Exercise of Share Options

OPEN ORPHAN PLC

("Open Orphan" or the "Company")

Exercise of Share Options

Open Orphan (AIM: ORPH), a rapidly growing specialist pharmaceutical services clinical research organisation (CRO) and a world leader in vaccine and antiviral testing using human challenge clinical trials, announces that following the exercise of share options by a former hVIVO employee, application has been made to AIM for the admission of 1,048,586 new ordinary shares of 0.1 pence each (the "New Ordinary Shares"). Admission to trading on AIM of the New Ordinary Shares ("Admission"), which will rank pari passu in all respects with the Company's existing shares in issue, is expected to occur on 13 May 2021.

Following Admission, the total number of ordinary shares with voting rights in issue will be 670,450,196 and this figure may be used by shareholders as the denominator for the calculations by which they will determine if they are required to notify their interest in, or a change to their interest in, the Company under the Financial Conduct Authority's Disclosure and Transparency Rules.

Notes to Editors

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

Open Orphan runs challenge studies in London from both its 19-bedroom Whitechapel quarantine clinic, opened in February 2021, and its 24-bedroom QMB clinic which also has a highly specialised virology and immunology laboratory on-site. Open Orphan has a leading portfolio of eight human challenge study models for conditions such as RSV, flu, asthma and COPD. In addition, Open Orphan is also developing the world's first COVID-19 human challenge study model as part of the Human Challenge Programme and has signed a reservation contract with the UK Government for the first three COVID-19 vaccine challenge 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. The Disease in Motion platform has many potential applications across a wide variety of end users including big technology, wearables, pharma and biotech companies. Following COVID-19 there is now a renewed interest and investment in infectious diseases.

Open Orphan's Paris office has been providing biometry, data management and statistics to its many European pharmaceutical clients for over 20 years. For over 15 years, the Company's Netherlands office has been providing drug development consultancy and services, including CMC (chemistry, manufacturing and controls), PK and medical writing, to a broad range of European clients. Both offices are now also fully integrated with the London office and working on challenge study contracts as well as supporting third party trial contracts.