top of page
  • Writer's pictureFibonacciMD

The RSV (Respiratory Syncytial Virus) Vaccine for Elderly Adults. Is It Worth Getting?

RSV (respiratory syncytial virus) has long been known as a children’s disease and is thought to be the leading cause of infant pneumonia in the world. RSV can also be a serious disease in elderly adults due to waning immunity.

Infectious Disease


Respiratory Syncytial Virus RSV vaccine

RSV (respiratory syncytial virus) has long been known as a children’s disease, causing runny nose, coughing, sneezing, fever, and/or wheezing and is thought to be the leading cause of infant pneumonia in the world.[1] Most patients recover in a week or two. RSV can also be a serious disease in elderly adults due to waning immunity, and can cause dyspnea (shortness of breath), hypoxia (low blood oxygen) and pneumonia.[2]

RSV in Adults

In one study, RSV illness developed annually in approximately 3% to 7% of healthy older adults and 4% to 10% of high-risk adult subjects.[3] It is estimated that yearly in the United States between 60,000-160,000 older adults are hospitalized and 6,000-10,000 die due to RSV infection.[4] In one study of older adults who were hospitalized with RSV disease, 18% were admitted to an intensive care unit and 5.6% died.[5]

Adults at highest risk for severe RSV infection include:

  • Older adults

  • Adults with chronic heart or lung disease such as asthma, chronic obstructive pulmonary disease or congestive heart failure

  • Adults with weakened immune systems

  • Adults living in nursing homes or long-term care facilities[4]

CDC Vaccination Recommendations

On June 29th, 2023 the CDC Advisory Committee on Immunization Practices’ (ACIP) published recommendations for use of new Respiratory Syncytial Virus (RSV) vaccines for people ages 60 years and older, using shared clinical decision-making. This means these individuals may receive a single dose of the vaccine based on discussions with their healthcare provider about whether RSV vaccination is right for them.[6]

How the Vaccine Works

An RSV protein called RSV prefusion F protein (RSVpreF) provides potent stimulation to the immune system. The RSV vaccines, (which are not mRNA vaccines) work by introducing two RSV subtypes of inactivated RSVpreF into the body. If the person becomes infected, the vaccine stimulated immune system allows rapid recognition of the RSV virus which can help prevent acute or severe disease.[7,8] Abrysvo, manufactured by Pfizer and Arexvy, manufactured by GSK, both are FDA approved as RSV vaccines in adults. (Vaccinating pregnant women to give passive RSV antibodies to neonates is being investigated, and an mRNA vaccine is in phase three testing).[7,9,10]

Vaccine Studies

In a manufacture sponsored study, the Pfizer vaccine Abrysvo had an efficacy of 66.7% in preventing pneumonia, and a 62.1% efficacy for preventing RSV acute respiratory illness compared to placebo. (In actual numbers, out of a total of 34,284 participants there were 11 participants in the vaccine group and 33 participants in the placebo group who got pneumonia and 22 participants in the vaccine group who developed an acute RSV respiratory illness compared to 58 participants in the placebo group) There were 2 cases of Guillain-Barré variants* in the vaccine group of 17,215 subjects, which works out to 1.16 cases per 10,000 doses.[11]

* (A condition where a person's immune system attacks peripheral nerves.)

In Arexvy manufacture sponsored trials, vaccine efficacy compared to a placebo group against confirmed RSV-related lower respiratory tract disease (pneumonia) was 82.6%, and was 71.7% against RSV-related acute respiratory infection.[8]

Most adverse reactions to Arexvy were typical for vaccines and included local pain, fatigue, myalgias, headache, arthralgias and fever. In the phase three 24,966 subject trial, atrial fibrillation developing within 30 days was reported in 10 participants who received Arexvy and 4 participants who received placebo (of which 7 events in Arexvy arm and 1 event in placebo arm were serious). However, at 6 months atrial fibrillation was reported in 13 participants who received Arexvy and 15 participants in the placebo group. The manufacturer states that currently available information is insufficient to determine a causal relationship of atrial fibrillation to the vaccine. Although no Guillain-Barré syndrome cases were reported in the phase three trial, in one other trial a case of Guillain-Barré syndrome was reported nine days after an Arexvy vaccination. In another trial there were two reported cases of acute disseminated encephalomyelitis** 7 and 22 days after an Arexvy vaccination in subjects who had also concomitantly received the Fluarix Quadrivalent influenza vaccine.[12]

** (A neurological disorder characterized by widespread inflammation of the brain and spinal cord.)

Need for Revaccination

Data presented to the FDA indicated that Arexvy vaccination could be protective for at least two years, but there is no recommendation as of yet if the vaccination needs to be repeated or how frequently it may need be repeated.[7,13]


The FDA has approved bivalent RSV vaccines for those over 60 years of age using shared clinical decision making to decide if it is appropriate for that person. There is a considerable amount of serious disease in the elderly from RSV and there is some data indicating that vaccination can reduce the chance of contracting RSV pneumonia 67% to 83% compared to placebo.

The chance of a placebo group subject in the Abrysvo study getting an acute RSV infection was 0.19% (33/17,069) and was 0.76% (95/12,494) in the Arexvy placebo group.[8,10] This was much lower than one earlier study which found that 3% to 7% of healthy older adults and 4% to 10% of high-risk elderly subjects got infected with RSV each year.[3] It is possible that the lower numbers of RSV infections found in studies done during the COVID-19 era were due to precautions taken by some subjects during that time.

There is a small chance of a serious adverse event from vaccination.

The amount of time until revaccination has not been determined, although there is some evidence of continued protection at two years.

Considering the potential seriousness of an RSV infection in the elderly, there are patients that might benefit from vaccination, especially those with underlying high-risk medical conditions. The FDA has indicated this should be a decision made by physicians in conjunction with their patients to decide if the benefits versus risks of vaccination against RSV infection warrant vaccination for that patient.



[1] Karron , RA. RSV Illness in the Young and the Old — The Beginning of the End? N Engl J Med 388:1522-1524. April 20, 2023. Retrieved from:

[3] Falsey AR, Hennessey PA, Formica MA, Cox C, Walsh EE. Respiratory syncytial virus infection in elderly and high-risk adults. N Engl J Med 2005;352:1749-1759. Retrieved from:

[4] RSV in Older Adults and Adults with Chronic Medical Conditions. CDC. Last Reviewed: July 14, 2023. Retrieved from:

[5] Bradley Ackerson and others, Severe Morbidity and Mortality Associated With Respiratory Syncytial Virus Versus Influenza Infection in Hospitalized Older Adults, Clinical Infectious Diseases, Volume 69, Issue 2, 15 July 2019, Pages 197–203. Retrieved from:

[6] CDC Recommends RSV Vaccine For Older Adults. CDC. June 29, 2023. Retrieved from:

[7] Katella K. Should You Get the New RSV Vaccine? Yale Medicine. originally published: July 24, 2023. Updated: August 28, 2023. Retrieved from:

[8]Papi a et al. Respiratory Syncytial Virus Prefusion F Protein Vaccine in Older Adults. N Engl J Med 2023; 388:595-608. February 16, 2023. Retrieved from:

[9]Kampmann B. et al. Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants. N Engl J Med 2023; 388:1451-1464. April 20, 2023. Retrieved from:

[10] Moderna Announces mRNA-1345, an Investigational Respiratory Syncytial Virus (RSV) Vaccine, Has Met Primary Efficacy Endpoints in Phase 3 Trial in Older Adults. Moderna News Details. January 17, 2023. Retrieved from:

[11] Walsh EE et al. Efficacy and Safety of a Bivalent RSV Prefusion F Vaccine in Older Adults. N Engl J Med 2023; 388:1465-1477. April 20, 2023. Retrieved from:

[12] AREXVY prescribing information. GlaxoSmithKline. Revised: 5/2023. Retrieved from:

[13] GSK shares positive data for Arexvy, its respiratory syncytial virus (RSV) older adult vaccine, indicating protection over two RSV seasons. GSK. 21 June 2023. Retrieved from:


bottom of page