Widespread Flu Activity Has Tripled in Two Weeks

The number of states reporting widespread flu activity tripled in just 2 weeks, as flu season continued to ramp up in the final weeks of 2017.

With 36 states experiencing widespread flu activity during week 51 ending December 23, 2017, the United States is seeing a sharp rise in flu since reporting just 12 states with widespread flu activity in week 49. The Center for Disease Control and Prevention’s (CDC) weekly FluView report for week 51 adds 13 new states to the list of those reporting widespread flu since the previous week. The proportion of clinic visits for influenza-like illness (ILI) has continued to rise above the national baseline of 2.2% to 5.0%, and all 10 regions have reported ILI as at or above regional baseline levels.

In response to the increase in flu activity, the CDC issued a Health Advisory on December 27, 2017, about the rising influenza A (H3N2) viruses that have been predominant so far this flu season. In week 51, influenza A viruses made up 89% of all flu-positive respiratory samples, and A (H3N2) has accounted for more than 88% of those. The new alert notes that in previous seasons in which A (H3N2) has been the prevalent virus, the United States saw more hospitalizations and deaths in individuals aged 65 years and older and young children compared with other age groups. Last season, the CDC notes that the annual flu vaccine was about 32% effective against A (H3N2) and that the flu shot is generally more effective against A (H1N1) viruses.

The CDC released the alert to remind clinicians that with increasing influenza activity around the country, flu should be high on their list of possible diagnoses for those who are ill. The alert also advises clinicians that any hospitalized patients and high-risk patients with suspected influenza should be treated as soon as possible with a neuraminidase inhibitor antiviral. “While antiviral drugs work best when treatment is started within 2 days of illness onset, clinical benefit has been observed even when treatment is initiated later,” they note in the alert.

States such as Idaho are feeling the effects of the escalating flu season. Following news reports of 5 more flu deaths in the state last week, Idaho’s Department of Health and Welfare released a statement on January 2, 2018, saying that the state’s flu-related death toll has reached 13 thus far this season; that total is higher than it has been at this time in the last 7 seasons. “Flu is widespread in Idaho and may be especially severe this season,” said state influenza surveillance coordinator Randi Pedersen, in a recent press release. “Unfortunately, this flu season is far from over. Influenza activity typically peaks in Idaho in January or early February. If you haven’t yet gotten the vaccine, it is not too late! Getting vaccinated is the best way to protect yourself and your family from this serious illness.”

In addition, Indiana’s flu deaths for the season rose from 2 to 9 within a week, and Dallas County reported its sixth flu death of the season. With the CDC reporting 3 new influenza-related pediatric deaths in week 51, health officials continue to recommend the flu shot for anyone who is 6 months and older and healthy enough to receive it.