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2018 Influenza Update: No Peak Yet in Sight


René F. Najera, DrPH

February 9, 2018

Rate of ILI, Week Ending 2/3/2018

We're going to have to wait for some good news about this influenza season. That was the message at the close of another reporting week from Centers for Disease Control and Prevention Acting Director Anne Schuchat, MD. On a conference call to release updated influenza numbers for the week ending February 3, 2018, Schuchat told participants that key indicators for influenza activity have continued to increase. In fact, Schuchat noted, we may be on track to surpass recent records for flu activity. 

A key indicator of flu activity is the proportion of outpatient and emergency department visits attributed to influenza-like illness (ILI). That proportion for last week was 7.7%, higher than seen at the peak of the 2003-4 season (7.6%) and as high as the peak of the 2009-10 pandemic influenza season. The rate of influenza-associated hospitalizations was 59.9 per 100,000 population. The highest rate of hospitalizations was among adults aged ≥65 years (263.6 per 100,000 population), followed by adults aged 50-64 (63.1 per 100,000 population) and children aged 0-4 years (40.0 per 100,000 population). Schuchat noted that the rate for nonelderly adults was unusually high, but also that comparisons with previous years is difficult because this statistic for adults has been tracked only since 2010.

About one in ten deaths last week was attributed to influenza or pneumonia. This proportion is likely to increase: its peak usually lags several weeks behind peaks of hospitalizations and ILI. Ten more pediatric influenza deaths were reported last week, bringing the season total to 63. The influenza A H3N2 strain continues to dominate and causes more severe illness than the other circulating strains. Moreover, the vaccine is known to be less effective against the H3N2 strain than some other strains. 

Schuchat offered a few pieces of better news: though there have been spot shortages of antiviral medications used to treat influenza, in general the supply still exceeds the demand. She advised those who are unable to fill a prescription for antivirals at a particular location to call several local pharmacies and healthcare providers to locate the medication. Additionally, some states are reporting a decrease in H3N2 activity and an increase in influenza B and the H1N1 influenza A strain. The vaccine generally is more effective at preventing those types of flu. 

Schuchat encouraged prevention activities, such as getting the influenza vaccine, washing hands frequently, covering coughs, and staying home when ill. 

The full influenza report from CDC is available .


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