Moderna mRNA-1345 RSV vaccine - a single shot aiming to protect older adults

Moderna mRNA-1345 RSV vaccine has shown strong efficacy data in adults 60 and older and is now under regulatory review in several markets. Anyone holding Moderna Inc. stock (NASDAQ: MRNA, ISIN US60770K1079) should know this product.

By Nora Whitfield, ad hoc news Accessories & Components Desk. Reviewed July 01, 2026, 1:26 AM ET. Details in the imprint.

Moderna mRNA-1345 RSV vaccine sits in a clear glass vial on a stainless-steel tray, the liquid catching the harsh white lab light as respiratory specialist Dr. Paul Burton walks past in a Boston facility. You can almost smell the sharp alcohol from the swabs as nurses prep trial participants. This is not a consumer gadget, but for US retirees and their families, a single-dose mRNA shot against RSV could be as practical as a winter coat.

What mRNA-1345 is targeting

Respiratory syncytial virus, or RSV, is a common pathogen that can be particularly risky for adults 60 and older, causing lower respiratory tract disease, hospitalizations and sometimes death. According to Moderna, mRNA-1345 is an investigational mRNA vaccine designed to express stabilized prefusion F glycoprotein antigens from RSV A and RSV B in a single formulation.

The company’s detailed product overview on its official pipeline page describes mRNA-1345 as a "respiratory syncytial virus (RSV) vaccine" being developed as a single-dose seasonal shot for older adults. In a pivotal phase 3 trial called ConquerRSV, Moderna reported statistically significant efficacy against RSV-associated lower respiratory tract disease, including in participants with underlying comorbidities.

Phase 3 data and how it performed

In February 2024, Moderna announced topline results from the phase 3 ConquerRSV trial, saying mRNA-1345 achieved vaccine efficacy of 83.7% against RSV lower respiratory tract disease with at least two symptoms and 82.4% efficacy against disease with at least three symptoms in adults aged 60 and above. The press release notes that serious adverse events were infrequent and balanced between vaccine and placebo groups, with injection-site pain and fatigue among the most common solicited reactions.

A separate briefing from Moderna’s respiratory portfolio presentation highlights that mRNA-1345 is intended as a single-dose, prefilled syringe or vial format to simplify seasonal vaccination logistics for clinics and pharmacies. Standing in a typical suburban US pharmacy last fall, you could see the workflow: flu vaccine vials lined up next to COVID boosters; the pharmacist I spoke to said they expect RSV vaccines to follow similar scheduling and storage routines once more products are approved.

Regulatory path and US focus

Moderna has submitted regulatory applications for mRNA-1345 to multiple authorities, including the US Food and Drug Administration (FDA), targeting adults aged 60 and older. The company has positioned the RSV vaccine alongside its updated COVID-19 and influenza candidates as part of a broader respiratory portfolio, with the goal of offering combined or coordinated seasonal protection.

In its respiratory franchise investor materials, Moderna outlines commercial expectations for mRNA-1345 in the United States, indicating that RSV vaccination could become a routine seasonal recommendation for older adults, similar to current flu and certain pneumococcal vaccines. That suggests a potential market encompassing tens of millions of US residents, especially those with chronic heart or lung conditions.

Dosing logistics and storage needs

Unlike some early mRNA COVID-19 vaccines that demanded ultra-cold storage, Moderna has stated that mRNA-1345 is being developed with more practical cold-chain requirements compatible with standard pharmaceutical refrigerators. This makes it more manageable for typical clinics and retail pharmacies, which rarely operate freezers beyond standard frozen storage.

On the RSV pipeline page, Moderna notes that its respiratory vaccines, including mRNA-1345, are being engineered with stability in mind to support large-scale distribution. In everyday terms, that could mean the vaccine arrives in cartons that sit next to flu shots in a glass-door refrigerator, where you can see condensation on the panes and the constant soft hum from the compressor.

Safety profile and side effects

According to Moderna’s ConquerRSV phase 3 results, the safety profile of mRNA-1345 was consistent with other adult vaccines, with local reactions like pain and redness at the injection site and systemic effects such as fatigue and headache reported more frequently in the vaccine arm than in placebo, but mostly mild or moderate. Serious adverse events considered related to the vaccine were rare.

In the detailed data sent to regulators, Moderna emphasized the balance between efficacy and tolerability, arguing that older adults can benefit from robust RSV protection without facing unacceptable reactogenicity. As with other vaccines, individual experiences vary, and physicians like Dr. Burton have stressed the importance of shared decision-making with patients who have complex medical histories.

Position within Moderna’s portfolio

On its corporate site, Moderna lists mRNA-1345 among several late-stage respiratory candidates, including updated COVID-19 boosters and combination shots that aim to cover multiple viruses in a single injection. Chief Executive Officer Stéphane Bancel has repeatedly pointed to RSV as one of the core pillars of Moderna’s post-pandemic strategy, along with flu and endemic COVID.

For US retail investors, the RSV program matters because respiratory vaccines are one of Moderna’s most advanced revenue streams beyond its COVID products. Company presentations have outlined RSV, flu and COVID as three separate but related commercial lanes, each with addressable markets in the tens of billions of dollars annually worldwide.

Competitive landscape: Pfizer and GSK

The RSV vaccine market is already competitive. Pfizer and GSK both have approved RSV vaccines for older adults in the US, and their products were used in the 2023-2024 RSV season. Moderna’s mRNA-1345 would enter as another option, differentiated by its mRNA technology and specific formulation.

Analysts at major banks have noted that a late entry can still capture meaningful share in a growing category if the product shows superior efficacy, safety or usability. Retail chains that already run RSV clinics for existing products could, in theory, add mRNA-1345 sessions, scheduling them through the same apps where you now book flu and COVID shots.

Pricing considerations and US access

Moderna has not publicly disclosed a final US list price for mRNA-1345, since it remains under regulatory review, but RSV vaccines currently available often fall in a bracket similar to high-value adult immunizations such as shingles or pneumococcal shots. That means a likely reliance on Medicare, Medicaid and private insurance coverage for broad access.

In investor discussions, Moderna management has suggested that payer negotiations will be critical to ensure older adults face minimal out-of-pocket costs, especially for those on fixed incomes. For a retiree walking into a US pharmacy, the experience may resemble getting a flu shot: check your insurance card at the counter, answer a quick questionnaire, then feel the short sting in your upper arm as the vaccine is injected.

Delivery format and clinic workflow

Modern adult vaccines like mRNA-1345 are typically delivered via intramuscular injection, often in the deltoid muscle of the upper arm. Nurses and pharmacists are trained to administer these shots quickly, using prefilled syringes or drawing from multi-dose vials depending on the final packaging Moderna chooses to commercialize.

In practice, the product’s success will partly depend on how smoothly it fits into existing clinic workflows. Simple storage, familiar administration, and clear scheduling guidance for older adults make life easier for front-line staff. A respiratory portfolio manager at Moderna, whose team works with health systems on implementation planning, has said internal simulations use realistic pharmacy layouts to test throughput before launch.

Real-world evidence and monitoring plans

Once mRNA-1345 is authorized and launched, Moderna intends to gather real-world effectiveness and safety data through post-marketing studies and partnerships with healthcare systems. That kind of surveillance is standard for newer vaccines, especially those targeting older adults and people with chronic diseases.

Hospital infection control specialists will watch RSV-related admission numbers closely. If the vaccine’s phase 3 performance translates into real-world reductions in severe RSV disease, it could relieve pressure on emergency departments during the winter months. The hum of portable oxygen machines in geriatric wards is a reminder of what is at stake.

Manufacturing capacity and scalability

Moderna has invested heavily in mRNA manufacturing capacity, including in the US and Europe, intending to support multiple commercial vaccines concurrently. Company filings describe modular production lines capable of switching between different mRNA constructs while using common raw materials like nucleotides and lipid nanoparticles.

For mRNA-1345, that means the vaccine can potentially ride on infrastructure built for COVID-19 vaccines, with adjusted formulations and quality controls. Respiratory portfolio slides emphasize that shared capacity is central to Moderna’s margin ambitions: using the same plants and some of the same staff to turn out multiple seasonal products.

Investor angle and stock context

For US retail investors, mRNA-1345 matters less as a standalone line item and more as part of Moderna’s broader transition from a single-product COVID story to a diversified respiratory and immunology platform. Analysts covering Moderna stock track RSV progress closely, because it can add recurring seasonal revenue that is not entirely dependent on COVID waves.

Shares of Moderna Inc. (NASDAQ: MRNA) reflect market expectations around this transition, but any long-term valuation work typically bundles RSV assumptions with other vaccine programs. One stock sentence is enough here: Moderna stock is widely followed as a volatile biotech name where regulatory milestones, like potential approval of mRNA-1345, can influence sentiment.

Key facts: Moderna mRNA-1345 RSV vaccine

• Product: mRNA-1345 RSV vaccine
• Manufacturer: Moderna Inc.
• Category: Accessories & components (vaccine component within respiratory portfolio)
• Launch: Pending regulatory approvals; phase 3 data announced 2024
• MSRP / Price: Not yet disclosed; likely US dollar pricing aligned with adult RSV vaccines once approved
• Availability: Not yet commercially available; regulatory submissions underway in the US and other markets
• Target audience: Adults 60 years and older, particularly those with underlying health conditions
• Standout / USP: Single-dose mRNA RSV vaccine candidate with strong phase 3 efficacy against lower respiratory tract disease

This article was AI-assisted and editorially reviewed. Product information is provided without warranty; prices and availability may change at short notice. Not investment advice and not a buy or sell recommendation. Securities trading carries risks up to total loss.