CDC Alert Warns of Increasing Flu Activity, Advises Health Providers

US influenza activity has significantly increased over recent weeks, and health care providers should be vigilant about diagnosing and treating patients with the virus, according to a CDC Health Advisory issued recently.

According to the advisory, influenza A(H3N2) viruses have thus far predominated this season. Last year, vaccine effectiveness (VE) against circulating influenza A(H3N2) viruses was estimated to be 32% in the United States, and CDC officials expect that VE could be similar this season.

In a recent surveillance report on the influenza period from October 1, 2017 to November 25, 2017, data indicated that influenza activity was beginning to increase in November, and several influenza activity indicators were higher than is typically seen for that time of year.

As part of the advisory, CDC officials reminded health care professionals that influenza should be high on their list of possible diagnoses for ill patients, and all hospitalized and high-risk patients with suspected influenza should be treated as soon as possible with a neuraminidase inhibitor (NAI) antiviral. Although NAI antiviral medications are most effective in treating influenza when started early, previous evidence has suggested that the medications are underused in outpatient and hospitalized patients.

The alert included several recommendations made by the CDC:

• Antiviral medications for influenza treatment are an important adjunct to annual vaccination. The CDC recommends treatment with NAI to reduce illness and complications of influenza.
• All hospitalized, severely ill, and high-risk patients with suspected or confirmed influenza should be treated with antivirals.
• Antiviral treatment should be initiated as soon as possible after illness onset and should not be delayed even for a few hours to wait for results of testing. CDC officials recommend treatment to be started within 48 hours of symptom onset, although antiviral treatment started later than 48 hours can still be beneficial for some patients.
• The CDC offers a guide to assist providers about influenza testing decisions. Molecular assays are recommended for testing in hospitalized patients with suspected influenza.
• NAI treatment may be prescribed for any previously healthy outpatient with suspected or confirmed influenza who presents within 2 days after illness onset.
• Three prescription NAI medications are approved by the FDA and recommended for use during the 2017-2018 season: Oral oseltamivir, inhaled zanamivir, and intravenous peramivir. Additionally, adamantanes (rimantadine and amantadine) are not currently recommended for antiviral treatment or chemoprophylaxis of influenza A due to high levels of resistance among circulating influenza A viruses, according to the CDC.

The advisory also noted that early diagnosis of influenza can reduce the inappropriate use of antibiotics if bacterial coinfection is not suspected. Since bacterial infections can cause flu-like symptoms, they should be considered and appropriately treated if suspected.

With influenza cases on the rise, pharmacists can play a role in educating patients about prevention strategies and appropriate treatment.

Reference

Seasonal Influenza A(H3N2) Activity and Antiviral Treatment of Patients with Influenza [Health Advisory]. CDC’s website. https://emergency.cdc.gov/han/han00409.asp. Accessed January 2, 2018.