Flu Season as Intense as 2009 Pandemic

Megan Brooks


February 09, 2018

Ten more children have died of influenza in the United States this week, bringing the total to 63, federal health officials with the Centers for Disease Control and Prevention (CDC) said today in their weekly flu update. This flu season is shaping up to be a historically severe one with no end in sight, they continued.

"We were hoping to have better news to share today, but unfortunately it looks like this flu season continues to be particularly challenging. Our latest data tracking information indicates that influenza activity is still on the rise overall, [and] we may be on track to break some recent records," Anne Schuchat, MD, CDC acting director, told reporters.

Influenza is "incredibly difficult to predict and we don't know if we have hit the peak yet," she noted. In the past five seasons, influenza-like illness (ILI) has been elevated for 11 to 20 weeks, "and we are only at week 11 now. We could potentially see several more weeks of increased flu activity," she warned.

On the basis of the latest data, levels of ILI, which are based on outpatient and emergency department visits, are now as high as that seen at the peak of the 2009 influenza A(H1N1) pandemic. "That's a signal of how very intense this flu season has been," Dr Schuchat said.

No Sign Hospitalizations Leveling Off

She also reported that overall hospitalizations are now significantly higher than what's been seen for this time of year at any time since the CDC's current tracking system began almost a decade ago in 2010. "And the rate is approaching the final rate of hospitalizations observed at the end of the most recent severe flu season of 2014-2015," Dr Schuchat noted.

For this week, the overall cumulative hospitalization rate is 59.9 per 100,000, up from 51.4 per 100,000 a week earlier, and "we don't have any signs of hospitalizations leveling off yet," Dr Schuchat said.

She noted that the proportion of deaths attributed to influenza and pneumonia stands at 10.1% — meaning 1 of 10 people who died in the past week died of influenza or pneumonia.

Influenza A(H3N2) viruses continue to be dominant this season. These viruses are often linked to more severe illness, especially among children and people aged 65 years and older. However, the CDC is seeing an increase in the proportion of B viruses circulating, as well as a smaller increase in the proportion of H1 viruses.

Forty-eight states are still reporting widespread geographic influenza activity. Oregon and Hawaii are reporting regional or less widespread activity.

Last week, the West Coast saw declines in flu activity. "This is still true for H3N2 viruses, but some Western states are beginning to see an increase in influenza B activity," Dr Schuchat said, adding that it's "not uncommon for there to be second waves of influenza B activity during an influenza season."

Dr Schuchat said the CDC continues to recommend the influenza vaccine "even this late in the season," as well as simple commonsense good health habits: stay away from people who are sick, stay home from work or school when sick, cover your cough, and wash your hands often.

More information on influenza is available on the CDC's website.

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