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Respiratory syncytial virus, or RSV, is a member of this trio; it is a common respiratory virus that typically is present in the late fall through early spring. RSV can affect anyone, at any age, and cause symptoms ranging from mild sniffles to severe and life-threatening disease. Most commonly, severe disease occurs in young infants, particularly those under six months of age, and premature infants. Additionally, children (and adults) with compromised immune systems, chronic lung disease, congenital heart disease, or neuromuscular disorders that impair airway clearance are at risk for more serious complications. Adults and the elderly over 65 years of age are also at higher risk for severe disease, particularly if they have underlying medical problems.

Epidemiologically speaking, RSV is the most common cause of lower respiratory tract infection in children under 12 months of age. Historically, hospitalization rates were highest in young infants and children under five years; however, we have observed a larger number of older children requiring hospitalization this season. Additionally, RSV accounts for a large percentage of outpatient visits. As of early December 2022, RSV case counts are climbing higher and earlier than expected for this time of the year; this rise in cases began in early September!

RSV transmission is by direct contact with virus-containing secretions on hands or fomites. (The pesky little single-stranded RNA virus can survive for several hours on hands and surfaces, so wash those hands and stethoscopes!) It also spreads by large droplet aerosolization from coughs and sneezes; there are also reports of airborne spread. RSV typically incubates two to eight days; RSV is contagious even in the one to two days prior to symptom development. Some children shed RSV for up to four weeks after initial infection! Due to varying viral genotypes, reinfection can happen throughout the season, though subsequent infections are typically less severe. Diagnosis is typically clinical, but rapid PCR testing is available. This testing is helpful for infection control purposes but does not largely change management of the illness.

While symptoms often begin mildly, they can quickly worsen and require escalation of care. Typically, children start with upper respiratory tract symptoms of cough, congestion, sneezing, and rhinorrhea (runny nose); fever and loss of appetite are also often present. As the illness progresses it leads to lower tract respiratory illness (LRTI) presenting with wheezing, worsening cough, and increased work of breathing. Bronchiolitis, pneumonia, and even respiratory failure are typical lower respiratory tract sequelae.

In pediatrics, RSV most commonly causes bronchiolitis, but other viruses can lead to this as well. Bronchiolitis manifests as fever, increased work of breathing, tachypnea, cough, and wheezing with crackles and rhonchi heard on lung auscultation. Babies with increased work of breathing will exhibit tachypnea (abnormally rapid breathing), nostril flaring, head bobbing, grunting, wheezing, and retractions. These symptoms follow the typical one-to-three-day upper respiratory infection prodrome. The LRTI symptoms usually peak on days three to five and gradually resolve; the cough (and even wheezing), however, can last up to a month before it finally improves.

The treatment for RSV is largely supportive. Steroids, albuterol, and antibiotics do not routinely provide benefit. In some cases, children may receive these due to other underlying medical problems. Nasal suctioning with saline is the best option for most infants, though tackling a screaming baby to provide frequent suctioning is no picnic. The best time to suction an infant is just prior to feeding and prior to sleeping. A cool mist humidifier can sometimes aid breathing. Due to severe nasal congestion, infants may have a difficult time breast- or bottle-feeding. Smaller feeds that are more frequent can be of benefit. Children over one year of age can take a spoonful of honey prior to sleep to help with cough and to soothe a sore throat.

Children with signs of dehydration, decreased urine output, refusal of foods and fluids, lethargy, and dry mucous membranes require prompt care. Additionally, children with sustained increased work of breathing, apnea, and / or hypoxia require emergent medical evaluation to monitor for respiratory failure. When admitted to the hospital, these children require IV fluid support, oxygen, high flow nasal cannula, positive pressure ventilation, and, in severe cases, intubation and mechanical ventilation. Secondary otitis media and bacterial pneumonias can develop as well, though a viral etiology is the most common cause of pneumonia in children. Infants under two months of age are at highest risk for these sequelae, but with rising RSV case numbers, many older children are also requiring additional respiratory support!

Palivizumab (Synagis) is a monoclonal antibody given intramuscularly to infants at high risk of severe LRTI due to RSV; this injection is given monthly during RSV season. The American Academy of Pediatrics has specific guidelines for palivizumab administration based on gestational age at birth, as well as presence of chronic lung disease, congenital heart disease, and other congenital and/or genetic disorders. Palivizumab is safely given with other vaccines and thus there is no disruption to typical vaccine schedules.

RSV is a significant clinical problem, causing countless illnesses each year. Because treatment is supportive, parents and caregivers are easily frustrated. Consistent education on course, treatment, and illness duration coupled with prompt medical care for moderate to severe illness is helpful as parents navigate RSV waters.

1. Barr, Frederick E. MD, MBA and Barney S Graham, MD PhD. Respiratory Syncytial virus infection: Clinical features and Diagnosis. Edwards, Morven S, MD and Mary Torchia, MD ed. UpToDate. Waltham, MD: UpToDate Inc. www. uptodate.com. (Accessed on December 12, 2022.)

2. Jones, Andrea MD, FAAP, Section on Infectious Diseases, American Academy of Pediatrics. “RSV: When it is more than just a cold.” December 12, 2022. https://www.healthychildren.org/.

3. National Center for Immunization and Respiratory Diseases (NCIRD), Division of Viral Diseases. “Respiratory Syncytial Virus.” December 12, 2022. https://www.cdc.gov/rsv/clinical/index.html

4. Piedra, Pedro O MD and Ann R Stark, MD. Bronchiolitis in infants and children: Clinical features and diagnosis. Edwards, Morven S, MD and Mary Torchia, MD ed. UpToDate. Waltham, MD: UpToDate Inc. www.uptodate.com. (Accessed on December 12, 2022.)