Can mRNA Vaccines Offer Long-Lasting Immunity to Respiratory Viruses?

Background: Why Durable Respiratory Immunity Is Difficult to Achieve

Respiratory viruses — including Respiratory Syncytial Virus (RSV), influenza, SARS-CoV-2, and Monkeypox virus (MPXV) — continue to impose significant global health burdens. A central challenge in respiratory vaccinology is not simply generating an immune response, but sustaining it long enough to provide meaningful real-world protection.

The respiratory tract is an immunologically complex environment. Pathogens typically enter through mucosal surfaces, where systemically generated immunity from intramuscular injections may be slower to act. Truly effective respiratory vaccines likely need to elicit both systemic antibody responses and durable local mucosal immunity — a dual requirement that traditional platforms have struggled to fulfil simultaneously [3].

The global success of mRNA COVID-19 vaccines demonstrated that this platform can rapidly induce strong immune responses. However, questions about the duration of mRNA vaccine-induced immunity — and how to extend it — remain at the frontier of vaccine science. This article synthesises the latest published evidence on whether mRNA technology can be engineered to deliver not just rapid, but truly long-lasting protection against respiratory viruses.

The New Evidence: What Recent Studies Tell Us

Four lines of recent scientific inquiry illuminate the current state of mRNA-based immunity for respiratory and mucosal pathogens: self-amplifying mRNA constructs, nanotechnology-enhanced delivery systems, inhalable vaccine formulations, and comparative immunological benchmarks from live-attenuated vaccine research.

Self-Amplifying mRNA: A Dose-Sparing Approach to Multivalent Immunity

One of the most compelling recent advances is the development of self-amplifying mRNA (SAM) platforms. Unlike conventional mRNA vaccines, which encode only the antigen of interest, SAM constructs incorporate a viral replicase sequence that allows the mRNA to replicate within the host cell, producing higher levels of antigen from a smaller initial dose [1].

A 2025 study published in Vaccine by Chen et al. evaluated SAM vaccine designs against Neisseria meningitidis group B (MenB), a bacterium with a complex antigenic landscape. While MenB is not a respiratory virus, the immunological principles demonstrated have broader applicability to respiratory vaccine design. The researchers constructed and compared several multivalent SAM configurations encoding four distinct antigens: factor H binding protein (fHbp), Neisseria Heparin-Binding Antigen (NHBA), Neisserial adhesin A (NadA), and Porin A (PorA) [1].

The study found that a mixed-delivery approach — where individually encapsulated mRNA–lipid nanoparticles (LNPs) were combined prior to administration (the “PreMix” strategy) — outperformed a tandem fusion construct in which all four antigens were encoded in a single mRNA. The PreMix formulation elicited a serum bactericidal assay (SBA) titer of 1:256 at a 5 µg dose, compared to a titer of only 1:32 with the tandem construct [1].

For respiratory vaccine design, this research highlights a crucial principle: how antigens are combined in mRNA vaccines matters profoundly. For applications requiring multivalent coverage — such as multiple influenza strains or RSV subtypes A and B — the SAM platform’s capacity for flexible antigen combinations while maintaining strong immunogenicity is directly relevant [1]. The authors specifically describe the SAM platform as offering “long-lasting expression,” addressing one of the central questions about mRNA vaccine durability [1].

Nanotechnology-Driven mRNA Vaccines for RSV and Respiratory Pathogens

A 2025 review published in Colloids and Surfaces B: Biointerfaces by Niculescu et al. surveyed nanotechnology-driven vaccines for two pathogens of respiratory relevance: RSV and MPXV [2].

RSV is the leading cause of acute lower respiratory tract infections in young children globally and a major cause of morbidity in elderly adults [4]. The review documents several nanotechnology platforms under development for RSV, including mRNA–lipid nanoparticles, nanocages, virus-like particles, elastin-like polypeptides, and self-aggregating lipopeptides [2]. Each platform aims to enable precise antigen presentation that stimulates both mucosal and systemic immunity.

The review authors note that nanoparticle-based vaccines can mimic viral structures, facilitating targeted interactions with antigen-presenting cells (APCs), optimising antigen presentation, and promoting strong cellular and humoral immune responses [2]. For respiratory viruses, the capacity to engage APCs in mucosal tissues — including dendritic cells lining the airways — is important for generating long-lived tissue-resident memory.

The Niculescu et al. review emphasises that despite promising preclinical findings, no approved MPXV or RSV nanovaccines are currently available as of their 2025 publication [2]. Critical barriers to clinical translation include the need for further characterisation of nanoparticle safety and immunogenicity, scalable manufacturing, and identification of optimal viral antigens for targeting [2].

Inhalable mRNA Vaccines: Targeting Immunity at the Source

Delivering mRNA vaccines directly to the respiratory tract via inhalation has the potential to generate not only systemic antibodies but also local mucosal immunity — including secretory IgA and tissue-resident memory T cells — at the exact site where respiratory pathogens first establish infection.

A 2022 roadmap article in Current Opinion in Biotechnology by Roh, Fromen, and Sullivan outlined both the promise and the challenges of this approach [3]. The authors note that mRNA vaccines offer “exceptional efficacy and versatile capacity to be adapted to new viruses and variants,” but identify “critical questions regarding immune persistence and formulation stability” as major unresolved issues [3]. They frame inhalable mRNA vaccines as a “significant opportunity” to drive “long-lasting, tissue-specific memory responses needed for rapid recall and immediate local protection” [3], while identifying three major translational challenges:

Benchmarking Against Live-Attenuated Vaccines: The RSV Immunological Standard

To contextualise the durability potential of mRNA-induced immunity, it is useful to consider what conventional vaccine platforms have achieved. A 2021 study in the Journal of Virology by Jenkins et al. evaluated a live-attenuated RSV (LAV) vaccine candidate — rgRSV-L(G1857A)-G(L208A) — containing two targeted mutations: one in the S-adenosylmethionine (SAM) binding site of the viral mRNA cap methyltransferase within the large (L) polymerase protein, and another in the G attachment protein that inhibits its cleavage during production in Vero cells [4].

This LAV candidate efficiently induced neutralising antibodies that were long lasting in cotton rats, provided complete protection from RSV challenge, and protected a rhesus macaque from RSV challenge without causing enhanced disease [4]. It demonstrated the ability to stimulate both B and T cell responses by presenting the full viral protein repertoire to the immune system — a property intrinsic to live-attenuated approaches [4].

The Jenkins et al. findings establish that durable, long-lasting neutralising antibody responses against RSV following low-dose immunisation are immunologically achievable. The outstanding question for mRNA platforms is whether they can replicate this durability — particularly given that the SAM platform claims “long-lasting expression” as a mechanistic feature [1] and that inhalable mRNA delivery routes are being designed to generate tissue-resident memory comparable to live-attenuated approaches [3].

Clinical Implications: What This Means for Patients and Clinicians

Taken together, the current body of evidence supports a cautiously optimistic picture for mRNA-based long-lasting respiratory immunity, with important caveats for clinical practice.

Practical Takeaway: A Decision Framework

For healthcare professionals advising patients on respiratory vaccine options, the following framework reflects the current evidence base:

Evidence in Context: Limitations and Open Questions

When to Consult a Doctor

While next-generation mRNA vaccine science continues to advance, patients should consult their healthcare provider in the following circumstances:

• If you are over 60 years of age or have underlying lung disease (COPD, asthma), heart disease, diabetes, or immunosuppression — these groups are at highest risk of severe RSV and influenza disease and should discuss currently available vaccine options promptly.
• If you are a parent of an infant or young child — RSV is the leading cause of acute lower respiratory tract infections in children under five years globally [4], and vaccine guidance is rapidly evolving.
• If you have questions about the durability of your current respiratory vaccines and whether booster doses are recommended for your age group and health profile.
• If you are interested in participation in clinical trials for next-generation mRNA or inhalable respiratory vaccines — your physician or a local academic medical centre can advise on eligibility.

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