hVIVO Signs Phase III Whooping Cough Vaccine Contract With ILiAD

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HCT contract signed with ILiAD Biotechnologies

HVIVO PLC Released 07:00:03 22 April 2026 RNS Number : 3809B hVIVO PLC 22 April 2026

hVIVO plc

("hVIVO", the "Company" or the "Group")

hVIVO to conduct world's first pivotal Phase III human challenge
whooping cough vaccine trial for ILiAD Biotechnologies

· World's first pivotal Phase III human challenge trial ("HCT") in Bordetella pertussis (the bacteria that causes whooping cough) for ILiAD Biotechnologies vaccine candidate, BPZE1

· hVIVO's largest HCT to date, with over 500 participants anticipated, with revenue recognition expected from H1 2026

· Trial expected to be hVIVO's largest value HCT to date; making a strong contribution to near and mid ‑ term revenues with the majority expected to be recognised during 2026 and 2027

London, UK - 22 April 2026, hVIVO plc (AIM: HVO), a purpose-built, full-service international clinical development partner and the world leader in human challenge trials, announces that it has signed a contract to conduct a pivotal Phase III human challenge trial for ILiAD Biotechnologies, Inc. ("ILiAD") to test its Bordetella pertussis (" B pertussis ") vaccine candidate, BPZE1.

The study will be the first ever pivotal B pertussis Phase III human challenge trial assessing BPZE1's efficacy in preventing infection (colonization) by B pertussis, a respiratory bacterium which causes whooping cough. The trial is anticipated to include over 500 healthy volunteers recruited through the Company's participant recruitment arm, FluCamp. This represents hVIVO's largest HCT to date, with BPZE1's efficacy being measured against the current standard of care Tdap combination vaccine.

HVIVO is expected to recognise revenue from H1 2026, with the majority of revenue recognised during 2026 and 2027. This multi-year contract will make a strong contribution to near- and mid ‑ term revenues. The Company has worked closely with ILiAD over the past year to develop the bacterial assays for this study, and hVIVO's bacterial laboratory in Canary Wharf will conduct the microbiology assay for the primary and key secondary endpoints of the trial. Given baseline pertussis vaccination rates and the unpredictability of B pertussis outbreaks, conventional pertussis vaccine field studies are unfeasible. HCTs offer a faster and more efficient pathway to pivotal efficacy data with fewer participants.

Whooping cough poses a significant risk, particularly for infants under six months of age, causing serious and sometimes life-threatening complications - outbreaks are cyclical but unpredictable and do not follow a seasonal pattern. In the UK, cases rose in 2024 by 17x versus 2023. 1 A study in 2017 estimated the global burden of B pertussis to be 24 million cases per year, with 160,000 deaths among young children. 2 Despite 85% vaccination coverage worldwide, 3 the efficacy of current vaccines is known to be relatively short-lived and as such the level of community protection is waning.

BPZE1 is a next-generation live attenuated needleless intranasal B pertussis vaccine designed to provide comprehensive and durable protection against B pertussis infection (colonisation) and disease (whooping cough). BPZE1 is being developed to block B pertussis from colonising the nasal passages of adults and children, to protect them from whooping cough, and potentially to prevent transmission, including transmission to vulnerable infants.

Yamin 'Mo' Khan, Chief Executive Officer of hVIVO, said: "This study represents a landmark moment for human challenge trials which can help to bring vital medicines to market faster. We are pleased that data generated from this trial will be used in ILiAD's future marketing applications for BPZE1 to the US FDA, UK MHRA, EMA and other global regulatory agencies, underlining the growing recognition that HCTs can deliver rapid and high-quality data supporting global licensures. This approach has the potential to accelerate the development of future vaccines and antiviral therapies, in other indications with unpredictable seasonality, ultimately, bringing important medicines to patients faster."

Dr. Keith Rubin, Chief Executive Officer of ILiAD Biotechnologies, said: "We greatly appreciate the partnership with hVIVO to initiate our pivotal Phase III human challenge trial for BPZE1, a vaccine with the potential to address a major global unmet medical need. This is a highly innovative, world-first Phase III human challenge trial, and we're confident that hVIVO has the experience and expertise to deliver a rigorous and well-executed study. We expect this trial to generate important pivotal data to form a core part of our global marketing authorisation applications for BPZE1 and to accelerate access to this urgently needed vaccine."

1 UKHSA, Confirmed cases of pertussis in England by month, 2024.

2 Yeung KH, Duclos P, Nelson EA, Hutubessy RC (September 2017). "An update of the global burden of pertussis in children younger than 5 years: a modelling study". The Lancet. Infectious Diseases. 17 (9): 974-980. doi:10.1016/S1473-3099(17)30390-0. ISSN 1474-4457. PMID 28623146

3 Childhood vaccination rates lag in Europe - fueling further resurgence of measles and whooping cough. Available at: https://www.unicef.org/moldova/en/press-releases/childhood-vaccination-rates-lag-europe-fueling-further-resurgence-measles-and

The information contained within this announcement is deemed by the Company to constitute inside information as stipulated under the Market Abuse Regulation ("MAR") EU no.596/2014. Upon the publication of this announcement via Regulatory Information Service ("RIS"), this inside information is now considered to be in the public domain.

For further information please contact:

| hVIVO plc | | +44 (0)20 7756 1300 |
| Yamin 'Mo' Khan, Chief Executive Officer

Stephen Pinkerton, Chief Financial Officer |

| Cavendish Capital Markets Limited (Nominated Adviser and Joint Broker) | +44 (0)20 7220 0500 |
| Geoff Nash, Callum Davidson
Trisyia Jamaludin, Harriet Ward

Nigel Birks - Life Science Specialist Sales

Louise Talbot - Sales |

| Peel Hunt LLP (Joint Broker) | +44 (0)20 7418 8900 | |
| James Steel, Dr Christopher Golden |

| Davy (Joint Broker) | +353 (0) 1 679 6363 | |
| Anthony Farrell, Niall Gilchrist |

| ICR Healthcare (Financial PR & IR)

Mary-Jane Elliott / Stephanie Cuthbert / Phillip Marriage / Louis Ashe-Jepson | | hVIVO@icrhealthcare.com |

Notes to Editors

hVIVO plc (AIM: HVO) is a purpose-built, full-service international clinical development partner and the global leader in human challenge trials, serving seven of the world's ten largest biopharma companies.

The Company has an end-to-end platform designed to bring important medicines to patients faster: spanning preclinical strategy, first‑in‑human studies, Phase II patient trials and specialist laboratory services, delivered through a large participant database, wholly owned sites and laboratories across the UK and Germany.

With a combined Group heritage of more than 100 years, hVIVO delivers an accelerated pathway to clinical proof-of-concept through four integrated service lines: Consulting, Clinical Trials, Human Challenge Trials, and Laboratories.

· Consulting provides expert-led preclinical and clinical strategy, encompassing non-clinical, clinical, CMC, pharmacokinetics, data management, biostatistics, and regulatory support to guide trial design, execution, and interpretation.

· Clinical Trials offers Phase I/II CRO services, Phase II/III site services across the UK and Germany, and specialist recruitment through FluCamp, Europe's largest recruitment database.

· Human Challenge Trials leverages hVIVO's state-of-the-art quarantine facility in London - the largest of its kind worldwide - to deliver fast, controlled, high-quality efficacy data through guaranteed viral exposure.

· Laboratories provides cutting-edge virology and immunology laboratory services, including biobanking and sample storage, supporting both challenge trials and standalone client studies.

About ILiAD Biotechnologies, LLC

ILiAD Biotechnologies (http://www.iliadbio.com) is a privately held, late clinical stage biotechnology company dedicated to the prevention and treatment of human disease caused by Bordetella pertussis. The company is developing and acquiring key technologies, working with leading scientists to overcome the limitations of current vaccines, investigating the impact of B. pertussis in a range of human disease, and is focused on validating its proprietary vaccines in human clinical trials.

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