Respiratory Syncytial Virus (RSV) Vaccines For 2022
The development of respiratory syncytial virus (RSV) vaccines has been identified as a priority for the World Health Organization (WHO) Initiative for Vaccine Research. And various pharmaceutical companies are conducting late-stage clinical trials. RSV vaccine development began in the 1960s.
As of September 26, 2022, the U.S. FDA had not Approved any RSV vaccine. And various research studies are actively recruiting children and adults to join RSV clinical trials.
The peer-review journal The Lancet published on August 8, 2022 - RSV prevention within reach: an overview of vaccines and monoclonal antibodies in clinical development highlighting different target populations, antigens, and trial results. And the Journal of Infectious Diseases published: Impact of RSV on Child, Caregiver, and Family Quality of Life in the USA: Systematic Literature Review and Analysis on August 15, 2022.
The U.S. CDC Respiratory Syncytial Virus Work Group presented on June 23, 2022 - RSV virion and vaccine products by Natalie Thornburg; Epidemiology of RSV in children by Dr. M McMorrow; Epidemiology of RSV in adults by Dr. F Havers; Safety and efficacy of Nirsevimab in infants by Dr. C Felter. In addition, on January 12, 2022, Sarah S. Long, MD, Chair, Maternal/Pediatric RSV Work Group, presented 'Introduction to ACIP's Maternal/Pediatric RSV Work Group' during the U.S. CDC meeting.
RSV Vaccine Price
As of September 2022, the U.S. CDC's Vaccine Price List did not disclose RSV vaccine prices. However, the global RSV Therapeutics Market Size is estimated to reach about $836 million by 2028, exhibiting a CAGR of 5.76%. Additional RSV vaccine price and discount information are posted at InstantRx™.
RSV Vaccine Clinical Trials
Numerous RSV clinical trials seek participants for research studies listed on this sponsored webpage.
RSV Vaccine Candidates
mRNA-1345 is a vaccine against RSV developed by Moderna, Inc., encoding for a prefusion F glycoprotein, eliciting a superior neutralizing antibody response compared to the postfusion state.
GSK's RSV OA investigational single-dose RSV vaccine candidate is currently conducting a phase 3 study in adults aged 60 and above. It contains a recombinant subunit pre-fusion RSV antigen (RSVPreF3) combined with GSK's proprietary AS01 adjuvant.
Janssen RSV Vaccine candidate efficacy and immunogenicity data from the Phase 2b CYPRESS study demonstrated 80% vaccine efficacy in adults aged 65 and older. In addition, a Phase 3 Study of an Adenovirus Serotype 26 Pre-fusion Conformation-stabilized F Protein (Ad26. RSV. preF) Based RSV Vaccine in the Prevention of Lower Respiratory Tract Disease in Adults Aged 60 Years and Older.
MVA-BN RSV, Bavarian Nordic's vaccine candidate, incorporates five different RSV antigens to stimulate a broad immune response against both RSV subtypes (A and B), thus mimicking the immune response observed following a natural reaction to an RSV infection.
Meissa Vaccines MV-012-968 is an investigational, live attenuated vaccine protecting against respiratory syncytial virus infection.
ResVax is a vaccine candidate from Novavax composed of recombinant RSV F nanoparticles adsorbed to aluminum phosphate. The F protein is essential to RSV infectivity and is the target of palivizumab.
DS-Cav1 was developed by VRC, NIAID, and is composed of the RSV fusion glycoprotein ectodomain assembled as a trimer stabilized in its prefusion native conformation with a foldon trimerization domain at the C-terminus and four internal mutations designated DS-Cav1 (4.1DHFR_RSVAF).
IVX-121, an RSV vaccine candidate, incorporates a stabilized prefusion F antigen licensed from NIAID/NIH (DS-CAV1). VLP technology further enhances the magnitude, quality, and durability of the response to the prefusion RSV F., The enhanced response to VLP-based prefusion F could be particularly important in older adult populations
RSVpreF vaccine candidate from Pfizer Inc. is currently in phase 3 clinical study and recently received Breakthrough Therapy Designation(s) from the U.S. FDA for infants and seniors.
Ad26.RSV preF vaccine is a protein-based RSV vaccine candidate tested on adults produced by Pfizer, Inc.
EDP-938, Enanta's lead N-protein inhibitor, is being developed to treat RSV infection and was granted Fast Track Designation by the U.S. FDA.
BLB-201 is an intranasal vaccine for the prevention of RSV infection from Blue Lake Biotechnology, Inc. BLB-201 is based on an attenuated strain of canine parainfluenza virus and expresses the RSV-F protein and is conducting a phase 1 study of CPI-RSV-F Vaccine (BLB-201). The FDA granted Fast Track status on May 24, 2022.
Codagenix Inc. CodaVaxTM-RSV is an intranasal, live-attenuated vaccine candidate for preventing RSV infection in healthy infants and toddlers.
Icosavax Inc. plans to submit an IND for IVX-A12 to the U.S. FDA and initiate a Phase 1 clinical trial in 2H 2022. This study will examine the safety and immunogenicity of bivalent (RSV/hMPV) formulations, incorporating a single RSV dosage level and multiple hMPV dosage levels.
Sanofi and AstraZeneca Beyfortus® (Nirsevimab) is an investigational, single-dose, long-acting antibody designed to protect all infants through their first RSV season. Nirsevimab is the first potential immunization to show protection against RSV in the general infant population in a Phase III trial.
AstraZeneca's Synagis (Palivizumab) anti-RSV antibody is limited to high-risk infants and provides one-month protection, requiring five injections to cover an RSV season. The U.S. FDA (1998), Canada, Japan, Israel, and the UK have approved Palivizumab (Synagis) to protect at-risk patients (premature babies, infants) against RSV. The recommended dose of palivizumab is 15mg/kg of body weight once a month has been shown to decrease hospitalizations.
RSV Vaccine News
September 16, 2022 - The European Medicines Agency’s Committee for Medicinal Products for Human Use adopted a positive opinion for Beyfortus® (nirsevimab) for the prevention of RSV lower respiratory tract disease in newborns and infants during their first RSV season.
September 2, 2022 - The Lancet published an analysis - Quantifying the RSV immunity debt following COVID-19: a public health matter.
August 25, 2022 - Pfizer Inc. announced positive top-line data from the Phase 3 clinical trial (RENOIR). Pfizer's RSVpreF efficacy of 85.7% was observed in participants with more severe disease primary endpoint of lower respiratory tract illness defined by analysis of three or more RSV-associated symptoms.
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 study. More than 20,000 infants across 3 countries (U.K., France, and Germany) will be enrolled from August 2022 to March 2023.
August 8, 2022 - The Lancet published - the RSV prevention landscape - If all the ongoing phase 3 trials generate positive results, relative efficacy and safety trial data, delivery strategies, and costs might determine vaccine uptake for different maternal and older adult candidates. Despite the approval of next-generation antibodies, palivizumab might remain on the market until there is global market access to extended half-life mAbs and because mAb supply might not meet global demand.
July 21, 2022 - Science.org published: AI churns out possible medicines and vaccines. New AI software that can "paint" structures for proteins that don't yet exist in nature.
July 21, 2022 - Blue Lake Biotechnology, Inc. announced the enrollment of the first participant in the Phase 1 clinical trial of their intranasal BLB-201 vaccine for RSV in Charleston, South Carolina.
July 7, 2022 - The UKHSA reported RSV positivity remained stable at 4.4% overall and decreased slightly to 13.0% in under 5-year-olds in week #26.
June 28, 2022 - Icosavax, Inc. announced positive topline interim results from its Phase 1/1b clinical trial of IVX-121, a VLP displaying a prefusion stabilized RSV F antigen, in young and older adults.
June 23, 2022 - The NEJM published an ORIGINAL ARTICLE: Vaccine Efficacy in Adults in a Respiratory Syncytial Virus Challenge Study. The RSVpreF vaccine was effective against symptomatic RSV infection and viral shedding in a phase 2 study. In addition, no evident safety concerns were identified.
June 10, 2022 - GSK plc announced its RSV OA vaccine candidate showed statistically significant and clinically meaningful efficacy in adults aged 60 years and above in a phase 3 study. The magnitude of effect observed was consistent across RSV A and B strains, key secondary endpoints, and those aged 70 years and above.
June 8, 2022 - Associate Professor of Biomolecular Engineering at the Baskin School of Engineering Rebecca DuBois has been awarded the prestigious and highly competitive National Institutes of Health Research Project Grant of $3.8 million.
June 1, 2022 - Codagenix Inc. announced that the U.S. FDA approved the Investigational New Drug application for CodaVaxTM-RSV.
May 24, 2022 - A study published by the journal Nature revealed: that in late 2020, unprecedented widespread RSV outbreaks occurred, beginning in spring, and extending into summer, across two widely separated regions of the Australian continent, New South Wales (NSW) and Australian Capital Territory (ACT). Through genomic sequencing, we reveal a major reduction in RSV genetic diversity following COVID-19 emergence with two genetically distinct RSV-A clades circulating cryptically, likely localized for several months before an epidemic surge in cases. However, the NSW/ACT clade spread to the neighboring state of Victoria and caused extensive outbreaks and hospitalizations in early 2021. These findings highlight the need for continued surveillance and sequencing of RSV and other respiratory viruses during and after the COVID-19 pandemic, as mitigation measures may disrupt seasonal patterns, causing more extensive or severe outbreaks.
May 24, 2022 - Blue Lake Biotechnology, Inc. announced that the U.S. FDA was granted Fast Track designation for BLB-201, an intranasal vaccine for the prevention of RSV-associated disease in adults over 60 and children under two years of age.
May 19, 2022 - The Lancet published systematic analysis of global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in children younger than five years in 2019.
May 16, 2022 - The U.S. FDA authorized the Labcorp Seasonal Respiratory Virus RT-PCR DTC Test for use without a prescription that can identify and differentiate multiple respiratory viruses simultaneously, detecting influenza A and B, respiratory syncytial virus, commonly known as RSV, along with SARS-CoV-2.
May 11, 2022 - AstraZeneca announced findings contribute to the growing body of evidence that nirsevimab has the potential to protect all infants entering their first RSV season with a single dose.
May 2, 2022 - The WHO Influenza Update N° 418 confirmed RSV activity remained low in the U.S., Brazil, and Canada compared with pre-COVID-19 pandemic seasons.
April 28, 2022 - The NEJM published an Original Article (Phase 2b study): Prefusion F Protein-Based Respiratory Syncytial Virus Immunization in Pregnancy. CONCLUSIONS: RSVpreF vaccine-elicited neutralizing antibody responses with efficient transplacental transfer and without evident safety concerns.
April 20, 2022 - Bavarian Nordic A/S announced the dosing of the first subject in the Phase 3 VANIR clinical trial of its MVA-BN® RSV vaccine candidate in older adults.
April 4, 2022 - The WHO published Influenza Update N° 416 - In North America, RSV activity further decreased in the U.S. and Canada. And in Europe, overall, very little RSV activity was observed.
April 3, 2022 - The Israeli Health Ministry has authorized the expanded vaccination of premature babies against RSV with Palivizumab (Synagis).
March 28, 2022 - CyanVac LLC and its subsidiary, Blue Lake Biotechnology, Inc., announced that the U.S. FDA had cleared the investigational new drug application for BLB-201, an intranasal vaccine for the prevention of RSV infection.
March 25, 2022 - The Lancet published a correspondence: SARS-CoV-2 co-infection with influenza viruses, respiratory syncytial virus, or adenoviruses. Viral co-infection was detected in 583 (8·4%) patients: 227 had influenza viruses, 220 had the respiratory syncytial virus, and 136 had adenoviruses.
March 22, 2022 - Modernatx Inc. is launching a respiratory combination vaccine program to target three of the most significant viruses causing respiratory disease in older adults. The new combination respiratory vaccine candidate (mRNA-1230) is envisioned as an annual booster targeting the SARS-CoV-2, influenza, and RSV.
March 21, 2022 - The WHO's Influenza Update N° 415 stated, 'In North America, respiratory syncytial virus activity further decreased in the U.S. and Canada.
March 21, 2022 - Bavarian Nordic A/S announced a development and commercialization agreement with Nuance Pharma of MVA-BN® RSV in China, Hong Kong, Macau, Taiwan, South Korea, and certain Southeast Asian countries.
March 14, 2022 - The journal PNAS published research on the prevention of antimicrobial prescribing among infants following maternal vaccination against the respiratory syncytial virus (RSV). In a double-blind, randomized, placebo-controlled trial, administering an RSV vaccine candidate to pregnant mothers reduced antimicrobial prescribing among their infants by 12.9% over the first three months of life.
March 10, 2022 - The Journal of Virology published - Structure-Based Design and Antigenic Validation of Respiratory Syncytial Virus G Immunogens. These studies show for the first time that an engineered RSV G protein with increased immunogenicity and safety retains conformational epitopes to high-affinity protective antibodies, supporting its further development as an RSV vaccine immunogen.
March 3, 2022 - An Original Article - The Nirsevimab for Prevention of RSV in Healthy Late-Preterm and Term Infants - published by The NEJM; 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. The phase 3 study was funded by MedImmune/AstraZeneca and Sanofi.
March 2, 2022 - Pfizer Inc. announced that its RSV vaccine candidate RSVpreF received Breakthrough Therapy Designation from the U.S. FDA to prevent RSV-associated lower respiratory tract illness in infants from birth up to six months of age by active immunization of pregnant women.
February 28, 2022 - The JAMA Network published an Original Investigation: Mortality Associated With Influenza and Respiratory Syncytial Virus in the US, 1999-2018. This study suggests that RSV poses a greater risk than influenza to infants, while both are associated with substantial mortality among elderly individuals.
February 28, 2022 - London-based GSK announced that further to the voluntary pause shared on February 18, the Company has decided to stop enrolment and vaccination in trials evaluating its potential RSV maternal vaccine candidate in pregnant women (NCT04605159, NCT04980391, NCT05229068).
February 27, 2022 - The NEJM published an Original Article: Azithromycin to Prevent Recurrent Wheeze Following Severe Respiratory Syncytial Virus Bronchiolitis. CONCLUSIONS: Azithromycin therapy for 14 days during acute severe RSV bronchiolitis did not reduce recurrent wheezing over the following 2 to 4 years.
February 23, 2022 - A research article: Early initiation of the respiratory syncytial virus season in 2021-2022, Greece - 'Awareness is needed to diagnose even the out-of-season RSV infections, while molecular epidemiology plays a key role in monitoring the efficacy of currently available therapeutics and for those under development.'
February 22, 2022 - Moderna, Inc. announced that the Data and Safety Monitoring Board for the RSV program had endorsed the start of the Phase 3 portion of the pivotal ConquerRSV clinical study of mRNA-1345 in adults 60 years and older.
February 18, 2022 - GlaxoSmithKline plc announced that it has voluntarily paused enrollment and vaccination in the GRACE phase III trial, evaluating its potential RSV maternal vaccine candidate and two other trials investigating this candidate in pregnant women (NCT04980391, NCT05229068).
February 17, 2022 - The European Medicines Agency confirmed it accepted the Marketing Authorization Application for nirsevimab under an accelerated assessment procedure.
February 17, 2022 - The peer-reviewed journal NEJM published Original Research: EDP-938, a Respiratory Syncytial Virus Inhibitor, in a Human Virus Challenge study. All EDP-938 regimens were superior to placebo concerning lowering the viral load, total symptom scores, and mucus weight without apparent safety concerns.
February 16, 2022 - The peer-reviewed journal Infectious Disease published an Accepted Manuscript: Morbidity of Respiratory Syncytial Virus-infections: RSV compared with SARS-CoV-2 infections in children aged 0 – 4 years in Cologne, Germany. Findings: RSV infections required greater hospital resource utilization than SARS-CoV-2 infections.
February 14, 2022 - Copenhagen-based Bavarian Nordic A/S announced its RSV vaccine candidate MVA-BN RSV was granted Breakthrough Therapy Designation by the U.S. FDA for active immunization to prevent lower respiratory tract disease caused by RSV in adults aged 60 years or older.
January 27, 2022 - The National Foundation for Infectious Diseases issued a Call to Action today urging stronger public health focus and increased awareness of RSV in the U.S. The report, Call to Action: Reducing the Burden of RSV across the Lifespan, addresses the underappreciated impact of RSV and outlines key strategic priorities to drive progress in RSV surveillance, diagnosis, prevention, and treatment.
December 29, 2021 - The JAMA Network published: RSV Vaccines, Finally Within Reach, Could Prevent Tens of Thousands of Yearly Deaths.
December 16, 2021 - The JAMA Network published an Orginal Investigation - This simulation modeling study found that virus introduction from external sources was associated with the spring and summer epidemics in 2021. These findings suggest that pediatric departments should be alert to large RSV outbreaks in the coming seasons, the intensity of which could depend on the size of the spring and summer epidemic in that location.
December 7, 2021 - The Janssen Pharmaceutical Inc. announced additional vaccine efficacy and safety data from its Phase 2b CYPRESS study of its respiratory syncytial virus adult vaccine candidate. Results show that the vaccine candidate was highly effective in protecting against three clinical definitions of lower respiratory tract disease caused by RSV, demonstrating vaccine efficacy of 70 to 80% in adults aged 65 and older.
December 6, 2021 - Bavarian Nordic A/S announced its commitment to initiate a Phase 3 clinical trial of its RSV vaccine candidate, MVA-BN® RSV.
December 3, 2021 - MedpageToday published Year in Review: Respiratory Syncytial Virus.
November 18, 2021 - Moderna, Inc. announced the first participant had been dosed in the ConquerRSV Phase 2/3 study of mRNA-1345, an RSV vaccine candidate.
October 20, 2021 - Science Translational Medicine published: Fatal enhanced respiratory syncytial virus disease in toddlers. This article characterizes the clinical, immunopathological, and transcriptional signature of fatal human ERD, outlining the evidence for safety evaluation of RSV vaccines and a framework for understanding disease enhancement for pathogens in general.
October 2, 2021 - The Janssen Pharmaceutical Companies of Johnson & Johnson announced that its investigational RSV vaccine candidate was highly effective in protecting against lower respiratory tract disease caused by RSV, demonstrating a vaccine efficacy of 80% (CI, 52.2-92.9%) in adults aged 65 and older.
September 29, 2021 - The Janssen Pharmaceutical Companies of Johnson & Johnson today announced the initiation of its Phase 3 EVERGREEN study that will evaluate the efficacy, safety, and immunogenicity of Janssen's investigational adult vaccine against lower respiratory tract disease caused by a respiratory syncytial virus, when compared with placebo in approximately 23,000 adults aged 60 years and older throughout North America and a selection of countries across Europe, Asia and the Southern Hemisphere. In September 2019, the U.S. FDA granted Breakthrough Therapy Designation for Janssen's investigational RSV adult vaccine to prevent LRTD caused by RSV in adults aged 60 years or older.
September 16, 2021 - the U.K.'s Public Health England published: Respiratory syncytial virus (RSV) is an enveloped RNA virus, in the same family as the human parainfluenza viruses and mumps and measles viruses. RSV is one of the common viruses that cause coughs and colds in winter.
September 9, 2021 - Seattle-based Icosavax, Inc. announced the initiation of a Phase 1/1b clinical trial of IVX-121, a VLP displaying a Respiratory Syncytial Virus stabilized pre-fusion F antigen in healthy adults and older adults.
September 9, 2021 - Public Health England reported Respiratory syncytial virus positivity decreased slightly to 12.6% in week #35, with the highest positivity in the under 5-year olds.
September 2, 2021 - Pfizer Inc. announced the initiation of RENOIR (RSV vaccine Efficacy study iNOlder adults Immunized against RSV disease), a Phase 3 clinical trial evaluating the efficacy, immunogenicity, and safety of a single dose of its respiratory syncytial virus bivalent prefusion F subunit investigational vaccine candidate (RSVpreF) in adults ages 60 years or older.
September 1, 2021 - Bavarian Nordic A/S announced results from a human challenge phase 2 double-blinded, placebo-controlled trial enrolled healthy adult volunteers, 18-50 years of age, who were randomized to receive a single vaccination of MVA-BN RSV or placebo. Volunteers were challenged intranasally with an RSV type A strain 28 days after vaccination. The study demonstrated a significant reduction in viral load in vaccinated subjects (n=30) versus placebo (n=31).
August 22, 2021 - Public Health England published new Guidance: Respiratory syncytial virus (RSV): symptoms, transmission, prevention, treatment. Palivizumab, a monoclonal antibody therapy, is licensed in the U.K. to prevent serious lower respiratory tract infections caused by RSV in infants at high risk of infection.
August 19, 2021 - Pubic Health England published report #33. Out of the 107,928 respiratory specimens reported through the Respiratory DataMart System (based on data received from 14 out of 16 laboratories), 2351 samples were positive for SARS-CoV-2 with an overall positivity of 2.0%. The highest positivity was noted in the 5 to 14-year olds at 4.3% in week 32. The overall influenza positivity remained very low at 0.0% in week 32, with none of the 2,572 samples testing positive for influenza. Respiratory syncytial virus (RSV) positivity decreased, from 15.2% in week 31 to 13.8% in week 32, with the highest positivity noted in the under 5-year olds at 28.0%.
August 16, 2021 - In Mali, a long-acting monoclonal antibody is likely to be cost-effective from both the government and donor perspectives at $3 per dose.
August 3, 2021 - Moderna, Inc. announced that the U.S. FDA had granted Fast Track designation for the mRNA-1345 RSV vaccine candidate.
July 28, 2021 - During Pfizer's investor call on July 28, CSO Mikael Dolsten reported that the company's protein-based RSV vaccine candidate Ad26.RSV preF vaccine was 100% effective in a human challenge trial at preventing mild-to-moderate infection (meaning any infections were asymptomatic).
July 23, 2021 - The CDC reported changes in influenza and other respiratory viruses, including RSV. During January 4–April 4, 2020, the weekly percentage of positive RSV results decreased from 15.3% to 1.4%, then remained at historically low levels (<1.0% per week) for the following year. The weekly percentage of positive RSV results exceeded 3.0% during the previous four years, beginning in October, with peaks ranging from 12.5% to 16.7% in late December. From April 17–May 22, 2021, the weekly percentage of positive results increased from 1.1% to 2.8%. These historic low activity rates are partly due to the COVID-19 pandemic and subsequent implementation of nonpharmaceutical interventions (e.g., cessation of global travel, mask use, physical distancing, and staying home).
July 20, 2021 - The UK NHS reported during week #28, Respiratory Syncytial Virus positivity increased from 6.8% to 8.9%.
June 11, 2021 - The American Hospital Association reported that the CDC alerted clinicians to an increase in Respiratory Syncytial Virus since late March in certain Southern states. The common respiratory virus usually causes mild cold-like symptoms but can be severe, especially for infants and older adults.
June 10, 2021 - The U.S. CDC issued a health advisory to notify clinicians and caregivers about increased interseasonal respiratory syncytial virus (RSV) activity across parts of the Southern United States. In addition, due to this increased activity, CDC encourages broader testing for RSV among patients presenting with acute respiratory illness who test negative for SARS-CoV-2.
July 30, 2020 - A study published by the NEJM found that RSV F protein nanoparticle vaccination in pregnant women did not meet the prespecified success criterion for efficacy against RSV-associated, medically significant lower respiratory tract infection in infants up to date 90 days of life.
February 16, 2021 - GlaxoSmithKline plc announced that patient dosing has begun in Phase III clinical program investigating the immunogenicity, safety, reactogenicity, and persistence of its RSV candidate vaccine for older adults (GSK3844766A).
December 15, 2020 - GeneFirst Gets CE-IVD Mark for Coronavirus, Flu, RSV Combo Test Kit. The test kit, which provides results in under two hours, is PCR system-agnostic and is suitable for use with a range of instruments, including Roche's LightCycler, and Thermo Fisher Scientific's Applied Biosystems 7500, according to a GeneFirst spokesperson.
November 21, 2020 - 'Good progress is being made in RSV prevention research. DURING A VIRTUAL PRESENTATION, Mary T. Caserta, M.D., a pediatrics professor at the University of Rochester Medical Center, updated several RSV investigational products and vaccines in development for infants and pregnant mothers.
November 18, 2020 - According to the Centers for Disease Control and Prevention, virtually all children get an RSV infection at two years old. RSV will often cause a mild, cold-like illness, but it can also cause severe bronchiolitis and pneumonia.
Ark Biopharmaceutical announced the successful results of the multicenter Phase 3 AirFLO study with ziresovir, a novel, oral, small-molecule RSV fusion protein inhibitor, in infants hospitalized with RSV. Ziresovir demonstrated a rapid onset of clinical effects, showing a 30% additional S&S score reduction compared with placebo (p=0.002) after two days of treatment.