Addressing RSV in Older Adults

Key Takeaways

• Respiratory syncytial virus can be the cause of severe disease and mortality in adults older than 65 years of age.
• Respiratory syncytial virus is underdiagnosed in this population.
• Several new vaccines are in development for respiratory syncytial virus.

Burden of RSV Infection in Older Adults
Globally, approximately 64 million people are affected with respiratory syncytial virus (RSV) each year, causing approximately 160,000 deaths. In the United States, there are approximately 177,000 cases of older adults who are hospitalized with RSV every year. Among these cases, 14,000 older adults die from RSV each year.

Similar to symptoms of the cold and flu viruses, the symptoms of RSV may include a fever, runny nose, coughing, and sneezing. Thus, RSV is commonly undiagnosed in primary care, including in older adults. Other RSV symptoms include wheezing and a reduced appetite.

The transmission of RSV occurs through aerosolized viral droplets, skin-to-skin contact, or touching contaminated surfaces. Although RSV can manifest primarily as a coldlike syndrome, it can develop into a more severe lower-respiratory infection that may result in hospitalization and death.

Deficiencies in Screening and Awareness
RSV can be unrecognized or underrecognized in my clinical practice and across the United States for several reasons. First, RSV is indistinguishable from other upper-respiratory infections and might be mistaken for another viral respiratory infection. Second, adults tend to have a lower viral load in their respiratory specimens. Therefore, even if a healthcare professional tests for RSV, the test may be negative, particularly with rapid antigen-type tests (as opposed to a polymerase chain reaction [PCR] test). Third, when people are admitted to the hospital, the recorded diagnosis often is chronic obstructive pulmonary disease or a congestive heart failure exacerbation, when in fact RSV might have been the precipitant for those events. Lastly, there is no real motivation to check for RSV because therapeutic options that are specific to RSV are not currently available.

However, awareness of RSV may change in the COVID-19 era. Whereas RSV was previously tested primarily in inpatient settings, I believe that outpatient PCR testing is becoming more common. In my clinical practice, outpatient PCR testing is now used to detect COVID-19, influenza, and RSV, and this increase in outpatient PCR testing might increase our awareness of the prevalence of RSV. Having said that, given the cost of PCR testing, it is unknown whether continued outpatient testing will be sustainable after the pandemic.

Emerging Vaccine Formulations for Older Adults
Several vaccine candidates for older adults are in the pipeline, including RSV subunit vaccines, an RSV vector vaccine (Ad26.RSV.preF), an mRNA vaccine (mRNA-1345), and a live recombinant vaccine (MVA-BN-RSV).

Two candidate vaccines incorporating a bivalent prefusion F subunit are the RSVpreF vaccine and the RSVpreF3 vaccine, the latter of which also includes an adjuvant, AS01, to boost the immune response for an older population. Separate phase III trials of the RSVpreF and RSVPreF3 vaccines are ongoing or planned. The adenovirus serotype 26 (Ad26).RSV.preF-based vaccine, combined with a prefusion F protein, uses a vector to transport genetic material to start viral protein formulation, causing an antibody response. This vaccine candidate will be assessed further in older adults in a phase III trial.

Another vaccine candidate in a phase II/III trial in older adults consists of mRNA-1345. It is a single-dose mRNA vaccine that encodes for the RSV preF glycoprotein. MVA-BN-RSV is another vaccine candidate in a phase III trial in older adults. This recombinant vaccine includes RSV antigens (RSV surface proteins F and G for both A and B subtypes and internal antigens N and M2).

Outlook
Based on morbidity and mortality statistics in older adults, it is clear that RSV should be considered more carefully in the differential diagnosis of upper- and lower-respiratory infections in older adults. Because there is no antiviral medication specific for RSV, the treatment primarily has been supportive care.

The advent of RSV vaccines may change the landscape of RSV in older adults. However, the current annual vaccine schedule for older adults is becoming challenging. Currently, the CDC recommends an annual influenza vaccine, as well as frequent COVID-19 vaccinations to prevent respiratory infections, among several other routinely recommended vaccines. Will it be possible to add the RSV vaccine to this schedule in an efficient way for older adults?

There is some consideration for combining the mRNA RSV, influenza, and COVID-19 booster vaccines into a single dose. This could be an excellent way to try to consolidate the vaccination effort in older adults. Although I strongly believe that my older patients will be interested in receiving the RSV vaccine, they will appreciate the reduced burden of frequent office visits to receive multiple vaccinations.

Learn More at Family Medicine Experience 2022
Join me and a panel of experts as we discuss RSV at our upcoming live or virtual symposium. We’ll discuss diagnostic challenges, recent RSV vaccine safety and efficacy data, and overcoming barriers to the implementation of vaccines for older adults in primary care settings.

Your Thoughts?
Would you recommend an RSV vaccine for your older adult patients if approved? Join the discussion by posting a comment.