With the holidays winding down, flu activity gained steadily last week, according to today's FluView from the Centers for Disease Control and Prevention (CDC). The H3N2 influenza A subtype accounted for the majority (93.5%) of these cases, the CDC reported.
Six more states report high activity
Ten states (Alabama, Georgia, Louisiana, Missouri, New Jersey, New York, Oklahoma, Oregon, South Carolina, and Utah,) New York City, and Puerto Rico reported high influenza activity, a measure of clinic visits for flu. Only four states reported high activity in the previous week.
Another 10 states (Arizona, Illinois, Indiana, Kentucky, Minnesota, Mississippi, Nevada, North Carolina, Pennsylvania, and Virginia) reported moderate activity, five states (Arkansas, California, Michigan, Tennessee, and Washington) reported low activity, and the remaining 25 states experienced minimal influenza-like illness (ILI) activity.
Nine of the country's 10 regions are reporting ILI at or above their region-specific baseline levels.
Twelve states reported widespread geographic flu spread, up from eight states the week before, while regional influenza spread was reported by Guam and 28 states.
Outpatient and hospital visits spike
During the week that ended on Dec 31, 3.4% of patient visits reported through the US Outpatient Influenza-like Illness Surveillance Network (ILINet) were due ILI. This percentage is above the national baseline of 2.2%, and up from the previous week's 2.9%.
Influenza A virus was associated with 87.7% of all flu-related hospitalizations, with influenza B virus accounting for 10.3%. According to FluView, between Oct 1 and Dec 31, the patients with the highest rate of influenza-related hospitalizations were adults age 65 or older (21.1 per 100,000 population), followed by adults 50 to 64 (5.0 per 100,000 population) and children aged 0 to 4 years (4.2 per 100,000 population). The flu hospitalization rate for seniors, a group typically hard-hit when H3N2 is the dominant strain, was up sharply from 12.7 reported the previous week.
Nationwide, 13.7% of respiratory specimens tested for flu were positive in clinical laboratories, up from 10.4% the week before.
More flu activity in Europe
Also today, the European Centre for Disease Control and Prevention's (ECDC) weekly communicable disease report detailed flu developments in Europe.
Influenza is now widespread in 22 of 43 reporting countries, and like the United States, cases are dominated by the H3N2 strain.
The report noted that adults over the age of 65 are being hospitalized at a higher rate than other patient groups. "It is too early to predict the intensity in primary care and the severity in secondary care, but if A (H3N2) continues to predominate, there is a risk that people over 65 years of age will be the most severely affected, possibly increasing pressure on healthcare systems," the report said.
See also:
Jan 6 CDC FluView
Jan 6 ECDC report
