Flu activity across the United States remains relatively low, but public health officials are expressing concerns about potential increases in illness as the winter season progresses. According to recent data released by the U.S. Centers for Disease Control and Prevention (CDC), only four states—Colorado, Louisiana, New Jersey, and New York—are currently experiencing high flu activity. Most other regions report minimal or low levels of influenza cases, but the numbers indicate a need for vigilance.
While this winter’s flu season has not yet escalated to severe levels, the CDC notes that certain indicators are trending upwards. Overall, the season remains classified as “mild” to date. The CDC has highlighted a range of respiratory illnesses that tend to surge in colder months, including the flu, common colds, and norovirus, which has shown an increase in cases recently.
Experts Monitor Flu and RSV Trends
Public health experts are particularly cautious about the flu as last season recorded a concerning number of hospitalizations. The flu hospitalization rate reached its highest level since the H1N1 flu pandemic in 2009. In total, there were 288 pediatric flu deaths reported, marking the worst figures for a regular flu season in the United States. This week, the first pediatric flu death of the current season was also reported.
A specific strain of the flu virus, known as A H3N2, is the most frequently reported this season. Historically, this strain has been associated with increased hospitalizations and fatalities among older populations. Alarmingly, approximately 89% of the H3N2 infections analyzed were found to be from a new variant, the subclade K, which differs from the strain included in this year’s flu vaccine. Given that flu seasons often peak in February, the full impact of this mismatch remains unclear.
The CDC continues to recommend annual flu vaccinations for everyone aged six months and older. As of now, about 42% of U.S. adults and 41% of children have received their flu shots this season. While these vaccinations may not completely eliminate symptoms, they are effective at preventing severe cases, as demonstrated by preliminary analyses from the UK.
RSV and COVID-19: Ongoing Health Challenges
Another respiratory virus of concern is respiratory syncytial virus (RSV), which can lead to severe symptoms in infants and the elderly. Traditionally, RSV peaks during December or January, yet this year has shown a delayed onset, with the CDC reporting lower-than-expected cases thus far. Experts, including Dr. Cameron Wolfe from Duke University, anticipate an increase in RSV cases as the season progresses.
Recent advancements in vaccination may be contributing to lower rates of RSV infections. In 2023, new vaccines for pregnant women and older adults, along with monoclonal antibody treatments for infants, were licensed. As of October, approximately 41% of Americans aged 75 and older have received an RSV vaccine, along with 40% of infants.
In parallel, COVID-19 activity remains low following a summer peak. Recent CDC research indicates that the COVID-19 vaccine is effective at preventing severe illness in children, with a reported efficacy of 76% among those aged nine months to four years. For older children aged five to 17 years, the vaccine showed 56% effectiveness in preventing serious symptoms.
Despite this data, vaccination uptake for COVID-19 remains low, with only about 7% of children and 15% of adults receiving the latest vaccine version. In October 2023, the CDC shifted its recommendations, leaving the decision to receive the vaccine up to individuals. This change has drawn criticism from health professionals who argue that the vaccination guidelines should remain robust, given the significant mortality associated with COVID-19, which has contributed to over 1.2 million deaths in the U.S.
As winter progresses, health officials continue to monitor these respiratory viruses closely. The low current flu activity indicates a possible calm before the storm, prompting experts to urge communities to remain vigilant and prioritize vaccination efforts.
