Late-Season RSV Surge Extends Risk Into Spring, Challenging Seasonal Expectations, Expert Says

As winter respiratory virus activity declines, respiratory syncytial virus (RSV) is following an unexpected trajectory. Recent data from the CDC indicate that RSV activity is rising across much of the US later than anticipated, with national levels currently classified as “moderate and increasing.” This atypical trend is raising concerns among clinicians and public health experts, particularly as it prolongs risk for vulnerable populations into the spring months.¹

A Shift in Seasonal Patterns

Traditionally, RSV peaks in the late fall and winter, often declining by early spring. However, CDC surveillance data show that RSV activity has persisted and, in some regions, intensified beyond its usual time frame. Experts note that this shift reflects broader disruptions in respiratory virus seasonality observed since the COVID-19 pandemic.^1,2

The delayed surge challenges the long-standing expectation of a predictable “respiratory season,” complicating clinical preparedness and public health messaging. According to the National Foundation for Infectious Diseases (NFID), these evolving patterns underscore the need for year-round vigilance, particularly as RSV no longer adheres to historical timelines.³

Continued Burden in Pediatric Populations

Despite the later timing, the populations most affected by RSV remain consistent. CDC data indicate that emergency department visits and hospitalizations are highest among infants and children younger than 4 years. RSV remains a leading cause of bronchiolitis and pneumonia in young children, accounting for significant health care utilization annually.^1,4

The extended season raises concerns for families and health systems, as prolonged circulation increases the window of exposure. Pediatric providers may need to maintain heightened awareness for RSV symptoms even as other respiratory viruses, such as influenza, decline.

Often Overlooked Impact on Older Adults

Although RSV is commonly associated with pediatric illness, it also poses a significant risk to older adults. Adults 65 years and older, particularly those with underlying conditions, are at increased risk for severe disease and hospitalization. However, RSV in this population is frequently underrecognized and underdiagnosed.⁵

The NFID emphasizes that the continued circulation of RSV into spring may disproportionately affect older adults, especially as preventive behaviors wane with the perceived end of respiratory virus season.³

Prevention Strategies and Ongoing Confusion

Recent advances in RSV prevention—including monoclonal antibodies for infants and vaccines for older adults—represent significant progress. However, confusion persists regarding eligibility, timing, and access.³

The CDC recommends immunization strategies tailored to high-risk groups, including maternal vaccination during pregnancy and the administration of preventive antibodies to infants. For older adults, RSV vaccines are available, but uptake has been variable, partly due to limited awareness and evolving recommendations.⁵

Pharmacists play a critical role in addressing these gaps by educating patients, clarifying eligibility, and reinforcing the importance of prevention even outside traditional peak months.

Expert Insights From Robert H. Hopkins Jr, MD

In an interview with Pharmacy Times, Robert H. Hopkins Jr, MD, medical director of the NFID, helps put this late‑season RSV spike into context.

Pharmacy Times: What's driving RSV's unusually late timing this season, and what does it signal about how respiratory virus seasons are evolving?

Robert H. Hopkins Jr, MD: RSV seasons vary from year to year in onset, spread, and severity in the US and in other countries. This season started in late September/early October, and we continue to have ongoing spread and severe RSV disease in many areas of the country. There are likely to be many contributing factors, but the degree of contribution of any individual or group of factors is not clear at this time.

Pharmacy Times: What should parents and caregivers know about their young child's RSV risk right now, and what symptoms should prompt them to seek care?

Hopkins: While RSV most commonly causes an uncomplicated respiratory illness (a cold), children in their first year of life and older children with heart and lung disease are at highest risk for severe RSV disease.

If your child is 2 months or younger with a fever or (at any age) has difficulty breathing, poor feeding, or abnormal behavior (excessive sleepiness, irritability, or other unusual behavior), the child needs to be evaluated by a health care professional immediately.

Pharmacy Times: Where does confusion still exist around RSV prevention options—and what's your message to those unsure whether vaccines or monoclonal antibodies apply to them?

Hopkins: All infants should be protected from severe RSV disease in their first RSV season by either maternal immunization (at 32-36 weeks’ gestation) or through receiving a long-acting monoclonal antibody (nirsevimab or clesrovimab) as soon as possible after birth.

Infants with heart and/or lung disease should also receive nirsevimab in their second RSV season to protect them against severe RSV disease.

All adults 75 years and older [and adults aged 50 to 74 years who have risk factors for severe RSV disease] should receive a one-time RSV vaccination to prevent severe RSV disease.

Pharmacy Times: With RSV potentially elevated through April, what should pharmacists keep in mind when counseling patients during this extended season?

Hopkins: RSV prevention is of particular importance because we do not currently have any effective antiviral medications for RSV. Long-acting RSV monoclonals and vaccines are important for adults, pregnant women, infants, and young children at risk for severe disease and remain the first line of defense for persons at highest risk.

Good hygiene practices—handwashing, decontaminating surfaces, and covering coughs and sneezes—are helpful but need to be done consistently to maximize the benefits of these behaviors.

Finally, individuals at high risk who anticipate being in crowded or high-risk conditions should—at least—consider wearing a high-quality and well-fitted mask covering their nose and mouth to provide an additional layer of protection.

REFERENCES

1. Respiratory virus activity levels. CDC. March 20, 2026. Accessed March 24, 2026. https://www.cdc.gov/respiratory-viruses/data/activity-levels.html

2. Respiratory illnesses data channel. CDC. March 20, 2026. Accessed March 24, 2026. https://www.cdc.gov/respiratory-viruses/data/index.html

3. Expert insights on advances in RSV prevention and treatment. National Foundation for Infectious Diseases. June 5, 2023. Accessed March 24, 2026. https://www.nfid.org/expert-insights-on-advances-in-rsv-prevention-and-treatment/

4. Respiratory syncytial virus (RSV) prevention. American Academy of Pediatrics. Updated September 25, 2025. Accessed March 24, 2026. https://www.aap.org/en/patient-care/respiratory-syncytial-virus-rsv-prevention/?srsltid=AfmBOoobA0Dz82SU3pz6Eeu84QPs1eOEZ7UNPz-8v7iBcrm6UPako_T1

5. Clinical guidance for RSV immunizations and vaccines. CDC. August 18, 2025. Accessed March 24, 2026. https://www.cdc.gov/rsv/hcp/vaccine-clinical-guidance/index.html