In a recent public health advisory, the US Centers for Disease Control and Prevention (CDC) predicts the respiratory syncytial virus (RSV) activity for the upcoming winter season and encourages clinicians to adopt and implement recent RSV prevention tools. 

Advisory: Increased Respiratory Syncytial Virus (RSV) Activity in Parts of the Southeastern United States: Latest Prevention Tools Available to Protect Patients, Distributed via the CDC Health Alert Network, September 05, 2023, 2:00 PM ET CDCHAN-00498. Image Credit: Pete Hansen / Shutterstock.com

Background

Yearly, the CDC issues a health advisory for the general public and clinicians throughout the US through its Health Alert Network (HAN) regarding RSV activity. RSV, a ribonucleic acid (RNA) virus, causes severe respiratory infections in infants, children, and older adults.

Prior to the coronavirus disease 2019 (COVID-19) pandemic, the annual RSV season within the U.S. began in the autumn and sometimes reached its peak by winter. On account of mitigation measures implemented throughout the pandemic, RSV spread reduced between May 2020 and March 2021; nevertheless, the spread of RSV eventually returned to its typical seasonal trend. 

Nevertheless, in 2021, RSV began spreading in May, peaked by August, and continued through December. In 2022, RSV again became lively in the summertime but peaked in October and November, declining rapidly by winter. 

Unlike its onset timing, post-pandemic RSV activity follows the identical geographic pattern as before the pandemic in 2021-2022. More specifically, RSV often begins to spread in Florida, moving throughout the southeast after which spreading further to the northern and western U.S.

In 2023, the CDC observed increased RSV activity within the southeastern U.S. in late August. In response to the National Respiratory and Enteric Virus Surveillance System (NREVSS) data, the weekly percentage of polymerase chain response (PCR) test-based positive detections remained below the season’s onset threshold of three% for 2 weeks. 

In Georgia, rates of RSV-associated hospitalizations increased, whereas in Florida, the three-week PCR positivity moving average was over 5% from the week ending July 22, 2023. 

Latest tools for RSV prevention

In 2023, nirsevimab, in addition to RSVPreF3 and RSVpreF vaccines, became available to the general public since their recent approval. Nirsevimab is a U.S. Food and Drug Administration (FDA) approved long-acting monoclonal antibody (mAb) that’s currently indicated for infants younger than eight months, in addition to children between eight to 19 months of age who’re at a high risk of severe illness resulting from RSV infection. Clinical trials have established that a single intramuscular injection of nirsevimab is secure, effective, and will protect infants for at the very least five months.

The CDC asked clinicians to seek the advice of local, territorial, or state authorities on the timing of nirsevimab use, especially in regions with less predictable RSV seasonality. Current recommendations for nirsevimab include one dose for all infants ages eight months or younger entering their first RSV season or born during this time, throughout the first week of birth, and one other as early as possible during their first RSV season. The prescribed dose is 50 and 100 mg for infants weighing lower than five kilograms (kg) and over five] kg, respectively. 

The CDC also recommends that children between eight and 19 months of age who’re at an increased risk of RSV infection, reminiscent of those that are immunocompromised, should receive one dose of 200 mg nirsevimab before entering their second RSV season. 

In response to the American Academy of Pediatrics (AAP) recommendations, children 24 months or younger at the next risk for severe RSV disease could also receive palivizumab mAb until nirsevimab becomes available.

RSVPreF3 and RSVpreF, that are recombinant protein vaccines, have also received FDA approval to be used in adults 60 years and older. In a clinical trial that included 38,177 participants over 60 years of age, these vaccines were related to over 80% efficacy in stopping RSV-related lower respiratory tract disease. The RSVpreF vaccine was also approved to be used in pregnant women between 32-36 weeks.

Clinicians are advised to debate RSV vaccination with their adult patients who’re over 60 years of age. Notably, all vaccines for which a patient is eligible, including those against COVID-19, influenza, and RSV, could also be administered together.

Adults with advanced age and specific chronic medical conditions, reminiscent of chronic obstructive pulmonary disease (COPD), might profit probably the most from vaccination. Clinicians must also consider testing symptomatic patients to tell patient management and ask those testing positive to remain home to stop onward viral transmission.

Conclusions

RSV causes between 58,000-80,000 and 60,000-160,000 hospitalizations in children five years and younger and adults aged 65 years and older, respectively, yearly within the U.S.

Given its increased activity within the southeastern U.S. in August 2023, healthcare service providers must remain prepared and informed and take preventive measures to scale back the chance of RSV-related hospitalizations and death.