Vaccine Info

Beyfortus (Nirsevimab) RSV Antibody

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Last reviewed
September 26, 2022

Beyfortus® (Nirsevimab) RSV Antibody

Beyfortus® (Nirsevimab) (MEDI8897) single-dose is being developed in partnership between AstraZeneca and Sanofi. The first investigational extended half-life monoclonal antibody (mAb) was developed as a passive immunization to prevent lower respiratory tract infections (LRTI) caused by RSV. It is designed to protect infants experiencing their first RSV season and infants with congenital heart disease or chronic lung disease entering their first and second RSV season. Beyfortus provides direct prophylactic protection via an antibody to help prevent LRTI caused by RSV. Nirsevimab binds to the prefusion conformation of the RSV fusion protein

Nirsevimab has been granted regulatory designations to facilitate expedited development by several regulatory agencies, including Breakthrough Therapy Designation by The China Center for Drug Evaluation under the National Medical Products Administration; a Breakthrough Therapy Designation from the U.S. Food and Drug Administration; access granted to the European Medicines Agency PRIority MEdicines scheme; Promising Innovative Medicine designation by the U.K. Medicines and Healthcare products Regulatory Agency, and named "a medicine for prioritized development" under the Project for Drug Selection to Promote New Drug Development in Pediatrics by the Japan Agency for Medical Research and Development.

The NEJM published an Original Article, based on a phase 3 study, on March 3, 2022, that concluded a single injection of nirsevimab administered before the RSV season protected healthy late-preterm and term infants from medically attended RSV-associated lower respiratory tract infection. On May 11, 2022, the companies announced the prespecified pooled analysis from Phase III and Phase IIb trials demonstrated the efficacy of 79.5% against medically attended lower respiratory tract infections, including hospitalizations, caused by RSV. The clinical results of MEDLEY, MELODY, and the Phase 2b clinical trials demonstrate nirsevimab's protective benefits.

The U.S. CDC's ACIP meeting on June 23, 2022, reviewed - Nirsevimab For The Prevention of RSV Disease In All Infants.

The European Medicines Agency (EMA) Committee for Medicinal Products for Human Use (CHMP) adopted on September 16, 2022, a positive opinion for Beyfortus® (nirsevimab) to prevent RSV lower respiratory tract disease in newborns and infants during their first RSV season. If approved, Beyfortus would be the first and only single-dose passive immunization for the broad infant population, including those born healthy, at term or preterm, or with specific health conditions. Beyfortus was supported through EMA's PRIority MEdicines scheme.

PubChem SID: 384585358; ChEMBL: ChEMBL4297575

In March 2017, Sanofi and AstraZeneca announced an agreement to develop and commercialize nirsevimab and share all costs and profits. Sanofi is listed on EURONEXT: SAN and NASDAQ: SNY. AstraZeneca (LSE/STO/Nasdaq: AZN) is a global, science-led biopharmaceutical company. BEYFORTUS - Trademark Details: 90557485.

Beyfortus (Nirsevimab) Indication

Nirsevimab is designed to be administered from birth to infants born during the RSV season or at the season's start for infants entering their first RSV season. RSV is a common, contagious virus that causes seasonal epidemics of LRTI, leading to bronchiolitis and pneumonia in infants. It is also a leading cause of hospitalizations in all infants.

Beyfortus (Nirsevimab) Dosage

Nirsevimab is in phase 3 clinical trials to determine the proper dosage. Monoclonal antibodies do not require the activation of the immune system to help offer rapid and direct protection against disease.

Beyfortus (Nirsevimab) Price

As of September 17, 2022, the commercial price of Beyfortus has not been disclosed. Global RSV-related direct medical costs were estimated at €4.82 billion in 2017. 

Various financial support and discount information is posted at InstantRx™.

Beyfortus (Nirsevimab) Financial News

July 30, 2022 - Sanofi Nirsevimab presentation: Aiming for RSV prophylaxis for all infants.

Beyfortus (Nirsevimab) News For 2017 - 2022

September 16, 2022 - Jean-François Toussaint, Global Head of Research and Development Vaccines, Sanofi, stated: “Today’s positive CHMP opinion is one of the most significant public health achievements in RSV in decades and has the potential to alleviate the enormous physical and emotional burden that RSV can place on families and healthcare systems. With this endorsement, we are one step closer to achieving our goal of protecting all infants against RSV with a single dose.”

August 12, 2022 - Sanofi and the National Institute for Health and Care Research announced that the first patient had been enrolled in the Hospitalised RSV Monoclonal Antibody Prevention (HARMONIE) study, an open-label trial that will evaluate the use of nirsevimab, a passive immunization, in a broad population.

May 11, 2022 - AstraZeneca announced results from a prespecified pooled analysis of the pivotal MELODY Phase III and Phase IIb trials showed AstraZeneca and Sanofi's nirsevimab demonstrated an efficacy (relative risk reduction versus placebo) of 79.5% (95% Confidence Interval [CI] 65.9 to 87.7; P<0.0001) against medically attended lower respiratory tract infections (LRTI), such as bronchiolitis or pneumonia, caused by RSV in infants born at term or preterm entering their first RSV season.

March 3, 2022 - Sanofi announced the New England Journal of Medicine published detailed results from a Phase 3 trial evaluating nirsevimab involving healthy infants born at term or late preterm (35 weeks gestational age or greater) entering their first RSV season and met the primary endpoint, reducing the incidence of medically attended lower respiratory tract infections, such as bronchiolitis or pneumonia, caused by RSV by 74.5% (95% CI 49.6 to 87.1; P<0.001) compared to placebo.

August 11, 2021 - A peer-reviewed study concluded: Based on the mechanism of action of the new generation of anti-viral mAbs, such as nirsevimab, which is highly specific in targeting viral antigenic sites, it is unlikely that it could interfere with the immune response to other vaccines. Taken together, we anticipate that nirsevimab could be concomitantly administered to infants with routine pediatric vaccines during the same clinic visit.

June 28, 2021 - Sanofi announced Nirsevimab shows positive topline results in RSV Phase 2/3 MEDLEY trial.

July 30, 2020 - Sanofi published detailed results from the Phase 2b trial for nirsevimab showing a significant reduction in medically attended lower respiratory tract infections (LRTI), mainly bronchiolitis and pneumonia, and hospitalizations caused by the respiratory syncytial virus (RSV) in healthy preterm infants.

February 5, 2019 - AstraZeneca and its global biologics research and development arm, MedImmune, announced that the U.S. FDA granted Breakthrough Therapy Designation for MEDI8897.

March 3, 2017 - Sanofi Pasteur announced today an agreement with MedImmune, the global biologics research and development arm of AstraZeneca, to develop and commercialize a monoclonal antibody--called MEDI8897--for the prevention of RSV-associated illness in newborns and infants. 

Beyfortus (Nirsevimab) Clinical Trials

Nirsevimab has been tested in several clinical trials.

The Hospitalized RSV Monoclonal Antibody Prevention (HARMONIE) phase 3b randomized open-label study of nirsevimab in preventing hospitalizations due to RSV in infants under 12 months.

A Phase 3 trial is currently recruiting to evaluate the Safety and Efficacy of Nirsevimab in Healthy Preterm and Term Infants in China. (CHIMES) Eight hundred infants are anticipated to participate in this randomized, double-blind, placebo-controlled, single-dose study to determine if nirsevimab will prevent medically attended RSV-confirmed LRTI in healthy preterm and term infants entering their first RSV season. This study is anticipated to be completed at the end of 2025.

 In the MELODY and Phase 2b trials, Beyfortus met its primary endpoint of reducing the incidence of medically attended lower respiratory tract infections (LRTI) caused by RSV during the RSV season vs. placebo with a single dose. 1-6 The safety profile of Beyfortus was similar to placebo. Beyfortus also demonstrated comparable safety and tolerability profile to palivizumab in the Phase 2/3 MEDLEY trial.