hVIVO plc

("hVIVO" or the "Company")

Omicron human challenge model update

hVIVO plc (AIM & Euronext: HVO), (formerly Open Orphan plc) 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 its Omicron human challenge agent has been successfully manufactured.

Subject to the successful completion of the characterisation study and receipt of relevant regulatory approvals, this has expanded the Company's unique portfolio to 11 human challenge models to test a broad range of infectious and respiratory disease products. hVIVO actively offers Omicron human challenge trials as part of its service offering and is currently in discussions with a number of existing and potential customers.

As announced on 30 June 2022, the model was developed with Vaxart Inc. ("Vaxart"), (NASDAQ: VXRT) with the intent to conduct a subsequent Omicron human challenge study to test the efficacy of Vaxart's oral vaccine candidate. The Company notes the announcement from Vaxart and its decision to postpone further clinical trials in its COVID-19 programme, including the challenge study, as they focus upon the development of an oral pan-betacoronavirus vaccine, which may provide improved protection against SARS-CoV-2 as the virus continues to mutate and protection against other types of betacoronaviruses.

The Vaxart challenge study was not included in the Company's order book and its postponement will have no impact on hVIVO's 2023 financial guidance. As at 31 December 2022 the Company's orderbook was £76m, with over 95% of forecasted revenue for 2023 contracted.

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Notes to Editors

About hVIVO

hVIVO plc (ticker: HVO) (formerly Open Orphan plc) is a rapidly growing specialist contract research organisation (CRO) and the world leader in testing infectious and respiratory disease vaccines and therapeutics using human challenge clinical trials. The Group provides end-to-end early clinical development services to its large, established and growing repeat client base, which includes four of the top 10 largest global biopharma companies.

The Group's fast-growing services business includes a unique portfolio of 11 human challenge models, with a number of new models under development, to test a broad range of infectious and respiratory disease products. The Company has world class challenge agent manufacturing, specialist drug development and clinical consultancy services via its Venn Life Sciences brand, and a lab offering via its hLAB brand, which includes virology, immunology biomarker and molecular testing. The Group offers additional clinical field trial services such as patient recruitment and clinical trial site services.

hVIVO 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 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.