RESPIRATORY SYNCYTIAL VIRUS INFECTION (RSV)
RSV is one of the most common respiratory viruses in circulation. Older adults and infants are at greater risk for its development and for experiencing serious disease. Fortunately, both of these groups can now be protected from the disease via vaccination.
RSV causes annual outbreaks of respiratory illnesses in all age groups. In most regions of the United States, RSV season begins in the fall and peaks in the winter. The timing and severity of the RSV season can vary from year to year (CDC, 2023e).
Older adults, especially those with underlying health conditions (e.g., cardiac or respiratory disease), are at high risk for severe disease caused by RSV. RSV leads to about 60,000–120,000 hospitalizations and 6,000–10,000 deaths among adults 65 years of age and older on an annual basis (FDA, 2023a).
2023–2024 RSV Vaccine Updates
Several new RSV vaccines were approved by the U.S. Food and Drug Administration (FDA) in 2023:
- In May, the FDA approved Arexvy, the first RSV vaccine approved for use in the United States. Arexvy is approved for the prevention of lower respiratory tract disease (LRTD) caused by RSV in individuals ages 60 years and older (FDA, 2023a).
- In July, the FDA approved nirsevimab (Beyfortus) for the prevention of RSV in neonates and infants born during or entering their first RSV season and in children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season.
- In August, the FDA approved Abrysvo, the first vaccine for use in pregnant individuals to prevent LRTD and severe LRTD caused by RSV in infants from birth through age 6 months (FDA, 2023d).
AREXVY FOR ADULTS AGES 60 AND OLDER
The safety and effectiveness of the new respiratory syncytial virus (RSV) vaccine Arexvy is based on the FDA’s analysis of data from an ongoing, randomized, placebo-controlled clinical study conducted in the United States and internationally in 12,500 individuals ages 60 years and older. The main clinical study of Arexvy was designed to assess the safety and effectiveness of a single dose. Participants will remain in the study through three RSV seasons to assess the duration of effectiveness and the safety and effectiveness of repeat vaccination. Data for a single dose of Arexvy from the first RSV season of the study were available for the FDA’s analysis (FDA, 2023a).
Arexvy is not a live vaccine. It is a recombinant subunit vaccine that does not contain any living virus. Arexvy is generally well tolerated. Side effects are typically temporary and of brief duration. The most commonly reported side effects include:
- Injection site pain
- Fatigue
- Muscle aches
- Headache
- Joint pain
(Mayo Clinic, 2023)
Just one injection of Arexvy into the deltoid muscle is needed to provide protection against infection. It is safe to receive the RSV vaccine and the flu vaccine at the same time. It is not known if Arexvy will need to be administered annually. RSV does not mutate in the same ways as influenza and SARS-CoV-2, so it is believed, at this time, that there is not a need to be vaccinated annually. However, more research is needed. Clinical trial results showed that the vaccine provides protection for two RSV seasons, so it may ultimately need to be given every two years (CDC, 2023m).
The CDC recommends that adults 60 and older may receive the vaccine, using shared clinical decision-making. The decision to vaccinate an individual patient should be based on a discussion between the healthcare provider and the patient (CDC, 2023e).
NIRSEVIMAB (BEYFORTUS) FOR NEONATES AND CHILDREN UNDER AGE 2
In July 2023, the FDA approved nirsevimab, a long-acting monoclonal antibody, for passive immunization to prevent RSV-associated lower respiratory tract infection among infants and young children. In August, ACIP recommended nirsevimab for all infants ages <8 months who are born during or entering their first RSV season and for infants and children ages 8–19 months who are at increased risk for severe RSV disease and are entering their second RSV season.
On the basis of pre–COVID-19 pandemic patterns, nirsevimab could be administered in most of the continental United States from October through the end of March. Nirsevimab can prevent severe RSV disease among infants and young children at increased risk for severe RSV disease (FDA, 2023b; CDC, 2023l).
The most common side effects include rash and pain, swelling, or hardness at the injection site. Other possible side effects include:
- Swelling of the face, mouth, or tongue
- Respiratory distress
- Difficulty swallowing
- Unresponsiveness
- Cyanosis of the skin, lips, or underneath the fingernails
- Muscle weakness
- Severe rash, hives, or itching
(McGovern, 2023)
Nirsevimab comes with warnings and precautions about serious hypersensitivity reactions, including anaphylaxis, that have been observed with other human IgG1 monoclonal antibodies. The vaccine should be given with caution to infants and children with clinically significant bleeding disorders (FDA, 2023b).
ABRYSVO FOR PREGNANT INDIVIDUALS
The new RSV vaccine Abrysvo is the first vaccine approved for use in pregnant individuals to prevent lower respiratory tract disease (LRTD) caused by RSV in infants. According to the CDC, RSV is the leading cause of infant hospitalization in the United States. Abrysvo is approved for use at 32–36 weeks gestational age of pregnancy. It is a single-dose injection.
In studies, the most commonly reported side effects were pain at the injection site, headache, muscle pain, and nausea. Uncommonly, pre-eclampsia occurred in 1.8% of pregnant individuals who received Abrysvo compared to 1.4% of pregnant individuals who received a placebo. In safety studies, low birth weight and jaundice in infants occurred at a higher rate in pregnant Abrysvo recipients compared to pregnant placebo recipients( FDA, 2023d).
Impact of RSV Vaccination on General Health
RSV vaccination offers protection from RSV. This is especially important for older adults and infants who may get quite sick from the infection, need hospitalization, or even die (CDC, 2023f). Clinical studies of the new RSV vaccinations found:
- In infants born to pregnant individuals who received Abrysvo as compared to pregnant individuals who received placebo, Abrysvo reduced the risk of severe lower respiratory tract disease by 81.8% within 90 days after birth and 69.4% within 180 days after birth (FDA, 2023d).
- Of the 1,453 preterm infants who were born during or entering their first RSV season, 969 received a single dose of nirsevimab, and 484 received a placebo. Among infants who received the drug, 2.6% experienced RSV LRTI compared to 9.5% of infants who received a placebo. The drug reduced disease risk by about 75% relative to the placebo (FDA, 2023b).
- In a study of approximately 25,000 individuals 60 years of age and older in the United States and internationally, those who received Arexvy showed a reduced risk of developing RSV-associated LRTD by 82.6% and reduced risk of developing severe RSV-associated LRTD by 94.1% (FDA, 2023a).