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Icosavax, Inc. today announced the U.S. Food and Drug Administration (FDA) has granted Fast Track designation for IVX-A12, a bivalent respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) virus-like particle (VLP) vaccine candidate, in older adults 60 years of age and above.

Niranjan Kanesa-thasan, Chief Medical Officer of Icosavax, commented in a press release on February 21, 2023, "IVX-A12 is differentiated as the most advanced vaccine candidate against these two leading causes of pneumonia in older adults."

In October 2022, Icosavax initiated a Phase 1, randomized, observer-blinded, placebo-controlled, multicenter study of IVX-A12, with and without CSL Seqirus' proprietary adjuvant MF59®, in up to 120 healthy older adults aged 60 to 75 years.

Icosavax anticipates announcing topline interim results from this Phase 1 trial in mid-2023, with subjects after that followed through 12 months after vaccination.

The company plans to initiate a Phase 2 trial for IVX-A12 in the second half of 2023.

According to the FDA, Fast Track is a process designed to facilitate the development and expedite the review of investigational drugs to treat serious conditions and fulfill an unmet medical need. An investigational drug that receives Fast Track designation may be eligible for more frequent interactions with the FDA to discuss the candidate's development plan and, if relevant criteria are met, eligibility for Accelerated Approval and Priority Review.

As of February 21, 2023, the FDA has not approved any RSV vaccine candidates conducting late-stage studies. Furthermore, the FDA has approved and is reviewing RSV monoclonal antibody therapies.

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RSV Monoclonal Antibody

Respiratory Syncytial Virus (RSV) Monoclonal Antibody Therapy 2025

According to the U.S. Centers for Disease Control and Prevention (CDC), respiratory syncytial virus (RSV) is a leading cause of respiratory disease in infants and young children. The European Medicines Agency (EMA) and the CDC say RSV monoclonal antibody (mAb) therapy prevents serious lower respiratory tract disease (LRTD) caused by RSV in newborns and young children during their first RSV season. In 2024, the World Health Organization (WHO) published its preferred product characteristics for mAb therapy that delivers passive immunization against RSV disease.

A CDC report released on May 8, 2025, demonstrated that in 2024–25, RSV hospitalization rates were 45-52% lower in infants younger than 3 months old and 28-43% lower in infants younger than 8 months old compared to the 2018-2020 seasons before product introduction. In the United States, among mothers with an infant younger than eight months, 41.3% reported that their infant received nirsevimab as of March 2024.

RSV Monoclonal Antibody Availability 2025

AstraZeneca and Sanofi co-developed Beyfortus™ (Nirsevimab-alip), a U.S. FDA-approved, single-dose, long-acting mAb designed to protect infants through their first and second RSV seasons. The European Commission granted Beyfortus worldwide approval on November 4, 2022, followed by approvals from the UK, Canada, and the USA. 

Merck's ENFLONSIA™ (Clesrovimab, MK-1654) is an extended half-life monoclonal antibody (mAb) developed as a passive immunization to prevent RSV-associated medically attended lower respiratory infections during the first RSV season. A phase 2/3 clinical trial result published in The New England Journal of Medicine confirmed that clesrovimab mitigates the risk of viral resistance and reduces the risk of viral escape. 

Synagis® (Palivizumab) is a multi-dose injectable RSV antibody that provides one month of protection, requiring five injections to cover a typical RSV season. The U.S. FDA (1998) and Canada, Japan, Israel, the U.K., and India (2023) have approved Synagis to protect at-risk infants against RSV.

Motavizumab is a discontinued investigational RSV mAb. MedImmune filed the original BLA in January 2008.

RSV Monoclonal Antibody Candidates

Shanghai Ark Biopharmaceutical Co., Ltd. announced on November 23, 2023, that it had received IND approval from the National Medical Products Administration in China for its novel antibody, AK0610, which targets RSV. The drug is anticipated to protect infants throughout the entire RSV season. ArkBio licensed the drug's intellectual properties from the Institute of Microbiology, Chinese Academy of Sciences, Beijing Children's Hospital, Capital Medical University, and National Center for Children's Health.

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The peer-review JAMA Network published an Original Investigation focused on the most appropriate monoclonal antibody (mAb) for preventing respiratory syncytial virus (RSV) in children.

This analysis was essential since RSV is a leading cause of respiratory disease in children and the primary cause of hospitalization for viral respiratory infections.

Published on February 17, 2023, this systematic review and network meta-analysis comparing the efficacy and safety of 4 mAbs for preventing RSV infection in children found associations with the improvement of clinically meaningful outcomes and no significant associations with RSV-related adverse effects and mortality.

These findings suggest that motavizumab, nirsevimab, and palivizumab are associated with reduced rates of RSV infections and hospitalizations.

Similar results were observed in the rate of supplemental oxygen use.

While RSV vaccine candidates are completing late-stage clinical studies, mAbs targeting RSV prevention have been U.S. Food and Drug Administration (FDA) for years.

For example, the U.S. CDC CDCHAN-00479 stated on November 4, 2022, that eligible high-risk children should receive the mAbs palivizumab (Synagis) treatment according to AAP guidelines to prevent RSV-associated hospitalizations. 

Recently, the Biologics License Application for nirsevimab (Beyfortus®) was accepted for review by the FDA on January 5, 2023. The FDA's Prescription Drug User Fee Act date for its decision is in the third quarter of 2023.

If approved, nirsevimab would become available in the U.S. for the 2023/2024 RSV season. 

Nirsevimab (MEDI8897) was developed in partnership between AstraZeneca and Sanofi.

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Moderna Inc. today announced one of five influenza vaccine candidates in its portfolio published interim results from its pivotal Phase 3 safety and immunogenicity trial.

mRNA-1010 (P301) is an mRNA-based seasonal influenza (flu) vaccine candidate for adults.

mRNA-1010 encodes for hemagglutinin (HA) glycoproteins of the four influenza strains recommended by the World Health Organization (WHO) to prevent influenza.

Interim results indicate that mRNA-1010 achieved superiority on seroconversion rates for A/H3N2 and A/H1N1 and superiority on geometric mean titer ratios for A/H3N2 and non-inferiority on geometric mean titer ratios for A/H1N1.

Non-inferiority was not met for either endpoint for the influenza B/Victoria- and B/Yamagata-lineage strains.

"Today's results represent an important step forward in developing mRNA-based influenza vaccines to address the substantial burden of disease caused by influenza."

"We are encouraged by the safety and tolerability profile and the strong immunogenicity results against Influenza A viruses which cause the overwhelming majority of flu-related disease in older adults."

"We now look forward to the efficacy results from the ongoing pivotal Phase 3 efficacy study being conducted in parallel," said Stephen Hoge, M.D., Moderna's President, in a press release on February 16, 2023.

"While we did not achieve non-inferiority for the Influenza B strains, which are more frequent in younger populations, we have already updated the vaccine that we believe could improve immune responses against Influenza B and will seek to quickly confirm those improvements in an upcoming clinical study thanks to the agility of our mRNA platform."

The first per-protocol interim analysis of efficacy is now expected to be reviewed by an independent Data and Safety Monitoring Board (DSMB) before the end of the first quarter of 2023.

Based on these results, the DSMB will notify the Company whether the primary efficacy endpoint has been met or whether the study should continue accruing further cases toward the final analysis.

Moderna is advancing a portfolio of five influenza vaccine candidates that include additional HA antigens for broader coverage of circulating influenza A strains (mRNA-1011 and mRNA-1012) and candidates that incorporate both HA and neuraminidase (NA) antigens to target multiple proteins involved in the influenza virus lifecycle to reduce the potential of viral antigenic escape (mRNA-1020 and mRNA-1030).

Moderna is also developing combination vaccine candidates, including vaccine candidates against influenza and SARS-CoV-2, influenza and RSV, and influenza, SARS-CoV-2, and RSV.

The goal of Moderna's combination vaccine candidates is to protect against multiple respiratory pathogens in a single vaccine.

Moderna's unedited press release is available at this link.

Other flu shot news is posted at PrecisionVaccinations.

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The Kaiser Family Foundation (KFF) Covid Vaccine Monitor announced today found 38% of people say their households were affected by this winter’s triple threat of respiratory viruses, with someone getting sick with influenza, COVID-19, or respiratory syncytial virus (RSV).

And 46% of the survey respondents say the news of these three viruses spreading has made them more likely to wear masks or take other precautions to avoid getting sick.

At the same time, 69% of the U.S. public says they are “not too” or “not at all” worried about getting seriously ill from COVID-19, though 31% still say they are worried.

That’s more than people say about the seasonal flu (26%) or RSV (25%).

The flu affected the largest share of households over the past month or so (27%).

With smaller shares saying someone in their homes got sick with COVID-19 (15%) or RSV (10%).

While various flu and COVID-18 vaccines are available in the U.S., RSV vaccine candidates have yet to be approved by the U.S. Food and Drug Administration in 2023.

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January 30, 2023
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Moderna, Inc. today announced that its investigational mRNA vaccine candidate for the respiratory syncytial virus (RSV) mRNA-1345, has been granted Breakthrough Therapy Designation by the U.S. Food and Drug Administration (FDA) for the prevention of RSV-associated lower respiratory tract disease (RSV-LRTD) in adults aged 60 years or older.

Moderna also confirmed it intends to submit a license application to the FDA for regulatory approval in the first half of 2023.

"The FDA's Breakthrough Designation for mRNA-1345 further emphasizes the significant health impact of RSV in older adults and the high unmet need," said Stéphane Bancel, Chief Executive Officer of Moderna, in a press release on January 30, 2023. 

Moderna's mRNA platform has demonstrated two positive Phase 3 infectious disease trial results."

This designation is granted to expedite the development and review of drugs intended to treat a serious condition and when preliminary clinical evidence indicates the drug or vaccine may demonstrate substantial improvement over available therapy on a clinically significant endpoint.

mRNA-1345 was previously granted Fast Track designation by the FDA in August 2021.

RSV can cause severe disease, with an estimated 5.2 million cases and nearly half a million hospitalizations in adults 60 years or older reported across high-income countries in 2019, says the U.S. Centers for Disease Control and Prevention.

Each year in the U.S., approximately 60,000-120,000 older adults are hospitalized, and 6,000-10,000 die due to RSV infection.

As of January 30, 2023, the FDA has not approved any RSV vaccine candidates but authorized RSV antibody treatments.

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mRNA-1345 Respiratory Syncytial Virus (RSV) Vaccine
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Moderna, Inc. announced positive topline data from its ConquerRSV Phase 3 pivotal efficacy trial of mRNA-1345, an mRNA vaccine candidate targeting respiratory syncytial virus (RSV) in older adults.

Following review by an independent Data and Safety Monitoring Board (DSMB), the primary efficacy endpoints have been met, including vaccine efficacy (VE) of 83.7% (95.88% CI: 66.1%, 92.2%; p<0.0001) against RSV-associated lower respiratory tract disease as defined by two or more symptoms.

Based on these results, Moderna stated on January 17, 2023, it intends to submit for regulatory approval for mRNA-1345 in the first half of 2023.

"RSV significantly affects the health of older and high-risk adults, particularly those with comorbidities," commented Abdullah Baqui, a principal investigator for the study sites in Bangladesh and Professor, Department of International Health, Director, International Center for Maternal and Newborn Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, in a related press release.

"This trial will help to understand the role of severe acute respiratory infections in older adult populations and inform the future implementation of vaccines in adults in lower-resource areas."

A concurrent review of available safety data was also conducted by the DSMB.

mRNA-1345 was well tolerated, with no safety concerns identified. To date, most solicited adverse reactions were mild or moderate, and the most commonly reported solicited adverse reactions in the mRNA-1345 group were injection site pain, fatigue, headache, myalgia, and arthralgia.

The overall rate of severe (Grade 3 or greater) solicited systemic adverse reactions was 4.0% for mRNA-1345 and 2.8% for placebo.

The overall rate of Grade 3 or greater solicited local adverse reactions was 3.2% for mRNA-1345 and 1.7% for placebo.

The study is ongoing, and an updated analysis of safety and tolerability will be provided at the time of regulatory submission.

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Aura Air Inc. today announced the findings of an independent study confirming that the company's data-driven air purification devices are highly effective in eliminating the airborne pathogens that contribute to Respiratory Syncytial Virus (RSV).

A recent study by Innovative Bioanalysis Laboratory shows Aura Air's four-stage purification process filters and removes 99.997% of airborne RSV.

According to the U.S. Centers for Disease Control and Prevention, RSV results in approximately 58,000 annual hospitalizations.

Aura Air has partnered with schools, hospitals, and medical associations like the New Jersey Hospital Association (NJHA) to help them combat the spread of RSV, COVID-19, and the flu.

"Hospitals and communities across the country are being hit by an unprecedented surge in patients suffering from RSV, especially very young children," said New Jersey Hospital Association's SVP Michael A. Guerriero in a press release on January 4, 2023.

"Aura Air's advanced air purification and disinfection technology provide a welcome line of defense against these highly contagious viruses."

In addition to RSV, Sheba Medical Center, a leading Israeli medical facility, and Innovative Bioanalysis Laboratory confirmed that Aura Air successfully filters and removes 99.99% of airborne SARS-CoV-2 and 99.98% of Influenza A viruses.

Aura is headquartered in Israel with global offices in the U.S. and India, with distribution in about 87 countries.

Note: As of January 4, 2023, the U.S. FDA has not approved an RSV-preventive vaccine.

Disclosures: This content was sourced from the company and is not paid content.

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