RSV Vaccine Coadministration Lowered Antibodies Despite Efficacy

Pharmacists administering the AS01E-adjuvanted RSV Prefusion F protein-based (RSVPreF3 OA) vaccine (Arexvy) alongside other shots may be trading a small drop in antibody response for patient convenience, according to a study showing lower respiratory syncytial virus (RSV) antibody levels with same-day coadministration.¹ Despite the vaccine displaying efficacy when paired with other immunizations and when not, this decrease in antibody levels may create uncertainty regarding vaccine coadministration.

“Vaccine coadministration, in theory, should support vaccine uptake by making vaccination more convenient for the public,” according to authors of a study in Human Vaccines & Immunotherapeutics.² “Improving convenient access to vaccination is one of the World Health Organization’s key recommendations to address falling vaccine uptake. On the other hand, coadministration may be rejected by the public and could reduce trust in vaccination programs overall.”

A systematic review and meta-analysis, containing 6 randomized controlled trials involving 5455 adults aged 50 and older, evaluated same-day RSVPreF3 OA coadministration against sequential vaccination given 1 month apart.

Results show that same-day coadministration produced approximately 9% lower RSV-neutralizing antibody titers compared with sequential dosing. Pooled geometric mean ratios were 0.895 for RSV-A and 0.922 for RSV-B across partner vaccines including pneumococcal, shingles, COVID-19, and influenza.

Despite these numerical reductions, the clinical impact of slightly lower antibody titers remains uncertain because no established antibody threshold exists for clinical protection against RSV disease.

READ MORE: CDC Opens Orders for COVID-19 Vaccines in Vaccines for Children

Understanding Partner Vaccine Responses and Immunogenicity Tradeoffs

Partner vaccine responses varied by formulation and target pathogen. In per-protocol evaluations, non-inferiority was achieved when coadministering RSVPreF3 OA with the 20-valent pneumococcal conjugate vaccine (PCV20) and the recombinant zoster vaccine. A Phase 3 trial also confirmed non-inferiority with seasonal quadrivalent influenza vaccination, showing a 9.5-fold increase in RSV-A antibodies and a 7.7-fold increase in RSV-B antibodies.^1,3

However, non-inferiority was not demonstrated for the SARS-CoV-2 XBB.1.5 booster or the A/H3N2 strain in an adjuvanted influenza vaccine. Serious adverse event rates remained low and equivalent across schedules, confirming that same-day coadministration does not compromise patient safety.¹

Official Guidelines and Patient Attitudes Toward Same-Day Shots

The CDC’s Advisory Committee on Immunization Practices (ACIP) recommends RSV vaccination for adults aged 75 and older, as well as adults aged 50 to 74 at increased risk for severe disease.^4,5

Because RSV eligibility coincides with seasonal influenza, COVID-19, and pneumococcal schedules, official guidelines support coadministration to prevent missed opportunities. Qualitative and survey reviews show that patient attitudes toward coadministration are mixed.^1,2,5

Although convenience and reduced clinic visits motivate many adults, others express concern about potential side effects or receiving multiple injections simultaneously. Direct recommendations from health care providers serve as the most critical motivator for overcoming patient hesitation.²

The Pivotal Role of Community Pharmacists in Immunization Access

Community pharmacists serve as essential leaders in adult immunization and clinical consultation. Retail pharmacies deliver between 6.5 and 8.5 million weekly RSV vaccine doses to older adults, exceeding the administration rate of medical offices. Pharmacists are also well-positioned to educate patients on balancing minor antibody decreases against the convenience and immediate protection of same-day vaccination.⁵

However, navigating evolving reimbursement and policy landscapes presents ongoing challenges for frontline clinicians.⁶

According to Adam Colborn, JD, vice president of government affairs at the Academy of Managed Care Pharmacy (AMCP), recent policy disruptions and delays in ACIP recommendations create potential coverage lag times and administrative confusion for newly updated vaccines or expanded indications. Because pharmacists now deliver more than half of all immunizations, they must manage these operational hurdles while reassuring patients about coverage and care on the date of service.

By discussing safety evidence and individual health risks, pharmacists help older adults achieve timely immunization against severe respiratory illness.^1,5

“Non-inferiority was not demonstrated for the SARS-CoV-2 XBB.1.5 and adjuvanted-QIV A/H3N2 antibody endpoints in the original per-protocol analyses,” concluded the authors.¹ “Coadministration may be considered for the evaluated vaccine combinations within approved product information and applicable immunization guidelines. Further evidence on clinical protection and safety would inform these scheduling decisions, given the low to very low certainty of the RSV antibody evidence.”

READ MORE: Immunization Resource Center

REFERENCES

1. Jiang S, Liu Y, Cui R. Immunogenicity and safety of RSVPreF3 OA coadministration versus sequential administration in adults: a systematic review and meta-analysis. Vaccines. 2026; 14(9):826. https://doi.org/10.3390/vaccines14090826

2. Lazarus R, Williams V, Cochrane H, et al. Attitudes to vaccine co-administration in adults: a scoping review of qualitative evidence. Hum Vaccin Immunother. 2026 Dec;22(1):2616140. doi: 10.1080/21645515.2026.2616140

3. Chandler R, Montenegro N, Llorach C, et al. Immunogenicity, reactogenicity, and safety of AS01E-adjuvanted RSV Prefusion F protein-based candidate vaccine (RSVPreF3 OA) when co-administered with a seasonal quadrivalent influenza vaccine in older adults: results of a Phase 3, open-label, randomized controlled trial. Clin Infect Dis. 2024 Jan 8;83(1):e62–70. doi: 10.1093/cid/ciad786

4. ACIP recommendations: respiratory syncytial virus (RSV) vaccine immunizations. CDC. July 26, 2024. Accessed September 30, 2026. https://www.cdc.gov/acip-recs/hcp/vaccine-specific/rsv.html

5. Ng KE, Bradley N. Pharmacists’ role in respiratory syncytial virus. U.S. Pharmacist. 2026;51(4):23-26. https://www.uspharmacist.com/article/peripheral-arterial-disease-from-a-community-pharmacy-perspective

6. Gallagher A, Colborn A. Worth a Shot: how ACIP changes might impact vaccine access, coverage. Drug Topics. September 17, 2026. Accessed September 30, 2026. https://www.drugtopics.com/view/worth-a-shot-how-acip-changes-might-impact-vaccine-access-coverage