After a brief respite, influenza cases are once again on the rise across the United States, alongside continued high activity of respiratory syncytial virus (RSV) and, to a lesser extent, COVID-19. The Centers for Disease Control and Prevention (CDC) reported this week, ending , that influenza levels have increased, reversing a three-week decline.
Flu Trends and Geographic Distribution
Currently, 13 states are experiencing an upward trend in flu cases, while RSV cases are increasing in 21 states. Overall levels of acute respiratory illness remain low to moderate in most areas, with Alabama and Arkansas being the exceptions, categorized as experiencing high levels of illness. COVID-19 activity remains relatively stable in much of the country, though levels are growing or likely growing in 11 states.
The CDC’s weekly respiratory virus update and FluView report indicate that influenza A continues to be the dominant strain, although influenza B is gaining traction nationally. Of the 692 influenza A(H3N2) viruses analyzed since , a significant 90.5% belong to subclade K. This variant is notable because it possesses mutations that allow it to partially evade the immunity conferred by the current influenza vaccine formulation.
Hospitalization and Mortality Rates
For the week ending , 4.7% of healthcare visits were attributed to respiratory illness, exceeding the baseline rate. The flu hospitalization rate stands at 59.5 per 100,000 people, resulting in a total of 15,080 admissions. While this represents a downward trend in hospitalizations, the number remains substantial. Tragically, eight additional pediatric deaths were reported this week, bringing the total number of pediatric flu deaths for the current season to 52.
Diagnostic Testing and Positive Rates
Diagnostic testing reveals the following proportions of positive results: 5.3% for COVID-19, 6.3% for RSV, and 18.0% for influenza. These percentages represent an increase from the previous week’s totals of 5.1%, 5.3%, and 17.2%, respectively. Emergency department (ED) visits attributed to respiratory illness show a slight increase for influenza, rising from 3.2% to 3.4% last week, while COVID-19 and RSV ED visits remained stable at 0.7% and 0.5%, respectively.
Looking Back: Influenza Dynamics and Pandemic Impacts
Recent research highlights the significant impact of public health interventions implemented during the COVID-19 pandemic on the dynamics of respiratory pathogens, including influenza. These measures led to a marked decrease in the global prevalence of epidemic respiratory illnesses. The influenza season was classified as moderate in severity, with activity levels returning to pre-pandemic patterns.
A(H5) Bird Flu Situation
While the current focus is on seasonal influenza, RSV, and COVID-19, it’s important to note that the situation regarding avian influenza A(H5) is also being monitored by the CDC. Current information regarding the A(H5) bird flu is available from the CDC.
What This Means for the Public
The increase in influenza cases, coupled with ongoing activity of RSV and COVID-19, underscores the continued importance of preventative measures. While the current influenza vaccine may not offer complete protection against the dominant subclade K variant, it still provides valuable protection against severe illness, hospitalization, and death. Individuals experiencing symptoms of respiratory illness – such as fever, cough, sore throat, and body aches – should consult with a healthcare professional for appropriate diagnosis and treatment.
The CDC continues to monitor these trends closely and provide updated information to the public. Staying informed and practicing good hygiene, including frequent handwashing and covering coughs and sneezes, remain crucial steps in protecting oneself and others from respiratory illnesses.
