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September 29, 2023

Increased Respiratory Syncytial Virus (RSV) activity in southeastern United States: New prevention tools available to protect patients

Actions requested

  • Be aware of increased RSV activity in parts of the Southeastern United States and anticipated spread to northern and western parts of the continental United States.
  • Prepare to implement, recommend and offer new RSV prevention options when they become available this season:
    • RSV monoclonal antibody (nirsevimab) for all infants ages <8 months, and infants and children ages 8–19 months who are at increased risk of severe RSV (expected availability mid October through the Washington State Childhood Vaccine Program)
      • All infants ages <8 months born during or entering their first RSV season should receive 1 dose of nirsevimab.
      • Infants and children ages 8–19 months who are at increased risk for severe RSV disease, such as those who are severely immunocompromised, should receive 1 dose of nirsevimab shortly before entering or during their second RSV season.
      • Consider palivizumab for children <24 months of age with certain conditions that place them at increased risk for severe RSV disease where nirsevimab is not available.
    • RSV vaccine to adults 60 years and older using shared clinical decision-making.
      • Adults ≥60 years may receive a single dose of RSV vaccine (RSVPreF3 or RSVpreF)
      • Prioritize vaccination in patients with chronic medical conditions associated with increased risk of severe RSV disease (e.g., heart disease, lung disease, and immunocompromising conditions).
    • RSV vaccine (RSVpreF) to pregnant people between 32-36 weeks of gestation for prevention of RSV complications in infants from birth through 6 months of age.
    • Update patient vaccine records including administration of nirsevimab and RSV vaccines in the Washington State Immunization Information System (IIS).
  • Recommend and offer coadministration of vaccination against influenza and COVID-19 for all patients 6 months and older who are not up to date.
  • Remind patients that layered approaches including vaccination, masking and improving ventilation remain critical to mitigating risk of COVID-19 and other respiratory viral infections, especially among high-risk individuals.
  • Prepare for stress on the healthcare system from increased hospitalizations related to respiratory infections.

Background

In the United States, the annual RSV season has historically started and peaks in the fall and winter months. However, this pattern was disrupted during the COVID-19 pandemic, likely due to public health measures to reduce the spread of COVID-19 that also reduced the spread of RSV and other respiratory viruses. Notable trends in RSV activity were seen with limited activity in 2020 and an atypical season in 2021 with a late spring start followed by a peak in the summer and continued through the end of 2021. In 2022, RSV activity began in the summer, peaking across the United States in the fall and rapidly declining in the winter. Despite the disruptions in timing, RSV activity continued its geographic pattern of starting in Florida and the southeast before spreading to northern and western parts of the continental United States in 2021 and 2022.

In recent weeks, CDC has observed an increase in RSV activity in parts of the Southeastern United States,  according to the National Respiratory and Enteric Virus Surveillance System (NREVSS) data. According to RSV-NET, a population-based surveillance system, RSV-associated hospitalization rates in the Southern United States started increasing for children <4 years of age in late August.  

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