Open Orphan PLC (ORPH.L) Positive results from RSV Human Challenge Study

RSV Human Challenge Study conducted by hVIVO yields positive results

Open Orphan plc (AIM: ORPH), a rapidly growing specialist pharmaceutical services clinical research organisation (CRO) and world leader in vaccine and antiviral testing using human challenge clinical trials , notes the announcement dated 1 September 2021 from Barvarian Nordic A/S (OMX: BAVA), reporting positive results received from a human challenge study testing its respiratory syncytial virus (“RSV”) vaccine candidate, MVA-BN® RSV. hVIVO , a subsidiary of Open Orphan, conducted the Phase 2 double-blinded, placebo controlled trial using its RSV Human Challenge Study Model.

The trial enrolled 61 healthy adult volunteers, 18-50 years of age who were randomised to receive either a single vaccination of MVA-BN RSV or placebo. Following this, volunteers were challenged intranasally with an RSV type A strain 28 days. The study demonstrated a significant reduction in viral load in vaccinated subjects (n=30) versus placebo (n=31), thus meeting the primary endpoint of this pivotal study. At the same time, the vaccinated subjects showed a significant reduction in clinical symptoms typically associated with RSV infections. The MVA-BN RSV vaccine demonstrated a vaccine efficacy of up to 79% in preventing symptomatic RSV infections. No vaccine-related serious adverse events were observed, and the vaccine was well tolerated, consistent with the safety profile previously reported in Phase 1 and Phase 2 clinical studies.

RSV is a contagious virus that affects the respiratory tract of children and at-risk older adults; in severe cases, it can cause pneumonia and other life-threatening breathing difficulties. RSV is a significant public health threat and is one of the leading causes of hospitalisation to at-risk older adults. Among the elderly (aged 65+), RSV causes as many hospitalisations and deaths as influenza (source: CDC). In the current climate, RSV may also lower immunity and increase the risk of developing COVID-19, and where these infections occur together, it can worsen the severity of COVID-19 illness. There is currently no vaccine on the market for RSV.

hVIVO has two decades of experience and expertise in safely conducting challenge studies across a range of respiratory and infectious disease viruses, including various strains of influenza, RSV, HRV, asthma and malaria, etc.

Cathal Friel, Executive Chairman, said: “We are delighted to see the positive results emerge from this RSV Human Challenge Study with Bavarian Nordic for its RSV vaccine candidate, which was run by hVIVO. This Study illustrates the Company’s diverse offering across the infectious disease market.

“We are the only company in the world that is currently equipped to run RSV challenge studies, which forms part of our wider portfolio of respiratory and infectious disease challenge trials. With the global infectious disease market expected to reach a value of $250bn by 2025, we are already seeing a huge increase in interest across the entire pharmaceutical and biotech space in these previously underserved infectious disease areas. We look forward to offering our industry leading services to help novel therapeutics and vaccines progress through clinical development.”

Interested in becoming a volunteer?

hVIVO recruits many of its volunteers for its challenge study clinical trials through its dedicated volunteer recruitment website, By volunteering to take part in one of our studies in a safe, controlled, clinical environment under expertly supervised conditions you are playing your part to further medical research and help increase the understanding of respiratory illnesses.

Individuals interested in taking part in COVID-19 human challenge study research can learn more at

For further information please contact:

Cathal Friel, Executive Chairman

Open Orphan plc

+353 (0) 1 644 0007

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