Though flu activity is still high and widespread across much of the United States and five more children have died from flu, the Centers for Disease Control and Prevention (CDC) said today that hospitalization rates and the percentage of deaths due to pneumonia and influenza remain low compared with past seasons.
So far this season, CDC estimates at least 9.7 million flu illnesses, 87,000 hospitalizations, and 4,800 deaths from flu.
"This is likely due to the predominance of influenza B/Victoria and influenza A(H1N1)pdm09 viruses which are more likely to affect children and younger adults than the elderly," the CDC said in its weekly FluView report. "Because the majority of hospitalizations and deaths occur among people age 65 and older, with fewer illnesses among that group, we expect, on a population level, to see less impact in flu-related hospitalizations and deaths."
This week's FluView also shows a dip in influenza-like illness (ILI) outpatient visits, from 7.0% last week to the 5.8%. The CDC said this is likely because patients did not visit healthcare professionals over the holidays, and said it is too early to interpret the decrease in ILI as a sign flu has already peaked.
Thirty-three states reported high ILI in the first week of January, with flu widespread in 46 states and Puerto Rico. In the previous week, 34 states had high ILI activity and 45 states noted widespread flu.
CDC warns of toll on children
Today the CDC also released a Health Alert Network (HAN) advisory, telling clinicians that influenza B/Victoria and A(H1N1)pdm09 viruses are the predominant strains seen this season.
In the HAN advisory, the CDC said that, in previous seasons influenza B has been associated with a higher proportion of influenza-related pediatric deaths. Today the agency confirmed 5 more pediatric deaths, raising the 2019-20 total to 32, of which 21 have been linked to influenza B.
"So far this season, influenza B virus infections account for about half of hospitalizations reported through CDC's laboratory-confirmed influenza hospitalization surveillance network and the majority of reported influenza-associated pediatric deaths," the CDC said in the advisory.
During the first week of January, lab-confirmed flu samples were divided among influenza A (51.8%) and influenza B (48.2%), the CDC said in its FluView report. Of subtyped A viruses, 92.8% were H1N1. Of B viruses, 99% were Victoria lineage.
"Nationally, influenza B/Victoria viruses are the most commonly reported influenza viruses among children age 0-4 years (46% of reported viruses) and 5-24 years (58% of reported viruses), while A(H1N1)pdm09 viruses are the most commonly reported influenza viruses among persons 25-64 years (45% of reported viruses) and 65 years of age and older (48% of reported viruses)," the CDC said.
Hospitalization rates this past week were 14.6 per 100,000 population, which is similar to what has been seen during recent flu seasons at this time of year, the CDC said. Adults over the age of 65 were hospitalized most frequently, at a rate of 33 per 100,000 population, followed by children ages 0 to 4 (26.8 per 100,000) and adults ages 50 to 64 (17.0 per 100,000).
Jan 10 CDC FluView
Jan 10 CDC HAN advisory