Respiratory Syncytial virus (RSV) season has started in Florida, indicating the rest of the country will see infections in the coming weeks. Luckily, we have more tools to prevent RSV infections than ever before. In the August 2024 issue of Vaccine Update, we reviewed key lessons learned for using these tools to protect infants. This month, we will review lessons learned about RSV vaccines for older adults. Last fall, two recombinant RSV vaccines were available. In early 2024, a third vaccine, based on mRNA technology, was added to the options.
As a review, new tools continue to be studied after licensure. These additional studies enable us to learn about real-world effectiveness and rare safety concerns that might not have been detected in clinical trials. At times, the Food and Drug Administration (FDA) will also request specific data after a vaccine is licensed if clinical trials raised a particular question or issue. For example, in the case of the protein-based RSV vaccines for adults, some evidence of Guillain-Barré syndrome (GBS) after vaccination during clinical trials led to a request for additional studies related to this matter. With additional data in hand, vaccine providers can now answer questions commonly asked by their patients about this and other topics.
Which vaccines are available for adults?
Three vaccines are available for adults aged 60 and older this fall. Two are protein-based, Abrysvo and Arexvy. The third, mResvia, is an mRNA-based vaccine, similar to COVID-19 mRNA vaccines. mResvia contains mRNA that codes for the fusion protein (called F protein) in a prefusion confirmation. Because the protein that is produced is in this confirmation, it is referred to as pre-F protein. Arexvy is the only one of the three options that contains an adjuvant, specifically monophoshphoryl lipid A and QS21 — the same adjuvant used in the shingles vaccine.
All three vaccines are recommended for a single lifetime dose and can be administered at the same time as other vaccines.
Each vaccine has unique storage and administration requirements that should be reviewed based on which product your practice provides.
How effectively do the adult RSV vaccines reduce hospitalizations for RSV in the real world?
Clinical trials that occur before a vaccine is licensed determine how well the vaccine is working under optimal conditions; the outcomes are reported as vaccine efficacy. After licensure, it is important to understand how the vaccine works in the population at large when a more diverse group of people receive the vaccine. The real-world utility of the vaccine revealed in these studies is known as vaccine effectiveness.
The clinical trials of the protein-based vaccines demonstrated a 67%-86% reduction of RSV-associated lower respiratory tract disease. Importantly, however, the subjects in these trials included few adults 80 years of age and older, and only about half of the participants reported a previous diagnosis of a chronic condition.
After a season of experience, real world data, which included more elderly and chronically ill people, demonstrated similar vaccine effectiveness. Data presented at the June Advisory Committee on Immunization Practices (ACIP) meeting provided insights based on emergency department visits, hospitalization and critical illness. Highlights included:
- A 75%-80% effectiveness against RSV-associated hospitalization among adults 60 years and older (Investing Respiratory Viruses in the Acutely Ill (IVY) network and Virtual SARS-CoV-2, Influenza, and Other respiratory viruses Network (VISION))
- A 77% effectiveness against any RSV infection based on visits to the emergency room, visits to urgent care and hospitalization (Veterans Health Administration (VHA))
- A 73%-83% effectiveness against hospitalization among immune-compromised individuals 60 years and older (VISION) or 65 years and older (Medicare claims data), respectively
- A 75% effectiveness against hospitalization among patients 65 years and older with end-stage renal disease (Medicare claims data)
Do the protein-based vaccines (Abrysvo and Arexvy) lead to GBS?
The FDA reviewed data from Medicare beneficiaries 65 years and older who received RSV vaccine in fall of 2023. Rates of GBS in the period after vaccination were compared to rates of GBS during a later period in the same person’s life. Early analysis did not support an elevated risk of GBS; however, medical record reviews are ongoing.
What are the recommendations for 2024-2025?
The following adults are currently recommended to get RSV vaccine:
- All adults 75 years and older
- Adults 60 to 74 years of age with chronic conditions that put them at increased risk for severe RSV disease. For details regarding which groups are considered to be at increased risk, check the CDC’s “Clinical Overview of RSV” webpage.
Importantly, adults who got an RSV vaccine last fall do NOT need another dose this year.
Why were the recommendations for adult RSV vaccination changed?
When the protein-based RSV vaccines were approved in 2023, the recommendation was for all individuals 60 and older to receive a single dose based on shared clinical decision making with their provider. With additional data and the benefit of experience related to implementation, the recommendations were updated for 2024. Specifically, clinical trials confirmed the vaccine effectiveness and safety in older adults. Additionally, shared clinical decision making, while useful when there was some uncertainty about the risks and benefits of vaccination for individuals, was cumbersome for providers to implement, particularly due to the additional time required for nuanced conversations during visits. Further, individuals without a provider were at a disadvantage in terms of getting information useful for assessing their risk-benefit calculation. The updated guidance provides more specific recommendations, making vaccine decision making and discussions more straightforward. The September Parents PACK addressed these changes for the public in the “News and Notes” section.
Is there a preferred RSV vaccine between the protein-based vaccines (Abrysvo and Arexvy) and the mRNA vaccine (mResvia)?
No. At this point, we have less data on the mRNA vaccine because it was not available last year. However, the clinical trial data suggested that it will be as effective as the protein-based vaccines; therefore, the CDC did not make a preferential recommendation for any of the RSV vaccines.
Resources
- Respiratory Syncytial Virus (RSV) Vaccine and Monoclonal Antibody
- Advisory Committee on Immunization Practices Slides: Evaluation of Guillain-Barre Syndrome (GBS) Following RSV Vaccination among Adults 65 Years and Older
- Advisory Committee on Immunization Practices Slides: Effectiveness of Adult Respiratory Syncytial Virus (RSV) Vaccines, 2023–2024
- Advisory Committee on Immunization Practices Slides: Risk-Benefit Analysis of RSV Vaccination in Older Adults
Contributed by: Lori Handy, MD, MSCE , Charlotte A. Moser, MS, Paul A. Offit, MD
Respiratory Syncytial virus (RSV) season has started in Florida, indicating the rest of the country will see infections in the coming weeks. Luckily, we have more tools to prevent RSV infections than ever before. In the August 2024 issue of Vaccine Update, we reviewed key lessons learned for using these tools to protect infants. This month, we will review lessons learned about RSV vaccines for older adults. Last fall, two recombinant RSV vaccines were available. In early 2024, a third vaccine, based on mRNA technology, was added to the options.
As a review, new tools continue to be studied after licensure. These additional studies enable us to learn about real-world effectiveness and rare safety concerns that might not have been detected in clinical trials. At times, the Food and Drug Administration (FDA) will also request specific data after a vaccine is licensed if clinical trials raised a particular question or issue. For example, in the case of the protein-based RSV vaccines for adults, some evidence of Guillain-Barré syndrome (GBS) after vaccination during clinical trials led to a request for additional studies related to this matter. With additional data in hand, vaccine providers can now answer questions commonly asked by their patients about this and other topics.
Which vaccines are available for adults?
Three vaccines are available for adults aged 60 and older this fall. Two are protein-based, Abrysvo and Arexvy. The third, mResvia, is an mRNA-based vaccine, similar to COVID-19 mRNA vaccines. mResvia contains mRNA that codes for the fusion protein (called F protein) in a prefusion confirmation. Because the protein that is produced is in this confirmation, it is referred to as pre-F protein. Arexvy is the only one of the three options that contains an adjuvant, specifically monophoshphoryl lipid A and QS21 — the same adjuvant used in the shingles vaccine.
All three vaccines are recommended for a single lifetime dose and can be administered at the same time as other vaccines.
Each vaccine has unique storage and administration requirements that should be reviewed based on which product your practice provides.
How effectively do the adult RSV vaccines reduce hospitalizations for RSV in the real world?
Clinical trials that occur before a vaccine is licensed determine how well the vaccine is working under optimal conditions; the outcomes are reported as vaccine efficacy. After licensure, it is important to understand how the vaccine works in the population at large when a more diverse group of people receive the vaccine. The real-world utility of the vaccine revealed in these studies is known as vaccine effectiveness.
The clinical trials of the protein-based vaccines demonstrated a 67%-86% reduction of RSV-associated lower respiratory tract disease. Importantly, however, the subjects in these trials included few adults 80 years of age and older, and only about half of the participants reported a previous diagnosis of a chronic condition.
After a season of experience, real world data, which included more elderly and chronically ill people, demonstrated similar vaccine effectiveness. Data presented at the June Advisory Committee on Immunization Practices (ACIP) meeting provided insights based on emergency department visits, hospitalization and critical illness. Highlights included:
- A 75%-80% effectiveness against RSV-associated hospitalization among adults 60 years and older (Investing Respiratory Viruses in the Acutely Ill (IVY) network and Virtual SARS-CoV-2, Influenza, and Other respiratory viruses Network (VISION))
- A 77% effectiveness against any RSV infection based on visits to the emergency room, visits to urgent care and hospitalization (Veterans Health Administration (VHA))
- A 73%-83% effectiveness against hospitalization among immune-compromised individuals 60 years and older (VISION) or 65 years and older (Medicare claims data), respectively
- A 75% effectiveness against hospitalization among patients 65 years and older with end-stage renal disease (Medicare claims data)
Do the protein-based vaccines (Abrysvo and Arexvy) lead to GBS?
The FDA reviewed data from Medicare beneficiaries 65 years and older who received RSV vaccine in fall of 2023. Rates of GBS in the period after vaccination were compared to rates of GBS during a later period in the same person’s life. Early analysis did not support an elevated risk of GBS; however, medical record reviews are ongoing.
What are the recommendations for 2024-2025?
The following adults are currently recommended to get RSV vaccine:
- All adults 75 years and older
- Adults 60 to 74 years of age with chronic conditions that put them at increased risk for severe RSV disease. For details regarding which groups are considered to be at increased risk, check the CDC’s “Clinical Overview of RSV” webpage.
Importantly, adults who got an RSV vaccine last fall do NOT need another dose this year.
Why were the recommendations for adult RSV vaccination changed?
When the protein-based RSV vaccines were approved in 2023, the recommendation was for all individuals 60 and older to receive a single dose based on shared clinical decision making with their provider. With additional data and the benefit of experience related to implementation, the recommendations were updated for 2024. Specifically, clinical trials confirmed the vaccine effectiveness and safety in older adults. Additionally, shared clinical decision making, while useful when there was some uncertainty about the risks and benefits of vaccination for individuals, was cumbersome for providers to implement, particularly due to the additional time required for nuanced conversations during visits. Further, individuals without a provider were at a disadvantage in terms of getting information useful for assessing their risk-benefit calculation. The updated guidance provides more specific recommendations, making vaccine decision making and discussions more straightforward. The September Parents PACK addressed these changes for the public in the “News and Notes” section.
Is there a preferred RSV vaccine between the protein-based vaccines (Abrysvo and Arexvy) and the mRNA vaccine (mResvia)?
No. At this point, we have less data on the mRNA vaccine because it was not available last year. However, the clinical trial data suggested that it will be as effective as the protein-based vaccines; therefore, the CDC did not make a preferential recommendation for any of the RSV vaccines.
Resources
- Respiratory Syncytial Virus (RSV) Vaccine and Monoclonal Antibody
- Advisory Committee on Immunization Practices Slides: Evaluation of Guillain-Barre Syndrome (GBS) Following RSV Vaccination among Adults 65 Years and Older
- Advisory Committee on Immunization Practices Slides: Effectiveness of Adult Respiratory Syncytial Virus (RSV) Vaccines, 2023–2024
- Advisory Committee on Immunization Practices Slides: Risk-Benefit Analysis of RSV Vaccination in Older Adults
Contributed by: Lori Handy, MD, MSCE , Charlotte A. Moser, MS, Paul A. Offit, MD