The Food and Drug Administration has approved the first vaccine to protect older adults from the respiratory syncytial virus, also known as RSV. This virus can be fatal, and it is associated with at least 60,000 hospitalizations and 6,000 to 10,000 deaths annually in adults 65 and older in the U.S.

The virus is also a leading cause of death for children globally. GSK’s vaccine, called Arexvy, appears to be effective in preventing lower respiratory tract illnesses caused by RSV.

What is RSV?

Respiratory syncytial virus (RSV) is a common virus that can cause mild cold-like symptoms in adults and older children. However, it can be more severe in infants, young children, older adults, and people with weakened immune systems.

In any given year, RSV is the single most common reason young children are admitted to most U.S. children’s hospitals, even more common than flu. But for some reason, most people have never heard of it.

RSV is highly contagious and spreads through respiratory secretions like mucus or saliva, especially when an infected person coughs or sneezes. It can also survive on surfaces for several hours, making it easy to pick up from contaminated objects.

In infants, RSV can cause bronchiolitis, a condition that affects the small airways in the lungs, making it difficult to breathe. This can lead to wheezing, rapid breathing, and coughing. Infants with severe cases may require hospitalization and supportive care such as oxygen therapy and intravenous fluids.

For older adults and people with weakened immune systems, RSV can cause pneumonia or exacerbate existing respiratory conditions like asthma or chronic obstructive pulmonary disease (COPD). In severe cases, RSV can lead to respiratory failure and even death.

RSV occurs annually in the fall in temperate countries worldwide.

Why a vaccine matters: RSV can be lethal

RSV is particularly dangerous for older adults, especially those with underlying health conditions, such as heart or lung disease or weakened immune systems. Pneumonia, often caused by the virus, is particularly worrisome for the elderly.

To make matters more complicated, this winter, RSV contributed to the “tripledemic,” along with flu and Covid, that overwhelmed children’s hospitals and some I.C.U. wards.

The newly approved GSK vaccine was nearly 83 percent effective in preventing lower respiratory tract illness in adults 60 and older in a study of about 25,000 patients, according to data published in The New England Journal of Medicine. Pfizer’s RSV vaccine for older adults is also expected to receive F.D.A. approval this month.

The FDA advisers did learn of some rare side effects from the vaccine trials. In the days after the shots were given, two recipients of the Pfizer vaccine and one recipient of the GSK shot developed cases of Guillain-Barré, a condition where the immune system attacks the nervous system. More than 12,000 participants received the vaccine in the last trial.

Once the shots become available to the public, the agency said it would require GSK to monitor the incidence of Guillain-Barré and another rare condition that was possibly related to the shot.

However, it will still be months before the adult vaccine is publicly available in the United States. The Centers for Disease Control and Prevention is expected to follow the FDA’s approval, most likely issuing its recommendation in June. GSK said its vaccine would then be available in the fall at U.S. pharmacies, clinics, and other healthcare settings.

For Medicare patients with Part D drug coverage, there would be no out-of-pocket expense. The company has not released a price, although insurers typically cover much of the cost of many vaccines.

Along with GSK and Pfizer, Moderna is also developing an RSV vaccine for this age group and said it expected authorization in the first half of this year. AstraZeneca and Sanofi are seeking FDA approval for a monoclonal antibody treatment to protect infants and toddlers up to 2 years old from RSV infections. Pfizer has applied for separate approval of an RSV vaccine to be given in the later stages of pregnancy to protect young infants.

GSK’s Arexvy vaccine is a significant milestone in the fight against RSV, which can be lethal for older adults. The availability of vaccines for RSV in other vulnerable demographics, such as infants and pregnant women, is also welcomed. The ultimate goal is to eradicate this deadly virus that claims so many lives each year.

In the meantime, the best way to prevent the spread of RSV is to:

• wash your hands frequently.
• avoid close contact with sick people.
• cover your mouth and nose when coughing or sneezing.

If you or a loved one experience symptoms of RSV, such as cough, fever, or difficulty breathing, it is important to seek medical attention, especially if you are at high risk for severe disease. Early diagnosis and treatment can help prevent complications and improve outcomes.