Respiratory Syncytial Virus (RSV) Infection

BASICS

Definition: Medium-sized, membrane-bound, single-stranded, negative-sense RNA virus causing acute respiratory tract illness in all age groups.
Adults: URTI, may progress to pneumonia, asthma/COPD exacerbation.
Infants/Children: LRTI (bronchiolitis), rarely pneumonia/respiratory failure/death.
Pediatric: 90–95% infected by 24 months; leading cause of pediatric bronchiolitis.

Seasonality: Outbreaks each winter (Oct–Jan).
Morbidity/Mortality: >100,000 annual hospitalizations (US), 2.1 million outpatient visits (children <5 years).
Incidence (Worldwide): ~33 million LRTI/year, ~199,000 childhood deaths.
Hospitalizations: 3.2 million/year (children <5 years).
Post-COVID: Increasing RSV cases.

Family: Paramyxoviridae; subtypes A & B (A = more severe).
Transmission: Direct contact/droplets; incubation 2–8 days.
Immunity: Incomplete; recurrent infections common.
Pathology: Neutrophil-predominant airway inflammation; major cause of asthma/COPD exacerbation.
Genetics: Severity linked to cytokine gene polymorphisms (CCR5, IL4, IL8, IL10, IL13).

Infants: <35 weeks' gestation, low birth weight, male, cardiopulmonary disease, HIV, Down syndrome, no breastfeeding.
All ages: Persistent asthma, socioeconomic vulnerability, immunodeficiency, smoke exposure, daycare attendance, air pollutants, multiple births, malnutrition.
Others: Older adults with COPD or functional disability.

Hand hygiene (alcohol-based rubs preferred)
Avoid passive smoke
Isolation of proven/suspected cases
Palivizumab: Monoclonal antibody for high-risk infants (preterm ≤28+6wks, <12mo at RSV season, BPD, cardiac/pulmonary disease)
Nirsevimab: Long-acting mAb, approved for broader population (single injection before season; advantage over palivizumab)
Breastfeeding: Reduces hospitalizations
Probiotics: Experimental (promising in animal studies)
AAP Prophylaxis Indications: Chronic lung disease, hemodynamically significant CHD, congenital airway/neuromuscular disease (<24mo); preterm <29wk and <1yr at season start
Dosage: Up to 5 monthly doses of palivizumab at 15 mg/kg IM

Pulmonary infiltrates/atelectasis, otitis media, hyperinflation, respiratory failure, hyperkalemia, apnea, bacterial pneumonia

Risk: Prematurity, smoke, daycare, siblings, immunization, respiratory disease in family
Symptoms (children): Nasal congestion, cough, coryza, low-grade fever, wheeze, nasal flaring, chest retraction
Symptoms (adults): URI, mild fever, cough, wheeze

Fever, tachypnea, grunting, flaring, retraction, apnea, hypoxia, dehydration, serous/acute otitis
URT: Rhinorrhea, congestion, cough, sneezing
LRT: Rhonchi, wheezing, crackles, prolonged expiration

Mild/URTI: Other viruses (parainfluenza, metapneumovirus, influenza, rhinovirus, coronavirus, adenovirus, bocavirus), allergic rhinitis, asthma, croup
Severe/LRTI: Bronchiolitis, asthma, pneumonia, foreign body

Clinical diagnosis; no routine confirmation required.
CXR: Hyperinflation, peribronchiolar thickening, atelectasis, infiltrates (if obtained)
PCR/Antigen: Used in hospitalized/high-risk patients only
Criteria for hospitalization: Apnea, hypoxia, respiratory failure, poor oral intake, dehydration, SpO₂ ≤92%

Supportive: Nasal suction, antipyretics, treat dehydration (oral/IV/NG fluids), oxygen (SpO₂ <92%)
Monitor for: Feeding, fluid status, respiratory distress

First line: Oxygen (if hypoxic), acetaminophen/ibuprofen for fever/pain, fluids for dehydration.
Not recommended: Albuterol/epinephrine, systemic steroids, hypertonic saline, routine antibiotics, chest physiotherapy.
Fluids: NG/IV if unable to feed orally.
Ribavirin: Only in select immunocompromised/LRTI cases.
Suction: May be used but excessive suctioning may prolong hospitalization.

Vaccine: Ad26.RSV.preF, RSVpreF (bivalent) for adults ≥60 yrs (CDC: one dose)
Maternal vaccination: RSVpreF vaccine during 32–36 wks gestation in RSV season
Monitor: Fluid/O₂, feeding status

<1% mortality (<400 deaths/year US)
Increased risk of recurrent wheezing, allergic sensitization, reduced pulmonary function, asthma