RSV vaccines: Questions patients may have and how to answer

In many parts of the country, the fall season of crisp, cool breezes and leaves changing colors is followed by a cold, snowy winter. But these seasons also bring with them respiratory syncytial virus (RSV), which can be serious for infants and older adults. And while there are RSV vaccines available, many require further guidance on what to do. 

RSV is a common respiratory virus that usually causes mild, cold-like symptoms with most people recovering in a week or two. However, RSV is one of the most common causes of hospitalization in infants and severe disease and hospitalizations in older adults, particularly those with chronic medical conditions.

According to data from the Centers for Disease Control and Prevention (CDC), RSV is responsible for 58,000–80,000 hospitalizations among children younger than 5 years old and 100,000–150,000 hospitalizations among adults 60 years or older each year.

Here are some questions patients might have about RSV vaccines, along with the answers that physicians should be ready to share.

The first vaccines for RSV were licensed by the Food and Drug Administration (FDA) in 2023 for older adults. There are now three RSV vaccines recommended for those 75 or older and for adults 60–74 years old who are at increased risk of severe RSV disease.

If you have already received an RSV vaccine, you do not need to get another one at this time. While you can get an RSV vaccine at any time, the best time to get vaccinated is in late summer and early fall.

RSV generally causes mild upper respiratory disease in healthy adults. But for adults 60 or older with certain underlying conditions or other risk factors, RSV can cause serious illness.

For example, those with chronic medical conditions such as lung diseases, cardiovascular diseases, neurologic or neuromuscular conditions, kidney disorders, liver disorders, diabetes or moderate or severe immune compromise are good candidates for RSV vaccination, according to the CDC.

Additionally, those who are of advanced age, reside in nursing homes or other long-term care facilities and have underlying medical conditions can also benefit from RSV vaccination.

For now, only one dose of the RSV vaccine is recommended. So far, RSV vaccines appear to provide some protection for at least two RSV seasons. Additional evaluation is planned to assess how long the protection lasts and whether additional doses will be needed.

Vaccination should occur before the onset of the fall and winter RSV season. The tricky part is that the typical RSV seasonality was disrupted by the COVID-19 pandemic. It has not returned to pre-pandemic patterns yet. For physicians recommending RSV vaccination based on shared clinical decision making, a vaccine should be administered as early as the supply becomes available, says the CDC.

Flu, COVID-19 and RSV vaccines may be given at the same visit. If patients prefer to receive each vaccine at a separate visit, there is no minimum waiting period between vaccines.

Patients receiving multiple vaccines during the same clinic visit may be more likely to experience common symptoms associated with vaccines, such as fever, headache and pain or swelling at the injection site(s).

As with other vaccines, patients can expect some side effects from RSV vaccination. Some of the common side effects include fatigue, fever, headache, muscle or joint pain, nausea and diarrhea. The side effects are typically mild, says the CDC.

A small number of participants in clinical trials developed serious neurologic conditions, including Guillain-Barré syndrome (GBS), after receiving GSK's Arexvy or Pfizer's Abrysvo. Available data support existence of an increased risk of GBS after RSV vaccination with both GSK’s Arexvy and Pfizer’s Abrysvo. 

However, there is still uncertainty in the amount of increased GBS risk with these vaccines. While there were no reports of GBS among adults who received Moderna's mResvia vaccine in clinical trials, a similar safety signal cannot be ruled out. CDC and FDA will continue to monitor RSV vaccine safety and share data as they become available.

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Two immunization products are available for the prevention of severe RSV disease in infants. The maternal RSV vaccine (Pfizer's Abrysvo) is given during weeks 32 through 36 of pregnancy during September through January in most of the U.S. Maternal antibodies protect the baby against RSV for approximately 6 months after birth. 

There is also  an immunization for babies called nirsevimab that can reduce the risk of RSV disease and hospitalizations in infants. Most infants will likely only need protection from either the maternal RSV vaccine or the RSV immunization—nirsevimab—for babies, and not both.

Nirsevimab is a single shot that is long lasting and can be given with other age-appropriate childhood vaccines. Studies have shown that protection from nirsevimab lasts for about five months. This is good because the typical RSV season lasts for four to five months.

The CDC recommends one dose of nirsevimab for all infants younger than 8 months, born during—or entering—their first RSV season, which is typically fall through spring. 

For a small group of children between 8 and 19 months old who are at increased risk of severe RSV disease—such as children who are severely immunocompromised—a dose is recommended in their second season. 

There is also a preventive medication available called palivizumab—marketed as Synagis. It is a monoclonal antibody that is given monthly to babies under 24 months old and is recommended only for infants with certain high-risk conditions. Only about 2–3% of infants typically receive one or more doses annually. If a child receives nirsevimab, they will not need additional doses of palivizumab during the current respiratory virus season. 

For children who are not eligible for the monoclonal antibody immunization, following proper infection prevention measures will be key. These are the same infection prevention measures that have been used to help stop the spread of other respiratory illnesses like COVID-19 and the flu.

This means kids should frequently wash their hands and avoid others who may be sick. The CDC also recommends that parents should wipe down any shared objects and toys with a disinfectant.

For infants born during or entering their very first RSV season, nirsevimab was 79% effective against RSV medically attended lower respiratory tract illness and 80% effective at preventing hospitalization.

Both vaccines for older adults are also extremely effective at preventing serious illness from RSV infection.

Most private health insurers must cover these immunization products without cost sharing. Medicare Part D covers all vaccines that the ACIP recommends, including vaccine for RSV.

Nirsevimab will be covered by Medicaid and the Children’s Health Insurance Program (CHIP) for kids. Most children enrolled in Medicaid are generally receiving nirsevimab doses through the Vaccines for Children (VFC) program. The maternal RSV vaccine will be included in the VFC program for pregnant people younger than 19.