Q&A: Respiratory Syncytial Virus

Yale pulmonologist Denyse Lutchmansingh, MD, talks RSV vaccine recommendations and efficacy, prevention, risks, disease burden, and treatment.

Dr Lutchmansingh, thank you for joining us today. Would you please introduce yourself?

I'm Denyse Lutchmansingh, MD. I'm an assistant professor of medicine at Yale University and a pulmonary/critical care doctor as well as associate director of the Winchester Center for Lung Disease. My expertise evolved from purely general pulmonary medicine into an interest in post-acute sequelae of COVID-19 and its impact on patients during the pandemic. My interest in virus prevention stems not only from my pulmonary background but also from having seen complications related to viral infections.

Would you please explain what you recommend regarding the RSV vaccine?

We follow the Centers for Disease Control and Prevention (CDC) guidelines, which is that anyone above the age of 60 years with high-risk conditions will qualify for RSV vaccination. That includes people with chronic lung disease or cardiac disease, for example.

Here are the CDC recommendations^[1] for who should get the RSV vaccine and details about recommendations:

Adults aged 60 years or older
- Adults 60 and older should receive a single dose of RSV vaccine.
Infants and young children
- To help prevent severe RSV in infants, the CDC recommends that the mother receives the RSV vaccine during pregnancy, or the infant receives immunization with the RSV monoclonal antibody.
Pregnant people
- Pregnant people should receive the RSV vaccine between 32 and 36 weeks of pregnancy, administered between September and January. The only vaccine recommended during pregnancy is Abrysvo.
Infants and young children
- Infants 8 months and younger who are born during or are entering their first RSV season should receive one dose of nirsevimab.
- Infants and children aged 8-19 months who are at risk of severe RSV and who are entering their second RSV season should receive one dose of nirsevimab.

There are additional details on the CDC's website^[2] that I recommend checking out.

How long are people with RSV contagious? And do you recommend any sort of isolation for people with a positive RSV test or suspected RSV?

People infected with RSV are usually contagious for 3-8 days and may become contagious a day or 2 before they start showing signs of illness. However, some infants and people with weakened immune systems can continue to spread the virus even after they stop showing symptoms for as long as 4 weeks.^[3]

The R0 factor is often used to discuss virus transmission and represents how many people can be infected by one person. We do not utilize this much clinically, but RSV is known to be fairly contagious.

Regarding isolation, the CDC does not require isolation for adults infected with RSV.^[4]

What do you recommend for RSV prevention other than vaccination?

This is similar to preventative measures for any type of viral infection: (1) avoid sick contacts whenever possible and (2) frequent hand washing.^[5] I also still recommend masking for patients. Prior to the pandemic, we actually recommended masking for some of our high-risk patients, particularly when they traveled on airplanes or trains or in any high-risk situation such as crowded areas. I do still recommend the same measures for RSV prevention, but the final decision is up to the individual.

With symptoms of RSV being similar to the common cold, COVID-19, and influenza in many patients, when do you recommend that clinicians test for RSV?

I traditionally think about testing in terms of what is going to be the actionable item after testing or what is the potential intervention. I do think high-risk populations should be tested, for example, patients with lung disease. We know they are more vulnerable, and they need to be monitored more closely. In Connecticut, we do have combined COVID-19, influenza, and RSV polymerase chain reaction (PCR) testing available in the outpatient setting. Because RSV can mimic any one of these, we will swab and complete testing for all three.

For RSV, is there an antigen test? Or is it always PCR?

PCR testing is the standard for us, as it's more reliable than antigen testing and is considered the gold standard.^[6] In younger patients (< 20 years), RSV can also be diagnosed by antigen detection.

What are the treatment recommendations for patients with RSV who are not at elevated risk?

For most patients, management is supportive care, such as rest, hydration, and antipyretics for fever. Patients with preexisting lung disease may need to use their bronchodilator medications (inhalers) more frequently. It's important to remember that if patients do have preexisting lung disease, an RSV infection can exacerbate this, so sometimes, they may need treatment with steroids too.^[7]

What are treatment recommendations for those who are high risk?

Antiviral treatments are specifically reserved for adult patients who are immunocompromised or patients with a history of transplant, and this treatment is determined on a case-by-case basis. Ribavirin combined with intravenous immunoglobulins have been used in high-risk adult patients.^[8]

Hospitalization is usually reserved for patients who are experiencing significant symptoms or decreases in their oxygen levels, or they need some other sort of intervention. For example, if we think that they are having issues with their heart because of the RSV infection, they would need to be hospitalized.

What do you recommend to doctors regarding pulse oximetry numbers when an adult has RSV?

Pulse oximetry can be a useful monitoring tool. If you're a patient without chronic lung disease, you should be able to easily maintain an adequate (what we call) an SpO2, or oxygen level greater than 95%. So if an otherwise healthy patient's oxygen levels are at 90% or lower, that would be a reason to go to the emergency room for further evaluation.

However, patients with lung diseases sometimes have chronic oxygen needs. We would have to consider their baseline, ie, their normal oxygen levels and how much oxygen they're using to maintain their oxygen levels. If their oxygen levels are lower than baseline or they are requiring additional supplemental oxygen, they should seek medical attention.

Are you finding that patients who are suffering from long COVID are more at risk for severe RSV than are those who aren't?

Anecdotally, we haven't really experienced that post-COVID, patients seem to be more vulnerable to acquiring RSV or any other viral infection. However, there are two parts to that question. Are they more at risk for acquiring a viral infection? If they do get a viral infection, then do they have more severe symptoms? So far, our post-COVID patients have not experienced either one.

What can you tell us about co-infection of COVID-19 and RSV and how it could increase the risk for severe RSV?

Studies have shown increased risk for co-infection of RSV and COVID-19 among infants and children younger than 17 years,^[9] and this has been associated with severe illness. There are limited data in adults regarding co-infection risk, although RSV is the third most common cause of viral infections resulting in need for hospitalization. However, one study showed no significant increase in ICU admission and need for mechanical ventilator support in patients with SARS-CoV-2 co-infection with respiratory syncytial virus or adenoviruses.^[10]

What can you tell us about RSV vaccine efficacy?

Clinical trials demonstrated that the RSV vaccine prevented RSV-associated lower respiratory tract illness and RSV-associated acute respiratory illness in adults (≥ 60 years of age), without safety concerns.^[11]

Vaccine efficacy was greater than 80% against severe RSV-related lower respiratory tract disease and greater than 60% against RSV-related acute respiratory infection with similar efficacy against the RSV A and B subtypes. High vaccine efficacy was observed in multiple age groups and in participants with coexisting conditions.^[12]

What information do you recommend clinicians give to adults who are hesitant to get the RSV vaccine?

There is no current specific outpatient treatment for RSV in adults, so prevention is the best strategy. In addition, high-risk individuals have greater likelihood of hospitalization with RSV infections, particularly those with asthma, chronic obstructive pulmonary disease, ischemic heart disease, stroke, chronic kidney disease, and diabetes compared with the overall population.^[13] There have been reports of neurologic side effects associated with RSV vaccination including risk of Guillain-Barré, but this is rare.

What do you wish all primary care clinicians knew about RSV?

I think there's benefit in testing patients who are at high risk for complications related to RSV, just like you would for influenza or COVID-19. The argument has always been that there are treatment options for influenza and COVID-19 but not for RSV. However, RSV is among the most common viral infections associated with need for hospitalization in adults with viral illnesses. Between February 2022 and May 2023, hospitalizations for RSV were associated with more severe disease than was hospitalizations for COVID-19 or influenza.^[14] Therefore, it's important to think about testing in patients who are considered high risk so they are more aware of potential complications for themselves, and if they do need to seek a higher level of medical care, they're more inclined to do so sooner rather than later. Patient awareness is important. There's still power to that.

In your opinion, how is the conversation about RSV changing?

The conversation about RSV is changing now that there's a vaccine available. Traditionally, when people think about RSV, they think of it as mainly something that affects babies. So it's great that there is more conversation about the impact of RSV infection on adults. More primary care doctors are raising awareness in their patients and talking with them about prevention. Hopefully, there is an approved outpatient treatment or an intervention on the horizon in the next couple of years.

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