Adult RSV: Q&A With the CDC's Michael Melgar, MD

Over the past few years, COVID-19 has overshadowed seasonal respiratory diseases like respiratory syncytial virus (RSV) infection. But this year, early surges in RSV across the United States have spurred public attention. Though the infection is a common cause of respiratory disease, it is often overlooked in adults, said Michael Melgar, MD, a medical officer with the Centers for Disease Control and Prevention (CDC) National Center for Immunization and Respiratory Diseases. Medscape Medical News spoke with Melgar to answer questions about adult RSV, developing vaccines, and how to prepare for co-circulation of COVID-19, RSV, and influenza this winter.

What do primary care providers need to know about RSV?

Clinicians should be aware of increases in respiratory viruses, including RSV. CDC surveillance is currently showing an increase in RSV detections and RSV-associated emergency department visits and hospitalizations in multiple regions of the United States. While RSV activity normally peaks in December or January, some regions are already nearing these seasonal peak levels. This increase in RSV activity is also coinciding with increased activity of multiple other respiratory viruses like influenza, rhinoviruses, and enteroviruses, and of course, SARS-CoV-2 continues to circulate.

RSV is overlooked in adult patients, though it is a common cause of pneumonia and respiratory disease in adults. The clinical presentation of RSV in adults is hard to differentiate from that of influenza and from COVID-19, so consider RSV as a possible diagnosis. Patients should be tested for RSV when indicated. Confirming RSV infection, especially in seriously ill patients, can inform prognosis, prevent unnecessary use of antimicrobials, and inform isolation precautions if the patient is in the hospital.

RSV is usually thought of as a disease of young children. Is it more or less dangerous in adults?

RSV is one of the most common causes of childhood respiratory illness, and pediatricians are rightly on alert every season. But RSV isn't just a childhood illness; adults 65 years or older, adults with chronic heart or lung disease, and adults who have weakened immune systems are at high risk for severe illness with RSV. Infection can also trigger worsening of some medical conditions that are common in adults, including asthma, congestive heart failure, and chronic obstructive pulmonary disease (COPD). The clinical presentation of RSV is very similar to that of other respiratory viruses that circulate around the same time, so it's usually not possible to determine which respiratory virus is causing a patient's illness just based on signs and symptoms alone.

What is the timeframe for test results for RSV?

Rapid antigen tests are usually the quickest and can deliver results in less than 30 minutes. However, antigen tests are not as sensitive in detecting RSV in older children and adults because these patients might have lower viral loads in their respiratory specimens compared with infants. Polymerase chain reaction (PCR) assays are probably a provider's best bet when testing older children and adults for RSV. PCR is a highly sensitive test that generates results in a matter of hours, and RSV is typically included in multiplex assays that can test for multiple respiratory pathogens at once. Testing is critical to identify the cause of respiratory illness, particularly in hospitalized or severely ill patients, especially during this time when we have multiple respiratory viruses circulating. While a test result is pending, patients with signs of severe respiratory illness, like tachypnea or hypoxia, should be evaluated in an emergency or inpatient setting as soon as possible.

How is RSV treated?

For patients who can manage their care outside of a hospital setting, they can relieve symptoms with over-the-counter fever reducers and pain medications like acetaminophen or ibuprofen. Patients should also be encouraged to drink fluids because dehydration can be a problem, especially for older adults, when they get viral illnesses. There are clinical trials underway for not only vaccines, but also antivirals that could treat RSV; but currently there is no commercially available treatment specific for the virus.

What is the current progress toward an RSV vaccine?

There are multiple vaccines and other prevention products under development for RSV. Products are targeting many patient populations, including older adults, and use a wide variety of technologies, some of which is building on what was learned during development of the COVID-19 vaccine. Of course, in addition to older adults, there are clinical trials underway to evaluate monoclonal antibodies and vaccines aimed at preventing RSV in infants. One vaccination strategy being studied is vaccinating people who are pregnant to prevent RSV in infants after birth. But I would say there's still a lot unknown about what will be the optimal vaccination strategy, especially if there are vaccines available both for pregnant people and infants.

While we can't predict how soon we may see a vaccine on the market, it is a really good sign that there are multiple products underway by different manufacturers, all of which are being studied at the same time. It's a promising time for RSV prevention.

Do we know why RSV rates are higher so far this season compared with the past?

There's nothing conclusive that can be said. RSV, and other respiratory viruses as well, really declined during the first couple years of the COVID-19 pandemic. Because fewer people may have been exposed to RSV in the past few years, we may not have the typical level of immunity that we would see during a normal winter season before the COVID-19 pandemic. Changes to guidelines in social distancing also mean that more people are exposed to viruses like RSV. But that is a hypothesis; surveillance data can't tell us what is causing what we are seeing.

Health experts have warned of multiple circulating viruses this year with COVID-19, flu, and RSV. How can providers advise patients to prepare?

For the past 2 years, respiratory disease has been dominated by COVID-19. Now there are multiple respiratory viruses co-circulating, and we know that can put additional strain on the healthcare system. But thankfully, many of the same actions that we've been taking to protect ourselves and protect others from COVID-19 can also prevent transmission of other respiratory viruses, including RSV and influenza. To protect against influenza, people should get this season's flu vaccine. Even if people get the flu after being vaccinated, the vaccine can lower the risk for severe illness. People who develop symptoms of a respiratory virus and are tested and diagnosed early for influenza can initiate treatment with the drug oseltamivir (Tamiflu). COVID-19 prevention means staying up-to-date on vaccines, and if you develop symptoms, getting tested so you can know if you are positive and receive appropriate treatment. Consider wearing a mask if you're in an area with medium or high community transmission levels.

For all respiratory viruses, including RSV, influenza, and COVID-19, prevention means washing hands often with soap and water for at least 20 seconds; avoiding touching the mouth, nose, and eyes with unwashed hands; covering coughs and sneezes; cleaning and disinfecting surfaces; and staying home when sick.

Follow the CDC on Twitter

Follow Medscape on Facebook, Twitter, Instagram, and YouTube

Public Information from the CDC and Medscape

Cite this: Michael Melgar. Adult RSV: Q&A With the CDC's Michael Melgar, MD - Medscape - Nov 10, 2022.