Respiratory Syncytial Virus: A major cause of respiratory infections

Published Date : 11 December 2025

Posted by : Radhika Pawar

Respiratory illnesses are one of the top causes for hospital visits, mostly during the winter months. One virus that has received notable public health attention in recent years is the Respiratory Syncytial Virus (RSV). While RSV often resembles a common cold in healthy individuals, it can be a life-threatening case for infants, older adults, and people with chronic conditions. This blog covers an overview of RSV, its symptoms, how it spreads, who is at risk, and the latest prevention and treatment available. 

What is RSV? 

Respiratory Syncytial Virus is a common respiratory virus that infects the nose, throat, and lungs. Most people experience mild, cold-like illness, but RSV can cause severe lower respiratory tract disease, including bronchiolitis and pneumonia, especially in infants, older adults, and people with chronic conditions. Globally, RSV is one of the leading causes of acute lower respiratory infection in children and also contributes a substantial disease burden in older adults. Each year, RSV drives over 3.6 million hospitalizations and around 100,000 deaths in children under five, with the majority of pediatric deaths occurring in low- and middle-income countries. 

How RSV Spreads 

RSV spreads through respiratory droplets when an infected person coughs or sneezes, by close contact, e.g., kissing a child’s face, and by touching contaminated surfaces and then the eyes, nose, or mouth. RSV can survive for hours on hard surfaces, which is why hand hygiene and surface disinfection are key preventive steps. 

Symptoms to Watch 

Symptoms typically appear 4–6 days after exposure and often start like a cold: 

• Runny nose, cough, sneezing 

• Low-grade fever 

• Decreased appetite 

• Wheezing or rapid breathing is more common in infants 

Seek urgent care for signs of respiratory distress fast or labored breathing, chest retractions, blue lips/face, dehydration, or if symptoms worsen in high-risk groups such as young infants, older adults, and those with heart/lung disease or weakened immunity. 

Who Is at Highest Risk? 

• Infants especially <6 months and premature babies 

• Children with chronic lung or heart disease 

• Older adults and the risk rises with age 

• Anyone with underlying conditions (e.g., COPD, asthma, heart disease, diabetes) or weakened immunity 

These groups are more likely to develop LRTD, need hospitalization, or experience complications. 

RSV Seasonality and Disease Burden 

In many countries, RSV peaks during the cooler months, often from autumn to spring. In the United States, the CDC uses nationwide hospitalization data to produce weekly, in-season estimates of RSV outpatient visits, hospitalizations, and deaths to help public health planning. These 2024–2025 estimates are continuously updated and underscore RSV’s significant annual toll. 

Available Vaccines

1. Vaccines For Older Adults 

In May 2023, the U.S. FDA approved Arexvy (GSK), the first RSV vaccine for adults aged 60+. As of August 2025, Arexvy’s U.S. label also includes adults 50–59 at increased risk for RSV LRTD. The CDC currently recommends a single dose, not an annual series, for adults 75+ and for adults 50–74 with increased risk. Discuss eligibility and timing with a clinician before the RSV season.  

2. Maternal Vaccination to Protect Newborns 

A maternal RSV vaccine (Pfizer’s Abrysvo) can be given during 32–36 weeks of pregnancy, timed to the local RSV season, to pass protective antibodies to the baby before birth. In the U.S., CDC highlights September–January for most regions (timing varies by location). Protection for the infant begins around two weeks after maternal vaccination. 

3.Long-Acting Monoclonal Antibody 

In July 2023, the FDA approved nirsevimab (Beyfortus), a single-dose antibody that directly protects infants from RSV. It is recommended for infants younger than 8 months entering their first RSV season, particularly if the mother did not receive maternal RSV vaccination, and for certain high-risk children up to 24 months entering a second season. Public health authorities update supply and eligibility guidance seasonally. 

Impact of RSV in Older Adults 

While RSV has traditionally been seen as a childhood illness, research now shows that RSV is also a major health threat to older adults. In the U.S., RSV is expected to cause tens of thousands of hospitalizations and several thousand deaths among people over 65 years of age every year. This has led to a high focus on adult vaccination programs, particularly in nursing homes and long-term care facilities. RSV can lead to pneumonia and exacerbations of chronic conditions, e.g., COPD, heart failure in older adults. 

What Parents and Caregivers Should Know 

• Newborn protection: If you’re pregnant during RSV season, ask about maternal RSV vaccination to protect your baby from birth. If maternal vaccination wasn’t received or delivery occurred within 14 days of vaccination, ask your pediatric provider about nirsevimab for your newborn. 

• Second season risks: Some children with chronic lung or heart disease or severe prematurity may qualify for nirsevimab in their second RSV season; confirm eligibility locally. 

• Hygiene still matters: Handwashing and limiting exposure to sick contacts remain important, especially for infants in the first months of life.