BEYFORTUS Drug Profile

Summary for Tradename: BEYFORTUS

High Confidence Patents:	0
Applicants:	2
BLAs:	1

Pharmacology for BEYFORTUS

Mechanism of Action	Fusion Protein Inhibitors
Established Pharmacologic Class	Respiratory Syncytial Virus Anti-F Protein Monoclonal Antibody

Note on Biologic Patents

Matching patents to biologic drugs is far more complicated than for small-molecule drugs.

DrugPatentWatch employs three methods to identify biologic patents:

1. Brand-side disclosures in response to biosimilar applications

These patents were identified from disclosures by the brand-side company, in response to a potential biosimilar seeking to launch. They have a high certainty of blocking biosimilar entry. The expiration dates listed are not estimates — they're expiration dates as indicated by the brand-side company.

2. DrugPatentWatch analysis and company disclosures

These patents were identified from searching various sources, including drug labels and other general disclosures from the brand-side company. This list may exclude some of the patents which block biosimilar launch, and some of these patents listed may not actually block biosimilar launch. The expiration dates listed for these patents are estimates, based on the grant date of the patent.

3. Patents from broad patent text search

For completeness, these patents were identified by searching the patent literature for mentions of the branded or ingredient name of the drug. Some of these patents protect the original drug, whereas others may protect follow-on inventions or even inventions casually mentioning the drug. The expiration dates listed for these patents are estimates, based on the grant date of the patent.

1) High Certainty: US Patents for BEYFORTUS Derived from Brand-Side Litigation

No patents found based on brand-side litigation

2) High Certainty: US Patents for BEYFORTUS Derived from DrugPatentWatch Analysis and Company Disclosures

No patents found based on company disclosures

3) Low Certainty: US Patents for BEYFORTUS Derived from Patent Text Search

No patents found based on company disclosures

Beyfortus Market Dynamics, Financial Trajectory, Patent Exclusivity and Competitive Outlook

Last updated: September 8, 2026

Beyfortus, the brand name for nirsevimab, has become the leading new commercial product in the infant respiratory syncytial virus, or RSV, prevention market. Sanofi and AstraZeneca launched the long-acting monoclonal antibody after FDA approval in July 2023 and expanded distribution through public-health purchasing programs. Reported Sanofi sales increased from approximately €550 million in 2023 to roughly €1.3 billion in 2024, driven by wider U.S. uptake and stronger seasonal supply.

The commercial outlook depends on four factors: annual birth cohorts, U.S. government procurement, competition from maternal RSV vaccination, and the timing of biosimilar or follow-on antibody entry. Beyfortus has no traditional generic pathway because it is a biologic. Its U.S. regulatory exclusivity runs substantially longer than its initial launch period, while patent protection and manufacturing complexity may extend practical market protection.

What is Beyfortus and how does it work?

Beyfortus is a recombinant human immunoglobulin G1 monoclonal antibody that targets the prefusion F protein of RSV. Its active ingredient, nirsevimab-alip, neutralizes RSV before the virus infects airway cells.

Unlike palivizumab, which generally requires monthly administration during the RSV season, Beyfortus is designed to provide protection with a single intramuscular dose for most infants entering their first RSV season. The longer half-life is enabled by an Fc-region modification that extends antibody persistence.

Product	Active ingredient	Primary use	Typical administration	Commercial sponsor
Beyfortus	Nirsevimab	RSV prevention in infants and certain high-risk children	One dose per RSV season	Sanofi and AstraZeneca
Synagis	Palivizumab	RSV prevention in selected high-risk pediatric patients	Monthly injections during RSV season	AstraZeneca
Abrysvo	RSV prefusion F vaccine	Maternal immunization and older adults	Maternal vaccination during pregnancy	Pfizer
Arexvy	RSV prefusion F vaccine	Adults aged 60 and older	Adult vaccination	GSK

Beyfortus is a passive-immunization product. Abrysvo is an active maternal vaccination product. The two approaches compete for protection of infants but are not clinically interchangeable in all circumstances.

What is the FDA regulatory status of Beyfortus?

The FDA approved Beyfortus on July 17, 2023. The approved U.S. indication covers:

• Neonates and infants born during or entering their first RSV season.
• Children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season.

The U.S. Centers for Disease Control and Prevention and its Advisory Committee on Immunization Practices recommended a single dose for infants younger than eight months entering their first RSV season when maternal vaccination was not received, was administered too recently to provide adequate passive protection, or was otherwise not expected to provide sufficient protection. Certain high-risk children aged eight through 19 months are eligible for a dose before their second RSV season.[3]

The product is distributed through several reimbursement channels, including commercial insurance, Medicaid, and the Vaccines for Children program. Public-sector purchasing has been central to access because administration occurs in hospitals, pediatric practices, pharmacies, and other clinical settings rather than through a conventional retail prescription model.

What are the approved Beyfortus doses?

Infant or child weight	Dose	Presentation
Less than 5 kg	50 mg	Single intramuscular dose
At least 5 kg	100 mg	Single intramuscular dose
Certain high-risk children entering a second RSV season	200 mg total	Two 100 mg injections

The most important commercial limitation is seasonal demand. Manufacturers and health systems must align inventory with the U.S. RSV season, which usually begins in the fall but varies by geography and year.

How much revenue does Beyfortus generate?

Sanofi’s reported Beyfortus revenue increased sharply after the initial 2023 launch.

Fiscal year	Approximate Beyfortus sales	Commercial interpretation
2023	€0.55 billion	Partial launch year, constrained by seasonality and initial supply
2024	Approximately €1.3 billion	Full-season U.S. contribution and broader international uptake
2025 outlook	Dependent on seasonal procurement	Growth depends on birth cohorts, government contracts, supply and maternal-vaccine use

The 2023 figure reflects only part of the launch cycle. Sanofi entered the U.S. market shortly before the 2023-2024 RSV season, when supply constraints limited availability in some locations. The 2024 sales base benefited from a more established distribution network and greater health-system familiarity.

Beyfortus has become one of Sanofi’s most important growth products within its vaccines business. Its revenue profile is different from that of chronic-care medicines because much of the annual demand is concentrated in a few months. A strong season can produce a large fourth-quarter contribution, while inventory timing can shift revenue between quarters or fiscal years.

What drives the Beyfortus market?

U.S. birth cohorts and RSV seasonality

The U.S. market is anchored to approximately 3.5 to 4 million annual births. The addressable first-season population is large, but actual treated volume depends on:

• Maternal RSV vaccination rates.
• Pediatrician and hospital adoption.
• Medicaid and Vaccines for Children coverage.
• Seasonal timing.
• Reimbursement and administration economics.
• Parent acceptance of an injection for an otherwise healthy infant.

The product can reach a broader infant population than Synagis because it is not limited to the narrowest high-risk groups. That broader eligibility creates a much larger revenue opportunity but also creates greater exposure to procurement bottlenecks.

Government purchasing

Government purchasing is a major commercial accelerator. In the United States, the Vaccines for Children program can provide Beyfortus to eligible children without direct product cost to families. Medicaid coverage is also important because Medicaid finances a large share of U.S. births.

Government contracts can support rapid volume expansion but may pressure net pricing. The commercial value of each dose depends on the mix between private-sector sales, Medicaid reimbursement, public contracts and distributor discounts.

International uptake

The European Commission authorized Beyfortus in October 2022. European market access is controlled by national reimbursement decisions and centralized or regional procurement. Pricing is generally more constrained than in the U.S., but national immunization programs can create predictable seasonal demand.

Japan and other markets contribute to geographic diversification. The main international risks are delayed reimbursement decisions, country-specific procurement cycles and differences in RSV-season timing.

How does Beyfortus compare with Synagis and maternal RSV vaccines?

Beyfortus has a broader pediatric market than Synagis, but it faces competitive substitution from maternal vaccination.

Competitive factor	Beyfortus	Synagis	Maternal RSV vaccination
Biological approach	Passive monoclonal antibody	Passive monoclonal antibody	Active maternal immunization
Infant dosing	Usually one dose	Monthly dosing	No infant injection if effective maternal antibodies transfer
Target population	Broad infant population plus selected high-risk children	Narrow high-risk pediatric population	Pregnant patients within specified gestational window
Main sponsor	Sanofi and AstraZeneca	AstraZeneca	Pfizer with Abrysvo
Key commercial risk	Seasonal execution and vaccine substitution	Narrow eligibility and administration burden	Maternal acceptance and prenatal-care coverage

Maternal vaccination is the most direct competitive threat because a vaccinated mother may reduce the need for infant antibody administration. The two products can also coexist. Beyfortus remains relevant when maternal vaccination was not given, was given outside the recommended window, or is not expected to provide sufficient protection.

The likely market structure is segmented rather than winner-take-all. Maternal vaccination may dominate in patients with consistent prenatal care, while Beyfortus may have stronger use in hospitals, infants born during the RSV season and populations with lower prenatal vaccination rates.

When does Beyfortus lose exclusivity?

Beyfortus has several separate protection layers. They should not be treated as one expiration date.

Protection category	Estimated timing	Significance
FDA biologic reference-product exclusivity	Through approximately July 2035	A 12-year period from first licensure under the Biologics Price Competition and Innovation Act
EU regulatory protection	Data exclusivity generally through 2030, with market protection potentially through 2032	Depends on European regulatory rules and qualifying indications
Patent protection	Patent-family dependent	Could extend beyond or differ from regulatory exclusivity
Orphan exclusivity	Not the principal protection mechanism for the broad infant indication	The main commercial protection is biologic exclusivity, patents and manufacturing know-how

The FDA does not grant a conventional small-molecule generic pathway for Beyfortus. A competitor would generally need to pursue a biosimilar application under section 351(k) of the Public Health Service Act. A biosimilar application cannot be approved for commercial marketing before the applicable reference-product exclusivity period expires.

The July 2035 estimate is based on the standard 12-year U.S. reference-product exclusivity period measured from the original biologic license approval. Patent-term adjustments, pediatric extensions and litigation outcomes can affect actual market-entry timing.

What is the Orange Book status of Beyfortus?

Beyfortus is not an Orange Book product in the same manner as a conventional small-molecule drug. The Orange Book primarily records approved drug products and patent information relevant to abbreviated new drug applications. Biologic reference products are tracked through the FDA Purple Book.

As a result:

• A conventional Paragraph IV certification is not the standard challenge route.
• A generic-equivalent filing under section 505(j) is not available.
• Biosimilar applicants would use the section 351(k) pathway.
• Patent disputes would generally be handled under the BPCIA patent-exchange and litigation framework, depending on the applicant’s approach.

Publicly reported information does not indicate an approved Beyfortus biosimilar or a major active BPCIA litigation campaign against the product.

What patents protect Beyfortus?

Beyfortus is protected by a layered biologic patent estate rather than one simple composition-of-matter patent. Relevant categories include:

1. Antibodies that bind the RSV prefusion F protein.
2. Specific antibody sequences and binding epitopes.
3. Fc-engineered antibodies with extended half-life.
4. Pharmaceutical compositions and liquid formulations.
5. Methods of preventing RSV infection or severe RSV disease.
6. Cell lines, expression systems and manufacturing processes.
7. Dosing regimens for infants and high-risk pediatric populations.

The core technology originated in AstraZeneca’s biologics research organization, including MedImmune-related patent assets. Sanofi’s commercial rights were obtained through the companies’ collaboration for nirsevimab development and commercialization.

Patent strength is highest where claims cover the antibody sequence, a defined epitope and the Fc modification in combination. Method-of-use patents are generally more vulnerable to non-infringing labels or alternative clinical protocols than composition claims. Manufacturing patents can still create meaningful entry barriers because a biosimilar sponsor must establish a commercially scalable and analytically comparable process.

Exact enforceability depends on claim scope, prosecution history, terminal disclaimers, patent-term adjustments, validity challenges and the jurisdiction involved. Patent expiry therefore cannot be reduced to the FDA exclusivity date.

What licensing deal governs Beyfortus?

Sanofi and AstraZeneca entered their nirsevimab collaboration in 2017. Sanofi assumed responsibility for development and commercialization, while AstraZeneca retained economic participation through upfront, milestone and sales-related payments.

Publicly described commercial terms included:

• An upfront payment reported at approximately €120 million.
• Potential development and regulatory milestones reported at up to approximately €1.5 billion.
• Additional sales-related payments to AstraZeneca.

The agreement gives Sanofi a major commercial role but leaves AstraZeneca economically exposed to global product performance. The structure also aligns AstraZeneca with Sanofi’s investment in manufacturing capacity, regulatory expansion and market access.

Which companies are challenging Beyfortus?

The principal competitive pressures come from product classes rather than named biosimilar entrants.

Pfizer

Pfizer’s Abrysvo competes through maternal immunization. Its market share depends on prenatal vaccination rates, physician recommendation, payer coverage and patient acceptance.

AstraZeneca’s Synagis

Synagis remains relevant for selected high-risk children and has an established reimbursement base. Its monthly dosing schedule makes it less competitive for broad infant prevention, but it remains an important comparator and legacy product.

Potential biosimilar developers

No major approved Beyfortus biosimilar was identified in the public regulatory record used for this assessment. Potential entrants would face:

• The U.S. reference-product exclusivity period.
• Complex analytical characterization.
• Clinical and immunogenicity requirements.
• Seasonal manufacturing and inventory planning.
• Possible composition, formulation and process patents.
• A market with a strong incumbent and government procurement contracts.

What patent litigation affects Beyfortus?

No major publicly reported U.S. patent litigation involving Beyfortus was identified as a current commercial constraint. The absence of Paragraph IV cases is expected because Beyfortus is a biologic, not a small-molecule drug listed in the Orange Book.

Future disputes could arise through:

• BPCIA patent litigation involving a biosimilar applicant.
• Patent challenges to antibody sequence or epitope claims.
• Inter partes review or post-grant validity proceedings.
• Manufacturing-process disputes.
• European opposition or revocation proceedings.

The litigation risk is currently lower than the commercial execution risk. Supply, reimbursement and maternal-vaccine substitution have greater near-term impact on revenue.

How strong is the Beyfortus patent estate?

The estate is commercially strong through the combination of regulatory exclusivity, biologic complexity and manufacturing know-how. Its weakest area is the possibility that a later entrant could design around narrow method-of-use or formulation claims while relying on a separate manufacturing process.

Estate component	Relative strength	Business effect
FDA biologic exclusivity	High	Blocks biosimilar approval before the statutory period ends
Antibody sequence claims	Potentially high	Can restrict close biological substitutes
Epitope claims	Medium to high	Depends on claim breadth and validity
Fc-engineering claims	High if product-specific	Can complicate design-around strategies
Formulation claims	Medium	May be avoided through alternative excipients or presentations
Method-of-use claims	Medium	Can be limited by labeling and clinical-use distinctions
Manufacturing claims	Medium to high	Creates process and comparability barriers

What generic or biosimilar entry risks exist?

Traditional generic entry risk is negligible because Beyfortus is a biologic. Biosimilar risk is a longer-term issue, likely becoming more relevant in the 2030s.

A biosimilar competitor would need to prove high similarity to nirsevimab in structure, activity, pharmacokinetics and immunogenicity. It would also need to navigate seasonal demand. A product entering after the 2035 U.S. exclusivity date could still face patent litigation and a difficult commercial launch if Sanofi has established government contracts and pediatric-provider relationships.

The most credible earlier erosion mechanism is therapeutic substitution by maternal RSV vaccination, not a biosimilar.

What is the Beyfortus generic launch scenario?

The most likely entry sequence is:

1. Continued Sanofi-led expansion through the 2020s.
2. Increasing competition from maternal vaccination during the current decade.
3. Patent and regulatory challenges as the U.S. exclusivity date approaches.
4. Potential biosimilar launches after the statutory reference-product exclusivity period, subject to patent outcomes.
5. Price erosion that is initially moderate because seasonal immunization programs and public procurement can support volume.

A rapid, deep generic-style price collapse is less likely than gradual competitive erosion. The product’s value depends on prevention of hospitalization and infant disease, while the supply chain depends on seasonal public-health planning.

What is the long-term revenue outlook for Beyfortus?

Beyfortus has the potential to remain a multibillion-euro annual product if it achieves high penetration across U.S. and European infant populations. The revenue ceiling is constrained by:

• Maternal RSV vaccine uptake.
• Public-sector pricing.
• Birth-rate trends.
• Seasonal supply execution.
• Duration of infant-protection recommendations.
• Potential use of alternative antibody products.
• Biosimilar entry after regulatory exclusivity.

Sanofi’s strongest growth period is likely to occur while the product is expanding from a new launch into routine seasonal immunization. After broad adoption, growth should depend more on price, geographic expansion, high-risk second-season use and share relative to maternal vaccination.

Key Takeaways

• Beyfortus is Sanofi’s major RSV prevention growth product and generated approximately €1.3 billion in 2024 sales after roughly €550 million in 2023.
• The United States is the largest near-term commercial driver because of its large birth cohort, CDC recommendations and government purchasing programs.
• Maternal RSV vaccination is the main competitive threat, while Synagis remains a narrower legacy competitor.
• Beyfortus is tracked as a biologic through the FDA Purple Book, not through a standard Orange Book generic pathway.
• U.S. reference-product exclusivity is expected to extend to approximately July 2035.
• No major active Paragraph IV or biosimilar litigation campaign is publicly associated with Beyfortus.
• The patent estate covers antibody sequences, epitopes, Fc engineering, formulations, uses and manufacturing processes.
• Near-term revenue risk is driven more by seasonal execution, reimbursement and maternal-vaccine substitution than by generic entry.
• Long-term biosimilar entry is possible after regulatory exclusivity, but manufacturing complexity and patent litigation may delay or moderate erosion.

FAQs

Is Beyfortus a vaccine?

No. Beyfortus is a long-acting monoclonal antibody that provides passive immunity. It does not stimulate the infant’s immune system in the same way as a vaccine.

Can Beyfortus be given after a mother receives an RSV vaccine?

In some circumstances, yes. CDC guidance focuses on whether maternal vaccination was timely and expected to provide adequate infant protection. Beyfortus may be used when maternal vaccination was not received or is not expected to provide sufficient protection.

Is Beyfortus covered by Medicaid?

Beyfortus can be covered through Medicaid and the Vaccines for Children program, subject to applicable eligibility, administration and state or program requirements.

Will a generic version of Beyfortus be available?

A conventional generic is not expected because Beyfortus is a biologic. A biosimilar could be developed under the FDA’s 351(k) pathway after reference-product exclusivity and applicable patent barriers expire.

Who owns Beyfortus?

Sanofi commercializes Beyfortus under its collaboration with AstraZeneca. AstraZeneca originated the antibody program and retains economic rights under the collaboration agreement.

References

1. AstraZeneca. (2017). AstraZeneca and Sanofi enter agreement to develop and commercialise MEDI8897 for the prevention of RSV disease in infants.
2. European Medicines Agency. (2022). Beyfortus: EPAR and product information.
3. U.S. Food and Drug Administration. (2023). FDA approves new drug to prevent respiratory syncytial virus disease in infants and young children.
4. U.S. Food and Drug Administration. (2023). Beyfortus prescribing information.
5. U.S. Centers for Disease Control and Prevention. (2023). Use of nirsevimab for the prevention of respiratory syncytial virus disease among infants and young children: Recommendations of the Advisory Committee on Immunization Practices. MMWR, 72(34), 920-925.
6. Sanofi. (2024). Universal Registration Document and annual financial report 2024.
7. U.S. Food and Drug Administration. (2025). Purple Book: Database of licensed biological products.