Overview of This Year’s Influenza Season

Seasonal influenza remains a significant public health concern, with widespread community transmission observed each year. Even individuals who have not personally experienced influenza this season are likely to know someone who has been affected.

According to estimates from the Centers for Disease Control and Prevention, between early October and late January of the current season, there have been at least 22 million illnesses, 280,000 hospitalizations, and 12,000 deaths in the United States. Importantly, influenza activity remains ongoing, and the season has not yet reached its conclusion.

In comparison, the 2021–2022 influenza season—considered relatively mild—was associated with approximately 11 million illnesses, 120,000 hospitalizations, and 6,300 deaths. These comparisons underscore the increased severity and impact of the current season.

To better understand the factors contributing to influenza transmission and severity, as well as effective prevention strategies, this discussion provides insights into patterns of spread, reasons for heightened activity this season, and evidence-based approaches to reducing risk.

Etiology and Clinical Presentation of Influenza

Influenza is caused by infection with influenza viruses, most commonly types A and B, which are RNA viruses responsible for seasonal outbreaks.

The clinical presentation is typically characterized by the abrupt onset of systemic symptoms, including fatigue, malaise, fever, myalgias, and cough. Patients often report significant weakness and reduced functional capacity, which may interfere with routine daily activities.

Influenza is frequently distinguished by its rapid onset and the intensity of symptoms, which can develop quickly over a short period. In otherwise healthy individuals, the illness is generally self-limited and resolves within several days, although symptoms such as fatigue may persist for a longer duration.

Understanding Influenza Transmission

Influenza is transmitted primarily via the respiratory route, through virus-containing droplets and aerosols released when infected individuals cough, sneeze, speak, or breathe. These particles can be inhaled by others, leading to infection.

Transmission through contact with contaminated surfaces (fomites) is also possible, although it is considered a less common route. In such cases, the virus may be transferred to the mucous membranes when an individual touches a contaminated surface and subsequently touches the nose, mouth, or eyes.

Factors Contributing to Increased Influenza Severity This Season

The increased severity of the current influenza season is likely multifactorial. A key contributing factor is the predominance of the Influenza A (H3N2) subtype, which has historically been associated with more severe clinical outcomes compared with other circulating strains. Additionally, the emergence of a newer viral variant (subclade K) later in the season may have reduced the overall effectiveness of the current vaccine due to incomplete strain matching.

Vaccine uptake has also been lower than optimal, resulting in reduced population-level immunity and increased susceptibility to infection. Lower vaccination coverage can contribute to higher transmission rates and greater disease burden across communities.

Furthermore, public health behaviors adopted during the COVID-19 pandemic—such as mask use, physical distancing, and avoidance of large gatherings—have declined. The reduction in these precautionary measures has likely facilitated increased viral transmission during the current influenza season.

Effective Strategies for Influenza Prevention

Effective protection against influenza relies on a combination of preventive measures rather than a single intervention. A layered approach to prevention can significantly reduce the risk of infection and transmission.

Key strategies include:

• Vaccination, which remains the most effective method for reducing the risk of severe illness and complications
• Mask use in crowded or poorly ventilated environments, or avoidance of such settings when feasible
• Hand hygiene, including regular handwashing with soap and water or the use of alcohol-based sanitizers
• Respiratory etiquette, such as covering coughs and sneezes
• Staying home when symptomatic to limit the spread of infection

Importantly, many of the public health measures implemented during the COVID-19 pandemic—including masking, improved hand hygiene, and social distancing—are also effective in reducing influenza transmission.

Greater adherence to these preventive behaviors at the population level has the potential to substantially decrease the overall burden of influenza and reduce seasonal outbreaks.

High-Risk Populations for Influenza and Recommended Preventive Measures

Certain populations are at increased risk for severe influenza-related complications. These include older adults, young children, pregnant individuals, and those with weakened immune systems or underlying chronic medical conditions.

In addition to vaccination, individuals in these higher-risk groups should adopt enhanced preventive measures. These include minimizing exposure to crowded or poorly ventilated indoor environments, wearing masks in higher-risk settings, maintaining strict hand hygiene, and practicing appropriate respiratory etiquette. Early medical evaluation is also recommended if symptoms develop, as timely intervention may reduce the risk of complications and improve clinical outcomes.

Timing of Influenza Vaccination: Is It Too Late in the Season?

It is not too late to receive the influenza vaccine. Although vaccination is ideally administered in early fall—typically around October—to ensure optimal protection before peak transmission, vaccination later in the season remains beneficial.

In the United States, influenza activity generally occurs between October and April or May, with peak incidence often observed during the winter months. February is frequently among the highest peak periods for influenza transmission.

Even when the vaccine does not perfectly match all circulating strains, it continues to provide meaningful protection. Vaccination has been shown to reduce the severity of illness, decrease the risk of hospitalization and complications, and offer protection against multiple influenza virus strains that may be circulating during the season.