The 2023-2024 flu season in the United States, after a relatively subdued beginning, has experienced a significant surge, impacting various regions with varying intensity. The Centers for Disease Control and Prevention (CDC) reported a “very high” level of emergency room visits related to influenza in the last week of December 2023, exceeding the hospitalization rate for COVID-19 by a factor of two. The elderly population has borne the brunt of this flu season, with a disproportionately high number of hospitalizations among seniors.
This surge in flu activity has reached “high” or “very high” levels across a vast swathe of the country, encompassing 40 states. The Southern states and the Pacific Northwest have been particularly hard hit, with Oregon experiencing a peak in flu-related emergency room visits exceeding even the previous winter’s surge. Sara Hottman, a spokesperson for Oregon Health & Science University Hospital, highlighted the significant increase in flu cases in December 2023 compared to the same period in the previous year, illustrating the severity of the current outbreak. Besides Oregon, other states experiencing extreme flu activity include Idaho, New Mexico, Louisiana, Alabama, and Tennessee. New York also faces a “high” level of flu activity, with New York City surpassing other parts of the state in reported cases.
Despite the widespread surge, certain areas within the Northeast and Midwest have been relatively spared. States like South Dakota, Delaware, and West Virginia reported “low” levels of flu activity, while Montana and Vermont recorded the lowest levels in the country. This regional variation underscores the dynamic nature of flu transmission, influenced by factors such as climate, population density, and individual preventative measures.
Flu season typically spans from October to April or May, coinciding with colder, drier weather conditions that favor the virus’s survival and transmission. The virus thrives in these conditions and can spread more easily among individuals in enclosed spaces. Common symptoms include fever, chills, sore throat, dry cough, headaches, muscle aches, runny or stuffy nose, and fatigue, which can range in severity from mild discomfort to debilitating illness.
As of December 28, 2023, the CDC estimates that the current flu season has resulted in at least 5.3 million illnesses, 63,000 hospitalizations, and 2,700 deaths, including 11 pediatric fatalities. These figures emphasize the significant impact of the flu on public health and the importance of preventative measures. The American Heart Association recommends annual flu vaccination for individuals over six months of age, along with preventive practices such as avoiding close contact with sick individuals, refraining from touching the face, frequent handwashing, and seeking prompt medical attention if flu symptoms arise. Early intervention and treatment can significantly improve outcomes and reduce the severity of the illness.
While the flu has taken center stage this winter, it is not the only respiratory illness affecting the US population. The CDC reports increasing COVID-19 activity in most regions, along with “very high” levels of respiratory syncytial virus (RSV) activity, particularly among young children. However, experts have downplayed the likelihood of a “tripledemic” overwhelming hospitals, attributing this partly to the relatively slow uptick in COVID-19 cases.
The possibility of co-infection, where individuals contract two respiratory viruses simultaneously, exists. However, virologists have observed a phenomenon known as viral interference, where one virus can hinder the infection of another. This interaction between different viruses can influence the overall severity and dynamics of respiratory illness outbreaks. Although co-infections can occur, the interaction between viruses like influenza and COVID-19 often leads to one virus dominating the infection, which could potentially mitigate the severity of a feared “tripledemic.”
In summary, the 2023-2024 flu season has presented a significant public health challenge, marked by a substantial surge in cases across many regions of the United States. While certain areas have experienced lower levels of activity, the overall impact has been substantial, particularly among the elderly population. Alongside the flu, the presence of COVID-19 and RSV adds complexity to the respiratory illness landscape. However, the likelihood of a “tripledemic” overwhelming hospitals appears to be low, partly due to the relatively slow increase in COVID-19 cases and the phenomenon of viral interference. Continued adherence to preventative measures, such as vaccination and hygiene practices, remains crucial in mitigating the spread and impact of these respiratory illnesses.
