Flu activity dropped nationally for a second consecutive week, but the changing predominance in type from influenza B to A suggests that “it is too early to know whether the season has peaked,” the Centers for Disease Control and Prevention said Jan. 17.
Patients with influenza-like illness (ILI) dropped from 5.7% to 4.7% of all visits to outpatient providers for the week ending Jan. 11, and the proportion of respiratory specimens positive for influenza decreased from 23.6% the week before to 22.9%, the CDC’s influenza division reported.
Despite that overall drop in positive specimens, however, “the percent positive for influenza A viruses increased and some regions are seeing increases in the proportion of influenza A(H1N1)pdm09 viruses compared to other influenza viruses,” the influenza division noted.
Outpatient activity on the state level also was down for the week. There were 23 jurisdictions – 21 states, New York City, and Puerto Rico – at level 10 on the CDC’s 1-10 scale of ILI activity for the week ending Jan. 11, compared with 33 the previous week, data from the CDC’s Outpatient Influenza-like Illness Surveillance Network show.
Indicators of ILI severity have not risen to high levels. “The percentage of deaths attributed to pneumonia and influenza increased from 6.0% to 6.9% but remains below the epidemic threshold” of 7.0% for the week, and the hospitalization rate remains at a fairly typical level for this time of year, the influenza division said.
For the week ending Jan. 11, 7 new ILI-related pediatric deaths were reported, which brings the total to 39 for the 2019-2020 season. Children aged 0-4 years are the second-most likely age group to be hospitalized with the flu (34.4/100,000 population) after adults aged 65 years and older, who have a cumulative rate of 47.6/100,000 for the season, the CDC reported.