Symptoms, complications, prevention, and vaccination guidance.
What is RSV? Understanding Respiratory Syncytial Virus Respiratory Syncytial Virus (RSV) is a common contagious virus that infects the lungs and breathing passages. Almost all children contract RSV by age 2, making it one of the most frequent causes of lower respiratory tract infections in infants and young children worldwide. Key Facts About RSV: Causative Agent: Single-stranded, negative-sense RNA virus Transmission: Droplet transmission through coughing, sneezing, or direct contact with contaminated surfaces Incubation Period: 2-8 days (average 4-5 days) Seasonality: Primarily occurs in fall and winter months in temperate climates Peak Incidence: Children under 2 years of age Global Burden: Over 30 million cases annually in children under 5 years; approximately 45,000 deaths in low- and middle-income countries 2. Why Infants Are at Higher Risk Infants and young children are particularly vulnerable to severe RSV disease due to developmental and immunological factors. Risk Factors for Severe RSV in Infants: Risk FactorDetailsAgeHighest risk in infants < 6 months; especially critical at < 3 monthsPrematurityBorn before 29 weeks gestation; immature immune systemChronic Lung DiseaseBronchopulmonary dysplasia (BPD) dramatically increases severityCongenital Heart DiseaseParticularly cyanotic heart diseaseImmunodeficiencyPrimary or secondary immunocompromised statesNeuromuscular DisordersDifficulty clearing secretions; increased aspiration riskDown SyndromeAssociated with more severe infectionsEnvironmental FactorsCrowded living conditions, air pollution, secondhand smokeBreastfeeding StatusLack of passive maternal antibodies increases riskDaycare/Sibling ExposureIncreased exposure to respiratory pathogens Research Finding: Hospitalization rates for RSV are 5-40 times higher in infants with chronic lung disease compared to healthy term infants (American Academy of Pediatrics, 2023). 3. RSV Symptoms and When to Seek Care RSV typically begins with upper respiratory symptoms before progressing to lower respiratory involvement. Classic Symptom Progression in Infants: Early Signs (Days 1-3): Runny or stuffy nose Sneezing Cough Low-grade fever (not always present in very young infants) Decreased appetite or difficulty feeding Irritability or lethargy Progressive Signs (Days 3-7): Increased cough, often with wheezing or whistling sound Rapid, labored breathing Retractions (skin pulling in around ribs and neck) Flaring of nostrils with each breath Grunting with respirations Poor feeding; dehydration risk Severe Symptoms Requiring Emergency Care: Seek immediate medical attention if your infant shows: Severe respiratory distress (marked retractions, grunting, nasal flaring) Cyanosis (bluish discoloration of lips, mouth, or fingernails) Apnea (pauses in breathing) Inability to drink fluids; signs of dehydration Lethargy or unresponsiveness Oxygen saturation < 92% on room air Respiratory rate > 70 breaths per minute (in infants < 2 months)
Respisartoy Distress Respiratory Failure Death
New RSV Vaccine ABRYSVO vaccine Given to pregnant Ldaies in later part of pregnancy provides adequate immunity to the infants In 2023-2024, the FDA approved the first RSV vaccine for use in older adults (GSK's Arexvy for ages ≥60). While this doesn't directly prevent RSV in infants, it protects high-risk infants by reducing exposure from vaccinated caregivers. Recommendation: Older caregivers and grandparents in close contact with high-risk infants should consider RSV vaccination per CDC guidance. Monoclonal Antibody Prophylaxis - Nirsevimab (NEW 2024) Major Update: FDA expanded approval of nirsevimab (Beyfortus) for RSV prophylaxis in all infants during their first RSV season, with special emphasis on high-risk populations.
Nirsevimab Guidelines: Eligibility: All infants < 8 months of age at the start of RSV season (July 1 - June 30) Premature infants (≤29 weeks gestation) up to 12 months during first RSV season Children 12-24 months with chronic lung disease or congenital heart disease Immunocompromised children up to 24 months Dosing: Single dose: 100 mg IM (< 5 kg) or 200 mg IM (≥ 5 kg) Administered during RSV season Can be given alongside routine vaccinations at different anatomical sites Efficacy: 75-80% reduction in RSV-caused lower respiratory tract disease requiring hospitalization Well-tolerated with minimal adverse effects Creates immediate, short-term immunity lasting RSV season Clinical Significance: Nirsevimab represents the first effective prevention strategy for all infants during RSV season, fundamentally changing preventive approach. Updated Palivizumab (Synagis) Recommendations Despite nirsevimab's introduction, palivizumab remains an option for selected high-risk populations: Current Indications: Premature infants (≤28 weeks gestation) during first RSV season Children with chronic lung disease requiring ongoing medical management Children with hemodynamically significant congenital heart disease Selected immunocompromised patients Dosing: 15 mg/kg IM monthly during RSV season (typically October-March in northern hemisphere)
By Dr. Salman Ahmad Bajwa, MBBS, DHPE | Vaccinology Consultant | Vaccine.pk
