US Flu Season at Epidemic Threshold

The recent US Centers for Disease Control and Prevention’s (CDC) surveillance report, stated that this year’s flu season has crossed the threshold for being considered epidemic — that is, the proportion of deaths attributed to pneumonia and influenza (8.5%) through the 122 Cities Mortality Reporting System was above the agency’s epidemic threshold of 7%. The predominance of more severe strains of influenza this season – H3N2 viruses – has been a cause of concern, with approximately half of these viruses being shown to be drift variants that are not covered in the current flu vaccine

The report noted that 19 children had died across the country from influenza and that there was a cumulative rate for the season of 29.9 laboratory confirmed influenza-associated hospitalizations per 100,000 population.

Outpatient surveillance reports for influenza-like illness was 4.4% above the national baseline of 2%. There was also a reported increase in the number of states (from 13 to 22 in only 1 week) reporting a high level of flu activity. In addition, the CDC found that between October and December 2014 there was an overall rate of 9.7 flu-related hospitalizations per 100,000 population.

The CDC report shows that elderly people are the hardest hit by the flu, with 38.3 hospitalizations per 100,000 population among those over age 65.

Most of the hospitalizations were in people with metabolic disorders, cardiovascular disease, and obesity.