After Steady Decline, Influenza Activity Rising Again in US

Troy Brown, RN

April 01, 2020

Influenza cases confirmed in clinical laboratories fell from 14.9% to 6.9%, but visits to healthcare providers for influenza-like illness (ILI) have risen from 5.6% to 6.4%, according to a March 27 report from the Centers for Disease Control and Prevention (CDC).

Healthcare visits for ILI fell steadily from 6.8% in the week ending February 8 to 5.2% in the week ending March 7 before rising for the past 2 weeks.

"More people are seeking care for respiratory illness due to the ongoing COVID-19 pandemic," the CDC reports.

At least 39 million influenza illnesses, 400,000 hospitalizations, and 24,000 deaths from influenza have occurred so far this season.

The overall cumulative hospitalization rate for the season rose from 65.1 to 67.3 per 100,000 population. Hospitalization rates are "higher than most recent seasons," and rates for children aged 0 to 4 years (93.9 per 100,000) and adults aged 18 to 49 years (35.2 per 100,000) are at their highest since the CDC began recording these figures ― higher even than during the 2009 H1N1 pandemic.

Hospitalization rates for children aged 5 to 17 years (24.4 per 100,000) exceed those from "any recent regular season but remain lower than rates experienced by this age group during the pandemic," the CDC explains.

Hospitalization rates were 88.9 per 100,000 population for adults aged 50 to 64 years and 176.8 for adults aged 65 years or older.

Thirty-seven jurisdictions (the District of Columbia, New York City, Puerto Rico, and 34 states) reported high influenza activity, down from 40 jurisdictions the previous week. ILI activity was moderate in 10 states, low in two states (Alaska and Delaware), and minimal in four states (Arizona, Florida, New Hampshire, and Rhode Island).

Geographically, the number of jurisdictions reporting regional or widespread activity fell from 50 to 49. Influenza activity was local in the District of Columbia, Alaska, and Hawaii, and sporadic in the US Virgin Islands.

The percentage of deaths resulting from pneumonia and influenza is at 7.4% ― just above the epidemic threshold of 7.3%. Six more pediatric deaths from influenza were reported this past week, bringing the total for the season to 155. Except for the 2009 pandemic, pediatric deaths are higher than at this point in every season since the CDC began reporting pediatric mortality in 2004–2005.

Influenza A(H1N1)pdm09 viruses are the most frequently reported viruses nationally this season; influenza B/Victoria viruses were predominant nationally until early February.

The CDC continues to recommend antiviral medications for the management of influenza and vaccination for prevention. Virtually all influenza viruses tested this season were responsive to the four influenza antiviral medications recommended by the US Food and Drug Administration.

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