We have exciting news to share: For the very first time, we have a tool to prevent severe respiratory syncytial virus (RSV) in babies. Starting in October, newborns and infants can receive an injection right in Stamford Health’s newborn nursery to prevent severe illness. RSV, which typically appears in October or November and lasts until March, is a respiratory virus that usually causes mild, cold-like symptoms, but can be more serious in infants and older adults.

The new monoclonal antibody, nirsevimab, which is not a vaccine but free through our childhood vaccination program, is highly recommended for two age groups: newborns who are younger than 8 months and entering their first RSV season; and 8-19-month-olds who have certain chronic medical conditions and are entering their second RSV season.

Unlike a vaccine, the long-acting RSV monoclonal antibody does not introduce the virus into the body. Rather, it prevents the virus from entering the body’s cells. It renders immunity within about a week of administration and protects an infant for five months — about the length of an RSV season.

How effective is the RSV monoclonal antibody?

Clinical trials have found the injection to be safe and well-tolerated. The most common side effects included fever, rash, swelling or pain at the injection site, or diarrhea. There have been no reports of hypersensitivity or allergic reaction. Children who are allergic to any of the ingredients in the drug should not take it.

The shot is also highly effective. In clinical trials, one dose was about 80% effective at reducing the risk of severe disease requiring hospitalization, and 90% effective at preventing lower respiratory tract infections that required admission to an intensive care unit.

Why is RSV more harmful in infants?

RSV is so common that most children get it by the time they’re 2 years old. It is also highly contagious. It usually spreads through respiratory droplets that hang in the air after an infected person coughs or sneezes, or through direct contact with a contaminated surface.

Last year, we saw a surge in cases after two years of COVID-19 and social distancing had decreased population-based immunity. When masks came off, and kids returned to schools and daycares, people started getting infected.

Although most people recover within a week or two, RSV can be serious in infants and older adults. In the United States, it is the leading cause of hospitalization among infants. It can be particularly dangerous in the youngest babies — those under 8 months old – causing their tiny airways to swell and leading to a lower respiratory tract infection called bronchiolitis, which can impede breathing and require hospitalization. It can also be dangerous in older infants who have chronic lung or heart disease, or a compromised immune system.

Prematurity is a risk factor for RSV-associated hospitalization, too. Premature infants — those born at fewer than 30 weeks’ gestation — have a greater risk of RSV-associated hospitalization and ICU admission than infants born at term.

Even though the shot is not mandatory, the most highly respected medical organizations, including the American Academy of Pediatrics, strongly advise parents to add it to their babies’ vaccine schedule. It can be administered simultaneously with other childhood vaccines without interrupting their effectiveness.

RSV can be severe and scary, but now we have a new tool to help protect babies from it. Please talk with your child’s pediatrician about the shot and see if your child is eligible to receive it.