U.S. flu activity continues slow increase

The proportion of U.S. outpatient visits for influenza-like illness (ILI) crept up from 2.1% to 2.2% for the week ending Jan. 23 – week 15 of the 2015-2016 flu season, the Centers for Disease Control and Prevention reported.

That increase put the proportion of visits involving ILI back above the national baseline level of 2.1% for the first time since the week ending Jan. 2, when it reached a season-high 2.8%, the CDC said.

Puerto Rico was the nation’s influenza hotspot at level 8 on the CDC’s 1-10 scale of ILI activity, but the states with the most activity were Connecticut, Maryland, and South Carolina, which were categorized in the “moderate” range at level 6. Connecticut was up from level 2 the week before; the other two states were unchanged.

There were five states in the “low” range: Arizona, New Jersey, and Oklahoma at level 5 and Illinois and Virginia at level 4. Arizona (down from level 7) and Oklahoma (up from level 3) were the biggest movers in this group from the previous week. There were 12 states at level 3 and four states at level 2, putting the total at 24 states at level 2 or higher, according to data from the CDC’s Outpatient Influenza-like Illness Surveillance Network.

There were no pediatric deaths reported in week 15, keeping the total for the season at seven, the CDC said, which is well below the number of deaths reported by week 15 in each of the last three flu seasons.

The ILI hospitalization rate for the season so far is 2.1 per 100,000 population, with 575 laboratory-confirmed, influenza-associated hospitalizations reported between Oct. 1, 2015, and Jan. 23, 2016. The highest hospitalization rates are among adults aged 65 years and older (7.0 per 100,000 population) and children aged 0-4 years (3.4 per 100,000), the CDC reported.

rfranki@frontlinemedcom.com