RSV
A common respiratory virus that usually causes cold-like illness but can produce bronchiolitis, pneumonia, hospitalization, and death in infants and older or high-risk adults.
What causes RSV?
Respiratory syncytial virus spreads through respiratory droplets, close contact, and contaminated hands or surfaces when infected secretions reach the eyes, nose, or mouth.
Symptoms and what to notice
Runny nose, reduced appetite, cough, sneezing, fever, and wheezing. Very young infants may show irritability, decreased activity, feeding difficulty, or pauses in breathing rather than typical cold symptoms.
How long can it last?
Symptoms usually appear 4 to 6 days after infection and often improve within 1 to 2 weeks, though cough or wheeze can last longer. Reinfections occur throughout life.
How serious is RSV?
RSV is a leading cause of infant hospitalization and can cause bronchiolitis or pneumonia. Older adults and people with chronic heart, lung, or immune conditions can develop respiratory failure or worsening of underlying disease.
Treatment and management
Most cases need fluids, nasal suction, fever care, and monitoring. Hospital treatment may include oxygen, hydration, or respiratory support. Antibiotics do not treat RSV, and routine bronchodilators, steroids, or antivirals are not indicated for most infants.
Vaccine: who and when?
Adult vaccines are Arexvy, Abrysvo, and mRESVIA. CDC recommends one dose for all adults 75 or older and adults 50-74 at increased risk. Abrysvo is the maternal vaccine given at 32-36 weeks during the seasonal window. Infants are protected by maternal Abrysvo or a long-acting antibody—Beyfortus (nirsevimab) or Enflonsia (clesrovimab)—not by an infant vaccine.
Cost note: Patient cost varies by product, provider, insurance, location, and eligibility. Many recommended vaccines are covered in network without cost sharing, and qualifying children may use the Vaccines for Children program.
Trusted source
Patient cost varies by insurance, provider, location, and eligibility. Coverage and public-health access differ, so listed prices are examples rather than guaranteed patient prices. This page is for general education and does not replace individualized medical advice, diagnosis, vaccination assessment, or treatment.
RSV: Symptoms, Causes, Treatment, Prevention, and Vaccine Information
Nearly every child is infected with RSV by age two, but risk is not equal. Premature infants, babies in their first season, some young children with major conditions, and older adults can develop severe lower-respiratory disease. Prevention now includes adult vaccines, one maternal vaccine, and long-acting monoclonal antibodies for infants.
Important: This page is for general education. It does not replace diagnosis, treatment, vaccination advice, or emergency care from a qualified healthcare professional.
Quick Facts
| Topic | Current information |
|---|---|
| Cause | Respiratory syncytial virus spreads through respiratory droplets, close contact, and contaminated hands or surfaces when infected secretions reach the eyes, nose, or mouth. |
| Main symptoms | Runny nose, reduced appetite, cough, sneezing, fever, and wheezing. Very young infants may show irritability, decreased activity, feeding difficulty, or pauses in breathing rather than typical cold symptoms. |
| Typical course | Symptoms usually appear 4 to 6 days after infection and often improve within 1 to 2 weeks, though cough or wheeze can last longer. Reinfections occur throughout life. |
| Treatment | Most cases need fluids, nasal suction, fever care, and monitoring. Hospital treatment may include oxygen, hydration, or respiratory support. Antibiotics do not treat RSV, and routine bronchodilators, steroids, or antivirals are not indicated for most infants. |
| Vaccine status | Adult vaccines are Arexvy, Abrysvo, and mRESVIA. CDC recommends one dose for all adults 75 or older and adults 50-74 at increased risk. Abrysvo is the maternal vaccine given at 32-36 weeks during the seasonal window. Infants are protected by maternal Abrysvo or a long-acting antibody—Beyfortus (nirsevimab) or Enflonsia (clesrovimab)—not by an infant vaccine. |
History and Public-Health Importance
RSV was identified in the 1950s. A failed formalin-inactivated vaccine trial in the 1960s caused enhanced illness and delayed progress for decades. Structural understanding of the prefusion F protein led to successful vaccines and antibodies. Arexvy and Abrysvo were approved in 2023, mRESVIA followed, nirsevimab transformed infant prevention, and clesrovimab added another first-season antibody option.
What Causes RSV?
Respiratory syncytial virus spreads through respiratory droplets, close contact, and contaminated hands or surfaces when infected secretions reach the eyes, nose, or mouth.
Virus reaches mucous membranes through droplets, direct contact, or contaminated surfaces. Children can carry RSV into households and care facilities. People may spread virus for days, while infants and immunocompromised patients can shed longer. Reinfection is common because immunity is incomplete and decreases over time.
Symptoms and Typical Course
Runny nose, reduced appetite, cough, sneezing, fever, and wheezing. Very young infants may show irritability, decreased activity, feeding difficulty, or pauses in breathing rather than typical cold symptoms.
Illness often begins as a cold and moves to cough or wheezing. Bronchiolitis in infants can cause rapid breathing, chest retractions, poor feeding, and apnea. Older adults may have pneumonia or worsening heart failure, asthma, or COPD. Recovery is usually complete but cough can persist.
Complications and Who Is at Higher Risk
RSV is a leading cause of infant hospitalization and can cause bronchiolitis or pneumonia. Older adults and people with chronic heart, lung, or immune conditions can develop respiratory failure or worsening of underlying disease.
Infants may develop dehydration, low oxygen, apnea, or respiratory failure. Older adults can have bacterial coinfection, cardiovascular stress, functional decline, hospitalization, or death. Prematurity, chronic lung or congenital heart disease, cystic fibrosis, severe immune compromise, and advanced age increase risk.
How It Is Diagnosed
RSV can be diagnosed clinically or confirmed with antigen or molecular testing. Testing is more common in hospitalized or high-risk patients and during outbreaks. A positive result does not exclude another respiratory infection, and treatment decisions depend on severity rather than the test alone.
Treatment and Recovery
Most cases need fluids, nasal suction, fever care, and monitoring. Hospital treatment may include oxygen, hydration, or respiratory support. Antibiotics do not treat RSV, and routine bronchodilators, steroids, or antivirals are not indicated for most infants.
Supportive care is central. Infants may need nasal suction, supplemental oxygen, feeding support, or intravenous fluids. Mechanical ventilation is occasionally required. Ribavirin is reserved for exceptional circumstances. Clinicians evaluate for bacterial infection when findings warrant antibiotics rather than prescribing them routinely.
Vaccine Information
Adult vaccines are Arexvy, Abrysvo, and mRESVIA. CDC recommends one dose for all adults 75 or older and adults 50-74 at increased risk. Abrysvo is the maternal vaccine given at 32-36 weeks during the seasonal window. Infants are protected by maternal Abrysvo or a long-acting antibody—Beyfortus (nirsevimab) or Enflonsia (clesrovimab)—not by an infant vaccine.
Arexvy is an adjuvanted protein vaccine, Abrysvo is a bivalent prefusion F vaccine, and mRESVIA is an mRNA vaccine for adults. RSV vaccination is currently a single dose, not annual, unless guidance changes. Only Abrysvo is used in pregnancy. Nirsevimab and clesrovimab are antibodies rather than vaccines; most infants need either maternal vaccination or an infant antibody, not both, except in special circumstances.
Prevention
Use the recommended adult or maternal vaccine and infant antibody strategy, wash hands, improve ventilation, clean shared surfaces, avoid kissing infants when ill, and keep high-risk people away from sick contacts when possible. Healthcare and childcare facilities should follow respiratory precautions during outbreaks.
When to Seek Medical Care
Seek urgent care for pauses in breathing, blue lips, severe chest retractions, inability to feed, dehydration, confusion, worsening shortness of breath, or symptoms in a very young or medically fragile infant.
Frequently Asked Questions
Are nirsevimab and clesrovimab vaccines?
No. Beyfortus and Enflonsia are long-acting monoclonal antibodies that provide immediate seasonal protection.
Which RSV vaccine is used during pregnancy?
Only Pfizer’s Abrysvo is recommended for maternal vaccination at 32-36 weeks during the seasonal window.
Do adults need RSV vaccine every year?
No. Current CDC guidance recommends one dose for eligible adults, not annual vaccination.
Can antibiotics treat RSV?
No. Antibiotics treat bacterial coinfection, not RSV itself.
Key Takeaway
RSV is usually mild but can be dangerous at the extremes of age. Adult vaccines, maternal Abrysvo, and infant antibodies now prevent many severe cases when used for the right population.
Medical, treatment, and vaccine information was reviewed against official U.S. public-health guidance available through September 2026.