Respiratory Syncytial Virus (RSV) is a common respiratory virus that infects the lungs and breathing passages. While it often causes mild, cold-like symptoms in older children and adults, RSV can lead to serious illness in infants. Understanding RSV’s impact, risk factors, and protective measures is important for safeguarding infant health and recognizing signs of severe infection.
Understanding RSV’s Impact on Infants
RSV poses a significant threat to infants globally, frequently leading to hospitalizations and, in severe cases, death. Each year, over 3 million children under five years old are hospitalized worldwide due to RSV, with more than 100,000 of these cases resulting in death. The vast majority, approximately 99%, of these fatalities occur in low- and middle-income nations. In the United States, RSV accounts for an estimated 58,000 to 80,000 hospitalizations and around 250 infant deaths annually.
RSV is particularly dangerous for infants due to their small, developing airways and immature immune systems. The virus can spread to the lower respiratory tract, causing inflammation of the small airways (bronchiolitis) or lung infection (pneumonia). These conditions make breathing difficult, often leading to rapid, shallow breathing, wheezing, and a bluish tint to the skin due to lack of oxygen. Very young infants may also experience irritability, decreased activity, poor feeding, and even pauses in breathing, known as apnea.
Hospitalization is often necessary for infants with severe RSV, requiring supportive care like oxygen therapy, intravenous fluids, or mechanical ventilation. Approximately two to three out of every 100 infants under six months are hospitalized annually.
Factors Increasing Risk for Severe RSV
Certain characteristics and existing health conditions make infants more susceptible to severe RSV infections and adverse outcomes. Premature infants face a higher risk of severe disease, hospitalization, and even death, with studies indicating they are three times more likely to die from RSV than full-term babies. Their underdeveloped lungs and lower levels of protective maternal antibodies contribute to this increased vulnerability.
Infants with chronic lung diseases, like bronchopulmonary dysplasia, are at higher risk. These conditions compromise lung function, hindering secretion clearance and infection fighting. Babies with congenital heart disease are also more prone to severe RSV and complications, as altered blood flow and increased lung pressure worsen viral effects.
A weakened immune system, from medical conditions or treatments, makes infants less able to fight the virus. Neuromuscular disorders affecting breathing or swallowing also increase severe RSV risk by impairing mucus clearance and airway maintenance. Infants under six months are at highest risk for severe outcomes, regardless of other conditions.
Environmental factors also increase risk. Secondhand smoke or indoor air pollution can irritate the respiratory system, increasing susceptibility to severe infection. Crowded living conditions, daycare attendance, or school-aged siblings also increase viral exposure and severe illness risk.
Protecting Infants from Severe RSV
Protecting infants from severe RSV involves a combination of preventive strategies and timely medical management. Immunization protects against severe RSV. A maternal RSV vaccine, like Abrysvo, given to pregnant individuals between 32 and 36 weeks of gestation, passes antibodies to the baby through the placenta, providing protection for up to six months. This vaccination reduces severe RSV risk in infants by 69% to 81.8%.
A second option is nirsevimab (Beyfortus), a monoclonal antibody injection given directly to infants. This single shot provides immediate passive immunity for five to six months. It is recommended for all infants under eight months whose mothers did not receive the RSV vaccine, and for certain high-risk infants up to 24 months. Clinical trials show nirsevimab reduces severe RSV requiring medical attention or hospitalization by 74.5% to 82.7%.
Beyond immunizations, good hygiene is protective. Frequent handwashing, especially before touching an infant, and regularly cleaning surfaces and toys prevent virus spread. Avoiding contact with sick individuals and limiting crowded environments during RSV season are important, particularly for high-risk babies. A smoke-free environment reduces an infant’s severe RSV risk.
Early symptom recognition and prompt medical attention manage the infection. Parents should seek immediate medical care if an infant exhibits difficulty breathing, high fever, bluish lips or nail beds, breathing pauses, or significant changes in feeding or activity. Supportive care, including oxygen therapy and intravenous fluids, helps infants recover from severe RSV. Breastfeeding also provides antibodies that protect babies from RSV and other infections.