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Flu Season Continues; Severe for People 65 and Older

CDC and partners urge prompt treatment with anti-flu drugs for very ill and high risk patients

February 6, 2015 –Despite declines in some key indicators, flu remains widespread across most of the country and severity indicators are still high, according to this week’s FluView. Another eight pediatric deaths have been reported this week, bringing the total for the season to 69. Flu activity has been elevated for 11 consecutive weeks nationally and is expected to continue for several more weeks, especially in parts of the country where activity started later.

National influenza-like-illness levels are declining slowly; at a regional level some parts of the country are seeing declines in activity while other parts of the country are seeing increases. An average flu season lasts about 13 weeks (with a range of 1 week to 19 weeks for the past 13 seasons). However, because this season started relatively early, it could last longer than average.

Mismatched H3N2 flu viruses continue to predominate across the country, hitting older people hard. The flu-associated hospitalization rate among people 65 and older this week is the highest rate recorded since CDC began tracking that data in 2005. Overall nearly 60 percent of flu-associated hospitalizations have been among people 65 years and older. At the current rate of hospitalization, more than 92,000 people 65 and older would have been hospitalized in the US so far this season. Nearly 94 percent of all adults hospitalized for flu this season have had at least one reported underlying medical condition; the most commonly reported conditions are heart disease, metabolic disorders including diabetes, and obesity.

Children 0-4 years have the second-highest hospitalization rate so far this season. Like older people, children often fare worse during H3N2-predominant seasons, however the hospitalization rate for that age group this season is similar to what was seen for the same week during 2012-2013, which was the last H3N2-predominant season.

The percentage of deaths due to pneumonia and influenza (P&I) remains elevated, although there was a slight decline from last week.

This season's vaccine reduces the risk of having to go to the doctor from flu infection in vaccinated people by 23%, which is about half of what is usually seen when vaccine viruses and circulating flu viruses are well-matched.

CDC continues to emphasize the importance of prompt antiviral treatment for those who are severely ill and those who are at high risk of flu complications. A meta-analysis published in The Lancet last week reports on the benefits of antiviral treatment, including reducing the risk of hospitalization by 63 percent.

Researchers analyzed individual patient data from nine published and unpublished randomized controlled clinical trials which compared oseltamivir with placebo for treatment of seasonal influenza in adults. This study joins a growing body of observational data which indicates that these drugs have benefit beyond the treatment of uncomplicated influenza and can reduce serious complications from flu including hospitalizations.

Last week, CDC and public health partners including the American Academy of Pediatrics, the National Foundation of Infectious Diseases and the American Medical Association among others issued a letter to providers urging prompt treatment with flu antiviral drugs in people who are severely ill and people who are at high risk of serious flu complications, including people 65 and older and children younger than 2 years. To help medical office staff triage calls from patients with flu-like symptoms and identify when it might be appropriate to initiate antiviral treatment – even before a medical visit – CDC recently published a flowchart online for use by medical offices in evaluating patients by telephone for possible influenza.

While flu antiviral medications have limitations, most notably that they work best when given early in the course of illness, these are the only drugs approved to treat flu illness.