Open Orphan plc

("Open Orphan" or the "Company")

hVIVO to develop the world's first Omicron human challenge model

 Vaxart becomes the first client of the programme to test its oral COVID-19 vaccine candidate

Open Orphan plc (AIM: ORPH), a rapidly growing specialist contract research organisation (CRO) and world leader in testing infectious and respiratory disease products using human challenge clinical trials, announces that hVIVO, a subsidiary of Open Orphan, is developing the world's first Omicron human challenge model. hVIVO has signed an agreement with Vaxart Inc. ("Vaxart"), (NASDAQ: VXRT) to develop the model with the intent to conduct a subsequent Omicron human challenge study in 2023 to test the efficacy of Vaxart's oral vaccine candidate, VXA-CoV2-1.

To develop the model, hVIVO will manufacture a new SARS-CoV-2 (COVID-19) challenge agent based on the Omicron variant. The Good Manufacturing Practice ("GMP") compliant virus manufacturing activities will commence immediately and are expected to complete by Q4 2022. Following manufacture of the challenge agent, the Company intends to conduct a characterisation study. Subject to the successful completion of the characterisation study and receipt of relevant regulatory approvals, hVIVO expects to conduct Omicron human challenge studies in 2023.

The characterisation study will establish a dose of the Omicron challenge agent that will cause a safe and reliable infection in healthy volunteers. The study will enrol healthy male and female volunteers who have previously been vaccinated against or infected with SARS-CoV-2, with no known risk factors for severe COVID-19 and low levels of serum neutralising antibodies (and therefore still likely to become infected following inoculation).

hVIVO has two decades of experience and expertise in challenge agent manufacture and clinical characterisation across a range of respiratory viruses including various strains of influenza, respiratory syncytial virus (RSV), human rhinovirus (hRV - common cold virus), as well as the initial circulating SARS-CoV-2 virus and variants which have since emerged. hVIVO leads the Challenge Agent Manufacture Consortium, which has developed international standards that pertain to challenge agent manufacture and storage, to ensure safety, quality and consistency.

Yamin Khan, Chief Executive Officer of Open Orphan, said: "With our leading end-to-end human challenge expertise, we are delighted to be developing the world's first Omicron human challenge model and to welcome Vaxart as the first client of this programme.

"hVIVO's fight against the pandemic continues with the development of this new challenge agent. The benefits to Vaxart are immense, and we have already been contacted by a number of biopharma companies looking to test the efficacy of their products using this challenge virus. I have no doubt that the successful completion of the world's first COVID-19 characterisation, which was published in Nature Medicine earlier this year, has given our customers the confidence to move forward with the less severe yet more infective Omicron challenge model."

Dr. James Cummings, Chief Medical Officer of Vaxart, said: "A human challenge study of our oral tablet COVID-19 vaccine candidate against the Omicron variant of SARS-CoV-2 is the most rapid and direct way to assess the efficacy of this candidate against a highly prevalent viral strain.

"hVIVO has pioneered COVID-19 characterization and the Omicron human challenge model, and the use of this model in our planned Phase II human challenge trial will rapidly generate robust, controlled data on the ability of our COVID-19 vaccine candidate to prevent infection and the development of symptomatic disease, as well as its effect on viral shedding, which plays a critical role in the spread of infection from one person to another. The results of this study will inform the next steps in the development of our COVID-19 vaccine candidate, which has the potential to transform personal and public health approaches to controlling the global pandemic."

Dr Andrew Catchpole, Chief Scientific Officer of hVIVO, said: "The team and I at hVIVO are excited to begin work to manufacture an Omicron challenge agent, the follow-on characterisation, and future human challenge trials. We have unparalleled expertise in SARS-CoV-2 challenge agent manufacturing, having completed work on both the original Wuhan strain and the subsequent Delta variant, in addition to our prior experience in successfully conducting the world's first COVID-19 characterisation study, and our decades of experience in conducting human challenge trials. We are delighted to be working with Vaxart on this programme and look forward to the opportunity to subsequently test the efficacy of their exciting novel vaccine."

Interested in becoming a volunteer?

hVIVO recruits many of its volunteers for its challenge study clinical trials through its dedicated volunteer recruitment website, www.flucamp.com. 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.

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Notes to Editors

Open Orphan plc

Open Orphan plc (London and Euronext: ORPH) is a rapidly growing contract research company that is a world leader in testing infectious and respiratory disease products using human challenge clinical trials. The Company provides services to Big Pharma, biotech, and government/public health organisations.

The Company has a leading portfolio of human challenge study models for infectious and respiratory diseases, including the recently established COVID-19 model, and is developing a number of new models, such as Malaria, to address the dramatic growth of the global infectious disease market. The Paris and Breda offices have over 25 years of experience providing drug development services such as biometry, data management, statistics CMC, PK and medical writing to third party clients as well as supporting the London-based challenge studies.

Open Orphan runs challenge studies in London from its Whitechapel quarantine clinic, its state-of-the-art QMB clinic with its highly specialised on-site virology and immunology laboratory, and its newly opened clinic in Plumbers Row. To recruit volunteers / patients for its studies, the Company leverages its unique clinical trial recruitment capacity via its FluCamp volunteer screening facilities in London and Manchester. The newly opened facilities have expanded the scope of the business to enable the offering of Phase I and Phase II vaccine field trials, PK studies, bridging studies, and patient trials as part of large international multi-centre studies.

Building upon its many years of challenge studies and virology research, the Company is developing an in-depth database of infectious disease progression data. Based on the Company's Disease in Motion® platform, this unique dataset includes clinical, immunological, virological, and digital (wearable) biomarkers.

About Vaxart

Vaxart is a clinical-stage biotechnology company developing a range of oral recombinant vaccines based on its proprietary delivery platform. Vaxart vaccines are designed to be administered using tablets that can be stored and shipped without refrigeration and eliminate the risk of needle-stick injury. Vaxart believes that its proprietary tablet vaccine delivery platform is suitable to deliver recombinant vaccines, positioning the company to develop oral versions of currently marketed vaccines and to design recombinant vaccines for new indications. Vaxart's development programs currently include tablet vaccines designed to protect against coronavirus, norovirus, seasonal influenza, and respiratory syncytial virus (RSV), as well as a therapeutic vaccine for human papillomavirus (HPV), Vaxart's first immune-oncology indication. Vaxart has filed broad domestic and international patent applications covering its proprietary technology and creations for oral vaccination using adenovirus and TLR3 agonists.

About Human Challenge Trials

During human challenge trials, healthy volunteers are administered a pathogenic or virulent strain of a challenge agent (which can be a virus, bacteria, or a parasite), in a safe and controlled quarantine setting to assess the efficacy of vaccines or treatments.

About Omicron

The Omicron variant of SARS-CoV-2, similarly to previous variants, is comprised of several lineages and sublineages. Since its discovery, it has spread more rapidly than earlier variants of the virus yet is generally considered to cause less severe disease than infection with prior variants, such as Delta.