HMPV challenge model update

• Study exhibited strong infectivity rate and induced symptomatic disease in healthy volunteers
• Now marketing for hMPV challenge trials to support the development of hMPV vaccines and antivirals
• Dr Andrew Catchpole to present data from the study at the 13th International RSV Symposium in Brazil

hVIVO plc (AIM: HVO), a fast-growing specialist contract research organisation (CRO) and world leader in testing infectious and respiratory disease products using human challenge clinical trials, announces that it has successfully completed a pilot characterisation study for its human metapneumovirus (hMPV) strain A2 challenge agent, demonstrating proof-of-concept for a future hVIVO hMPV challenge model to test new vaccines and antivirals.

The pilot study, which took place at the Company's state-of-the-art quarantine facility in Canary Wharf, produced a safe, measurable and reproducible disease in healthy volunteers with strong rates of infection and symptomatic disease. This study confirms that the Company has a viable hMPV human challenge model which can be used in future human challenge trials to support the development of hMPV vaccines and antivirals to meet this unmet medical need. The Company is now marketing its hMPV challenge model and will look to complete the remainder of the characterisation study with a partner in advance of completing future human challenge trials.

Dr Andrew Catchpole, Chief Scientific Officer at hVIVO, will present data from the pilot study at a presentation titled 'Disease characteristics and immunological profiles obtained from pilot study in a newly developed hMPV human challenge model' at the 13th International RSV Symposium on 12-15 March 2025 in Iguazu, Brazil.

Dr Andrew Catchpole, Chief Scientific Officer of hVIVO plc, said: "The pilot hMPV characterisation study in healthy volunteers was designed to test the feasibility of this new model and has been very successful, producing good infectivity rates and clear disease symptoms. Like the hVIVO RSV models, I am confident our hMPV model can play a crucial role in speeding up the development of a first vaccine or antiviral for this global pathogen, which is currently causing particular concern in China1 where a surge in cases has been recorded."

1 https://www.ecdc.europa.eu/en/news-events/increase-respiratory-infections-china

About hMPV

hMPV is a common virus that causes an upper respiratory infection, similar to the common cold. Symptoms include cough, fever, nasal congestion, and shortness of breath. Most people have mild cases of hMPV, but severe cases can result in bronchiolitis, bronchitis and pneumonia. hMPV is associated with approximately 20% of respiratory tract infections in children worldwide2. Up to 16% of the children infected with hMPV develop more severe symptoms3, with over 16,000 deaths worldwide in children under the age of five each year.4 Despite its prevalence and potential severity, there are currently no vaccines or antivirals approved to treat hMPV.5

2 https://www.sciencedirect.com/topics/immunology-and-microbiology/human-metapneumovirus

3 Howard LM, et al. 2021

4 Wang X, et al. 2021

5 CDC