Respiratory syncytial virus (RSV) vaccines: Arexvy, Abrysvo and mResvia

The disease and why it matters

Respiratory syncytial virus (RSV) causes respiratory illness in people of all ages. It is one of the most common causes of childhood illness and the most common cause of hospitalization in infants, and it also causes severe disease and hospitalizations in adults, especially older adults and those with certain risk factors. ^[1]

In most regions of the United States RSV season starts in the fall and peaks in the winter, but timing and severity in a given community vary from year to year. ^[1]

Adults who get RSV usually have mild or no symptoms consistent with an upper respiratory tract infection, and milder illness typically resolves in 1 to 2 weeks; RSV can also cause severe disease and hospitalization in adults and can exacerbate asthma, chronic obstructive pulmonary disease and heart failure. ^[1]

Two to three percent of infants under 6 months of age are hospitalized with RSV every year. ^[1] RSV spreads through direct contact with the virus, for example when droplets from an infected person's cough or sneeze reach the eyes, nose or mouth, and by touching a contaminated surface and then the face. ^[2]

Video and figures

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What is respiratory syncytial virus (RSV)?
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CDC states that there are three FDA-licensed RSV vaccines recommended for adults 50 and older (Arexvy, mResvia and Abrysvo) and no preference for which one adults should receive. Only Abrysvo is recommended for pregnant women; Arexvy and mResvia are not approved for use during pregnancy. ^{[12] [13]}

CDC reports that the RSV vaccines are not currently annual vaccines, so a person who has already received one dose has completed vaccination and should not receive another dose at this time. ^[12]

Who should get it

FDA labeling is broader than CDC's recommendation: all three vaccines are labeled for adults 60 years and older and for adults 18 through 59 years at increased risk of RSV lower respiratory tract disease, while CDC recommends vaccination for all adults 75 and older and for adults 50 through 74 at increased risk. CDC says ACIP and CDC have been reviewing evidence for use in adults 18 through 49 years at increased risk and will continue considering new evidence. ^{[3] [9] [6] [12]}

• CDC lists these conditions as increasing the risk of severe RSV illness: chronic cardiovascular disease, chronic lung or respiratory disease, end-stage renal disease or dependence on dialysis, diabetes mellitus complicated by chronic kidney disease, neuropathy or retinopathy or requiring insulin or an SGLT2 inhibitor, neurologic or neuromuscular conditions impairing airway clearance or respiratory muscle strength, chronic liver disease, chronic hematologic conditions such as sickle cell disease or thalassemia, severe obesity (body mass index of 40 kg/m2 or more), moderate or severe immune compromise, and residence in a nursing home. ^[12]
• CDC also includes other chronic medical conditions or risk factors that a healthcare provider determines would increase the risk of severe disease from a viral respiratory infection, for example frailty, concern for undiagnosed chronic conditions, or living in a remote or rural community where escalation of care is challenging. ^[12]
• Patient attestation is sufficient evidence of a risk factor, and vaccinators should not deny RSV vaccination because of lack of medical documentation. ^[1]

Efficacy and effectiveness (CDC summary): in 2023–2024 real-world studies Arexvy was approximately 77% effective against RSV-associated emergency department encounters and 83% against RSV-associated hospitalizations in adults 60 and older, and Abrysvo approximately 79% and 73%. For mResvia, CDC reports trial efficacy against symptomatic RSV of approximately 80% during the first 4 months, 56% during the first 12 months and 34% through 18 months after vaccination in participants 60 and older. ^[12]

Immunity is not lifelong: CDC notes clinical trial data showed durable protection against symptomatic RSV lower respiratory tract disease through at least 23 months with Arexvy and at least 16 months with Abrysvo, with some waning over time. ^[12]

Dosing and schedule, including catch-up

Each vaccine is given as a single 0.5 mL intramuscular dose: Arexvy and Abrysvo after reconstitution (a vial-and-prefilled-syringe presentation yields approximately 0.5 mL), and mResvia as a single 0.5 mL dose from a prefilled syringe. ^{[3] [6] [9]}

In subsequent pregnancies additional doses are not recommended; infants born to women who received the vaccine during a previous pregnancy should receive nirsevimab. ^[19]

Pregnant women more than 36 weeks 6 days along should not be vaccinated, because it is unlikely there will be enough time for antibodies to develop, cross the placenta and protect the infant; the infant should instead receive nirsevimab before or at the start of the RSV season. ^[13]

Maternal vaccine should not be given outside the September through January window except in areas where RSV circulation is less predictable, including Alaska and tropical climates (such as southern Florida, Guam, Hawaii, Puerto Rico, U.S.-affiliated Pacific Islands and the U.S. Virgin Islands). ^[13]

Administration

• Arexvy (vial and vial): withdraw the adjuvant suspension, transfer it slowly into the lyophilized antigen vial, gently swirl until dissolved (do not shake vigorously), withdraw 0.5 mL and give intramuscularly; use only the supplied adjuvant suspension. After reconstitution, give immediately or store protected from light at 2°C to 8°C or at room temperature up to 25°C and use within 4 hours. ^[3]
• Abrysvo: reconstitute the lyophilized antigen with the sterile water diluent (Act-O-Vial, vial and prefilled syringe, or vial and vial presentation), gently swirl until the powder is dissolved, and do not shake. ^[6]
• mResvia: a frozen prefilled syringe that must be thawed before use (2°C to 8°C for 100 minutes for a single syringe, or 15°C to 25°C for 40 minutes); do not shake, do not refreeze after thawing, and do not administer if the vaccine is discolored or contains other particulate matter; it is a white to off-white suspension that may contain visible white or translucent product-related particulates. ^[9]
• CDC states that RSV vaccines can be coadministered with other adult vaccines at the same visit; the limited data available show that coadministration with other respiratory virus vaccines may result in lower antibody titers, the clinical significance of which is unknown, and coadministration may increase common side effects. ^[12]
• For pregnant women, CDC says maternal RSV vaccine can be given at the same visit as Tdap, COVID-19 and influenza vaccines. ^[13]
• Syncope can occur with injectable vaccines; procedures should be in place to avoid injury from fainting. ^[9]

Storage and handling

The Abrysvo Act-O-Vial stoppers, vial stoppers, and syringe tip cap and rubber plunger, and the mResvia prefilled-syringe tip cap and plunger, are not made with natural rubber latex. ^{[6] [9]}

Contraindications and precautions

• Contraindication: a history of severe allergic reaction (e.g., anaphylaxis) to any component of the vaccine. ^{[3] [6] [9] [20]}
• Warning: the results of postmarketing observational studies suggest an increased risk of Guillain-Barré syndrome during the 42 days following vaccination with Arexvy and with Abrysvo. ^{[3] [6]}
• Abrysvo carries a warning on a numerical imbalance in preterm births in vaccine recipients compared with placebo in two clinical studies; data are insufficient to establish or exclude a causal relationship, and to avoid the potential risk of preterm birth it is given at 32 through 36 weeks gestational age. ^[6]
• Precaution: patients with a minor acute illness such as a cold can be vaccinated, but with moderate or severe acute illness, with or without fever, vaccination should generally be deferred until the patient's health improves. ^[13]
• Immunocompromised individuals, including those receiving immunosuppressive therapy, may have a diminished immune response to the vaccines. ^{[6] [9]}

Safety and adverse events

CDC refers providers to each manufacturer's package insert and the CDC RSV Vaccine Information Statement for contraindications, precautions and additional safety information, and asks that adverse events be reported to VAERS even when it is unclear the vaccine caused them. ^[12]

Guillain-Barré syndrome (GBS): the Arexvy and Abrysvo labels state that postmarketing observational study results suggest an increased risk during the 42 days after vaccination, while CDC's VIS (edition January 31, 2025) says serious neurologic conditions including GBS have been reported after RSV vaccination in some older adults and that an increased risk of GBS among persons aged 60 years and older could not be confirmed or ruled out at that time. ^{[3] [6] [2]}

People sometimes faint after medical procedures, including vaccination; patients should tell the provider if they feel dizzy or have vision changes or ringing in the ears. ^[2]

Special populations

Lactation: for Abrysvo and mResvia it is not known whether the vaccine is excreted in human milk, and the label advises weighing the developmental and health benefits of breastfeeding with the mother's clinical need for the vaccine. ^{[6] [9]}

Younger adults: FDA has approved Abrysvo and mResvia (and, in 2026, Arexvy) for adults 18 through 59 years at increased risk, while CDC's adult guidance page notes that ACIP and CDC continue to review evidence for adults 18 through 49 years at increased risk. ^{[12] [3] [6] [9]}

Infants: CDC recommends either the maternal vaccine or an infant RSV antibody (nirsevimab or clesrovimab) given after birth to protect infants, and nirsevimab for a small group of children 8 through 19 months entering their second RSV season. ^[1]

Counseling pearls for the pharmacy counter

• A recommendation from a healthcare provider is one of the most important factors that influences a patient's choice to accept a new prevention product or vaccine. ^[1]
• Explain that RSV vaccination is currently a single dose, not an annual vaccine, and that the best time to vaccinate is late summer or early fall. ^[12]
• Counsel that a sore arm, tiredness, headache and muscle aches are common after vaccination, and that people sometimes faint after vaccination. ^{[3] [2]}
• Encourage patients to enroll in v-safe and to report adverse events to VAERS (1-800-822-7967). ^[12]

Common patient questions

References

1. Centers for Disease Control and Prevention. Clinical overview of RSV. Page dated August 18, 2025. Accessed October 11, 2026. https://www.cdc.gov/rsv/hcp/clinical-overview/index.html. Accessed October 11, 2026.
2. Centers for Disease Control and Prevention. RSV (respiratory syncytial virus) vaccine: what you need to know. Vaccine Information Statement, January 31, 2025. Accessed October 11, 2026. https://www.cdc.gov/vaccines/hcp/current-vis/rsv.html. Accessed October 11, 2026.
3. AREXVY (respiratory syncytial virus vaccine, adjuvanted) for injectable suspension, for intramuscular use: prescribing information. GlaxoSmithKline Biologicals; revised 7/2026. U.S. Food and Drug Administration. Accessed October 11, 2026. https://www.fda.gov/media/167805/download?attachment. Accessed October 11, 2026.
4. U.S. Food and Drug Administration. AREXVY (STN 125775), product page (content current as of 07/28/2026). Accessed October 11, 2026. https://www.fda.gov/vaccines-blood-biologics/arexvy. Accessed October 11, 2026.
5. U.S. Food and Drug Administration. Replacement BLA approval letter, Respiratory Syncytial Virus Vaccine, Adjuvanted (AREXVY), STN BL 125775/0 (effective approval date May 3, 2023). Accessed October 11, 2026. https://www.fda.gov/media/167806/download?attachment. Accessed October 11, 2026.
6. ABRYSVO (respiratory syncytial virus vaccine) for injection, for intramuscular use: prescribing information. Pfizer Inc.; revised 12/2025. U.S. Food and Drug Administration. Accessed October 11, 2026. https://www.fda.gov/media/168889/download?attachment. Accessed October 11, 2026.
7. U.S. Food and Drug Administration. ABRYSVO (STN 125769; 125768), product page (content current as of 12/19/2025). Accessed October 11, 2026. https://www.fda.gov/vaccines-blood-biologics/abrysvo. Accessed October 11, 2026.
8. U.S. Food and Drug Administration. BLA approval letter, Respiratory Syncytial Virus Vaccine (ABRYSVO), STN BL 125769/0. May 31, 2023. Accessed October 11, 2026. https://www.fda.gov/media/168890/download?attachment. Accessed October 11, 2026.
9. MRESVIA (respiratory syncytial virus vaccine) injectable suspension, for intramuscular use: prescribing information. ModernaTX, Inc.; revised 8/2026. U.S. Food and Drug Administration. Accessed October 11, 2026. https://www.fda.gov/media/179005/download?attachment. Accessed October 11, 2026.
10. U.S. Food and Drug Administration. MRESVIA (STN 125796), product page (content current as of 08/10/2026). Accessed October 11, 2026. https://www.fda.gov/vaccines-blood-biologics/vaccines/mresvia. Accessed October 11, 2026.
11. U.S. Food and Drug Administration. Replacement BLA approval letter, Respiratory Syncytial Virus Vaccine (MRESVIA), STN BL 125796/0 (effective approval date May 31, 2024). Accessed October 11, 2026. https://www.fda.gov/media/179015/download?attachment. Accessed October 11, 2026.
12. Centers for Disease Control and Prevention. RSV vaccine guidance for adults. Page dated February 24, 2026. Accessed October 11, 2026. https://www.cdc.gov/rsv/hcp/vaccine-clinical-guidance/adults.html. Accessed October 11, 2026.
13. Centers for Disease Control and Prevention. RSV vaccine guidance for pregnant women. Page dated August 30, 2024. Accessed October 11, 2026. https://www.cdc.gov/rsv/hcp/vaccine-clinical-guidance/pregnant-people.html. Accessed October 11, 2026.
14. American Academy of Family Physicians. Adults 19 and older immunization schedules (adopted version; page shows no version date). Accessed October 11, 2026. https://www.aafp.org/clinical-insights/immunizations-and-vaccines/immunizations-schedules-resources/adult-immunization-schedules. Accessed October 11, 2026.
15. Congressional Research Service. The 2026 Childhood Immunization Schedule (R48982). June 11, 2026. Accessed October 11, 2026. https://www.congress.gov/crs_external_products/R/PDF/R48982/R48982.1.pdf. Accessed October 11, 2026.
16. Centers for Disease Control and Prevention. CDC acts on Presidential Memorandum to update childhood immunization schedule. News release, January 5, 2026. Accessed October 11, 2026. https://www.cdc.gov/media/releases/2026/2026-cdc-acts-on-presidential-memorandum-to-update-childhood-immunization-schedule.html. Accessed October 11, 2026.
17. Centers for Disease Control and Prevention. Healthcare professionals: immunization schedules. Accessed October 11, 2026. https://www.cdc.gov/vaccines/hcp/imz-schedules/index.html. Accessed October 11, 2026.
18. American Academy of Pediatrics. AAP releases recommended childhood and adolescent immunization schedule for 2026. HealthyChildren.org news. Accessed October 11, 2026. https://healthychildren.org/English/news/Pages/AAPs-recommended-childhood-and-adolescent-immunization-schedule-for-2026.aspx. Accessed October 11, 2026.
19. Centers for Disease Control and Prevention. Adult immunization schedule notes: recommendations for ages 19 years or older, United States, 2025. July 2, 2025. Accessed October 11, 2026. https://www.cdc.gov/vaccines/hcp/imz-schedules/adult-notes.html. Accessed October 11, 2026.
20. Centers for Disease Control and Prevention. Adult immunization schedule appendix: guide to contraindications and precautions, United States, 2025. July 2, 2025. Accessed October 11, 2026. https://www.cdc.gov/vaccines/hcp/imz-schedules/adult-appendix.html. Accessed October 11, 2026.