu activity in the United States over the past 5 weeks.

In today's report the CDC estimated that 57 million people, or nearly 19% of the population, have been infected and 11,690 have died from the pandemic virus. That compares with the CDC's previous estimates of 55 million cases and 11,160, covering the period from April through Dec 12.

According to the CDC's surveillance report for the week ending Feb 6, no states reported widespread activity, and six reported regional activity, the same as for the previous week. States reporting regional activity were Alabama, Georgia, Maine, New Jersey, New Mexico, and South Carolina.

Though visits to doctors for flulike illnesses remained below the national baseline, in three regions the number of visits rose above area baselines: the region that includes eight southeastern states, the Midwestern region that includes Iowa, Kansas, Missouri, and Nebraska, and the southwestern region that includes Arizona, California, Guam, Hawaii, and Nevada.

For the first time in 4 weeks, deaths from pneumonia and influenza dropped below the national baseline. The number of pediatric deaths also dropped from the nine listed in the last surveillance report to three. Two of the children had lab-confirmed pandemic H1N1 infections and one had an influenza A virus of undetermined subtype that was probably the pandemic virus.

In its updated pandemic burden report today the CDC estimated that hospitalization have risen to 257,000, compared to 246,000 the previous month. It put the number of deaths at 11,690, up from 11,160 in the previous report.

The CDC estimated that 19 million cases occurred in children up through age 17, which represents about 26% of this age-group, leading to 82,000 hospitalizations and 1,230 deaths. For adults aged 18 through 64, the estimate is 33 million cases, representing about 17% of this population, 150,000 hospitalizations, and 8,980 deaths.

For people 65 and older, who are believed to have some protection from past flu exposures, the new estimates remained at about 5 million cases, which is about 13% of this population, with hospitalizations rising to 25,000 and deaths to1,480.

The CDC in its report today said that uncertainty surrounds what will happen during the rest of the flu season. However, updated estimates continue to suggest that those younger than age 65 are more severely affected by the pandemic H1N1 virus, a pattern not seen with seasonal flu, the agency said. With seasonal flu, 60% of hospitalizations and 90% of deaths occur in people 65 and older, but during the H1N1 pandemic 90% of hospitalizations and 87% of deaths were in people younger than 65.

The agency continues to recommend H1N1 vaccination for everyone aged 6 months and older, including those 65 and older, because severe illnesses and deaths have occurred in the older age-group.

In its most recent vaccine supply update on Feb 2, the CDC said more than 147 million doses were available to states, of which 119 million have been ordered.

See also:

Feb 6 CDC influenza update

CDC estimates of H1N1 cases, hospitalizations and deaths through Jan 16
http://www.cdc.gov/h1n1flu/estimates_2009_h1n1.htm

US Census Bureau data

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