mRNA Vaccines and Clinical Trials: The Latest Research in 2026

mRNA vaccine clinical trials have expanded dramatically since 2020. What began as a rapid-response technology for the COVID-19 pandemic has now become the foundation for one of the most active research frontiers in medicine. In 2026, dozens of programs are running simultaneously across influenza, RSV, cancer, and other infectious diseases — each using the same core platform that made COVID-19 vaccines possible in record time.

This article covers the latest mRNA vaccine research, explains how clinical trials work for these vaccines, and reviews where the most significant programs currently stand — including the mRNA cancer vaccine trials that could fundamentally change how oncology treats solid tumors.

What Are mRNA Vaccines?

mRNA vaccines work by delivering a short sequence of messenger RNA into the body. That RNA gives cells temporary instructions for producing a specific antigen — a protein that the immune system can recognize and respond to. Once the immune system has been trained, it can mount a faster and stronger defense if it encounters the actual pathogen or, in the case of cancer vaccines, cells displaying those same markers.

Importantly, mRNA does not enter the cell nucleus and cannot alter DNA. The mRNA degrades naturally within days of injection. This makes it a fundamentally different platform from older vaccine technologies, which typically use weakened or inactivated pathogens, or protein subunits, to achieve a similar immune training effect.

The central advantage of mRNA technology is speed and adaptability. Once a target antigen is identified, a new mRNA sequence can be designed and manufactured relatively quickly. This is why mRNA platforms were the first to deliver authorized COVID-19 vaccines and why researchers are now applying the same approach to diseases that have resisted effective vaccines for decades.

What Is Happening in mRNA Vaccine Clinical Trials?

As of 2026, mRNA vaccine clinical trials are being conducted across a broad range of disease areas. The pipeline includes programs in late-stage Phase 3 trials, mid-stage Phase 2 trials, and early safety studies. Moderna, BioNTech, Pfizer, and Merck are among the most active sponsors, alongside academic institutions including the National Cancer Institute and universities conducting investigator-initiated studies.

Clinical trials for mRNA vaccines follow the same phase structure used for all vaccine and drug development. Phase 1 studies primarily assess safety and dosing in a small group of volunteers. Phase 2 expands to hundreds of participants to evaluate immune response and side effect profiles more comprehensively. Phase 3 trials enroll thousands of participants to assess real-world efficacy and rare adverse events. Additionally, regulatory submissions follow the Phase 3 data, leading to review by agencies such as the U.S. Food and Drug Administration.

Disease Area	Key Programs	Current Stage
Influenza	Moderna mRNA-1010, mRNA-1020	Phase 3
RSV	Moderna mResvia (mRNA-1345)	FDA Approved (adults 60+)
Cancer (Melanoma)	Moderna/Merck mRNA-4157 (V940)	Phase 3
Cytomegalovirus	Moderna mRNA-1647	Phase 3
Norovirus	Moderna mRNA-1403	Phase 2
HIV	Multiple research programs	Phase 1/2

mRNA Flu Vaccines Enter a New Phase

Influenza vaccination has relied on egg-based or cell-based manufacturing for decades. However, that process is slow and requires manufacturers to predict which strains will circulate months before flu season begins. When the prediction misses, vaccine effectiveness can drop sharply. The mRNA flu vaccine approach addresses this problem directly.

Moderna’s mRNA-1010 is a quadrivalent influenza vaccine candidate targeting four influenza strains simultaneously. Phase 3 clinical trials have enrolled tens of thousands of participants across multiple countries. Early data demonstrated robust immune responses across all four target strains and a favorable safety profile consistent with other mRNA vaccines. Furthermore, because mRNA flu vaccines can be reformulated and manufactured faster than conventional approaches, they could allow manufacturers to respond to unexpected strain changes in a matter of weeks rather than months.

Moderna has also advanced mRNA-1020, a next-generation influenza candidate designed to offer broader coverage across a wider range of influenza A strains. This program reflects a longer-term ambition: developing a more universal flu vaccine that does not require annual reformulation. Phase 2 data from this program has informed the design of Phase 3 protocols.

In contrast to traditional flu vaccines, mRNA platforms also allow combination vaccines that cover multiple respiratory viruses in a single injection. Moderna has disclosed development work on mRNA combination vaccines targeting influenza, COVID-19, and RSV together — a single-shot approach that could significantly simplify annual respiratory vaccination.

mRNA Vaccines and RSV Research

Respiratory syncytial virus (RSV) causes severe respiratory illness, particularly in adults over 60 and infants. For decades, despite significant investment, an effective RSV vaccine remained out of reach. mRNA technology changed that. In 2024, the U.S. FDA approved Moderna’s mRNA-1345 — marketed as mResvia — for adults aged 60 and older, making it the first authorized mRNA vaccine for a disease other than COVID-19.

mResvia targets the RSV prefusion F protein, the same structural target used by other approved RSV vaccines. Phase 3 trial data showed that mResvia reduced the risk of RSV-associated lower respiratory tract disease in adults 60 and over. The trial enrolled over 35,000 participants across multiple countries and demonstrated a consistent safety profile.

Moreover, the RSV approval validated a key assumption underlying the broader mRNA vaccine research agenda: that the platform was not a one-time solution for an emergency, but a reusable technology applicable to pathogens that have been difficult to target with traditional vaccines. Consequently, the RSV milestone accelerated regulatory and investor confidence in mRNA programs across the pipeline.

How mRNA Cancer Vaccines Could Change Cancer Treatment

The most consequential frontier in mRNA vaccine research is cancer. Unlike infectious disease vaccines that train the immune system to recognize a foreign pathogen, mRNA cancer vaccines train it to recognize tumor-specific markers — antigens expressed on cancer cells that differ from healthy tissue. This approach, known as cancer immunotherapy, has been theorized for decades. mRNA technology is now making it clinically feasible at scale.

The most advanced program is mRNA-4157, developed by Moderna in partnership with Merck. Also known as V940, this is a personalized cancer vaccine designed specifically for each individual patient. Tumor biopsy material is sequenced to identify neoantigens — mutations unique to that patient’s cancer — and an mRNA sequence encoding up to 34 of those neoantigens is manufactured and administered alongside Merck’s checkpoint inhibitor Keytruda (pembrolizumab).

Phase 2b results from the KEYNOTE-942 trial were striking. Patients with high-risk melanoma who received mRNA-4157 plus Keytruda after surgical resection showed a 49% reduction in the risk of recurrence or death compared to patients who received Keytruda alone. For a disease where recurrence after surgery remains a major clinical challenge, this result drew widespread attention from oncologists and researchers.

As a result of those findings, a Phase 3 trial — KEYNOTE-P1 — was initiated. The Phase 3 program is studying mRNA-4157 plus Keytruda in resected high-risk melanoma, and it includes plans to expand into non-small cell lung cancer and other solid tumor types if Phase 3 results confirm the Phase 2b benefit signal.

How Do mRNA Cancer Vaccine Clinical Trials Work?

mRNA cancer vaccine clinical trials follow the same three-phase framework as infectious disease vaccine trials, but with important differences in design. Because personalized cancer vaccines are unique to each patient, the manufacturing process itself must be validated alongside the clinical evidence. Each participant effectively receives a different product, sequenced from their own tumor.

In practice, this means that early trials must establish not only safety and immune response, but also the feasibility of the full personalized manufacturing pipeline — from biopsy to sequencing to mRNA synthesis to delivery within a clinically meaningful timeframe. Early Phase 1 studies in melanoma established that the end-to-end turnaround could be achieved in approximately three to four weeks for most patients, a timeline considered viable for adjuvant treatment after surgery.

Furthermore, cancer vaccine trials typically measure different endpoints than infectious disease vaccine trials. Rather than prevention of infection, the primary endpoints are often recurrence-free survival, overall survival, or tumor response rates. These endpoints require longer follow-up periods, which is why definitive Phase 3 data from programs like KEYNOTE-P1 is expected to take several years to mature fully.

Why Phase 3 Clinical Trials Matter

Phase 3 trials are the final and most rigorous step before a vaccine can be submitted for regulatory approval. They enroll large numbers of participants — typically tens of thousands — to detect efficacy signals and rare side effects that earlier trials may miss. For mRNA vaccine clinical trials, Phase 3 represents the point at which a promising research program must demonstrate real-world impact at population scale.

In contrast to Phase 1 and Phase 2, which are designed primarily for safety and dose-finding, Phase 3 trials are powered statistically to answer a specific question with high confidence: does this vaccine reduce disease in a way that is clinically meaningful? Regulatory agencies including the FDA and the European Medicines Agency evaluate both the magnitude of the benefit and the safety data before issuing authorization.

For the mRNA flu and cancer vaccine programs currently in Phase 3, the results of these trials will determine whether the technology’s promise translates into widespread clinical use. Therefore, the next two to four years represent the most important evidentiary period in the history of post-COVID mRNA vaccine development.

What Diseases Are mRNA Vaccines Being Developed For?

The breadth of diseases currently being targeted by mRNA vaccines has expanded significantly since 2021. The following diseases represent active programs with published clinical trial data or announced research partnerships as of 2026.

• Influenza: Moderna’s mRNA-1010 and mRNA-1020 are in Phase 3 and Phase 2 respectively, targeting quadrivalent seasonal flu and broader strain coverage.
• RSV: Moderna’s mResvia (mRNA-1345) received FDA approval for adults 60 and over in 2024, the first authorized non-COVID mRNA vaccine.
• Melanoma: Moderna and Merck’s mRNA-4157 (V940) is in Phase 3 for high-risk resected melanoma in combination with Keytruda.
• Non-small cell lung cancer: mRNA-4157 expansion studies are planned or underway based on melanoma Phase 2b results.
• Cytomegalovirus (CMV): Moderna’s mRNA-1647 is in Phase 3. CMV is a leading infectious cause of birth defects, making this program a significant public health priority.
• Norovirus: Moderna’s mRNA-1403 is in Phase 2 targeting norovirus gastroenteritis, a disease that causes approximately 685 million cases annually worldwide.
• HIV: Multiple research groups are exploring mRNA approaches to HIV, including programs designed to generate broadly neutralizing antibodies. These remain in early Phase 1 and 2 stages.
• Tuberculosis: mRNA-based TB vaccines are at preclinical and early clinical stages, supported by global health funding from organizations including the Bill and Melinda Gates Foundation.

Challenges Facing mRNA Vaccine Research

Despite the momentum, mRNA vaccine research faces real scientific, manufacturing, and regulatory challenges that will shape how quickly programs move from clinical trials to widespread use.

Cold chain requirements. mRNA vaccines require cold storage, and some early formulations required ultra-cold temperatures that complicated distribution. However, newer lipid nanoparticle formulations have improved stability at standard refrigerator temperatures. This remains an active area of formulation research, particularly for programs targeting lower-income countries where cold chain infrastructure is limited.

Immune response durability. A recurring question in mRNA flu and RSV research is how long immune protection lasts. COVID-19 mRNA vaccines demonstrated that protection against severe disease was durable, but protection against infection waned more quickly. For seasonal respiratory viruses like influenza, durable protection is essential to avoid the need for very frequent boosting. Moreover, this question is central to how regulators will evaluate the long-term benefit profile of mRNA flu vaccines versus existing alternatives.

Personalized manufacturing at scale. For cancer vaccines, the manufacturing challenge is significant. Each personalized vaccine requires tumor sequencing, neoantigen selection by algorithm, mRNA synthesis, quality testing, and delivery within a tight clinical window. Scaling this process while maintaining consistency and turnaround time is a major operational undertaking that has no precedent in pharmaceutical manufacturing history.

Public perception. Although COVID-19 vaccines significantly raised public awareness of mRNA technology, they also generated skepticism and misinformation in some communities. Addressing this through clear, accessible scientific communication is a challenge that extends beyond clinical research into public health communication and trust-building.

What Is Next for mRNA Vaccine Technology?

The direction of mRNA vaccine research over the next decade points toward three converging trends: combination vaccines, self-amplifying mRNA, and expanded therapeutic applications.

Combination vaccines that cover multiple respiratory viruses — influenza, COVID-19, and RSV — in a single shot are already in development. Moderna has disclosed plans for a combination mRNA product targeting all three viruses simultaneously. This would streamline annual respiratory vaccination and potentially improve uptake by reducing the number of separate injections required.

Self-amplifying mRNA (sa-mRNA) is a next-generation formulation that encodes replication machinery alongside the antigen sequence. This allows a much smaller dose of mRNA to produce a larger and more sustained immune response. Japan authorized the world’s first sa-mRNA vaccine (ARCT-154, developed by Arcturus Therapeutics) for COVID-19 in 2023, establishing regulatory precedent. Additionally, several research programs are now testing sa-mRNA in other disease areas.

Therapeutic applications beyond vaccines are also in development. mRNA is being studied as a delivery mechanism for cancer immunotherapy beyond vaccines, for protein replacement therapies in rare genetic diseases, and for in vivo gene editing. These programs extend the platform’s potential well beyond infectious disease prevention and represent a long-term growth area for the broader mRNA field.

Frequently Asked Questions About mRNA Vaccines