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Influenza Challenge Studies

Experts leading the way in flu challenge studies

The Challenge

Seasonal influenza (“flu”) causes significant morbidity and mortality each year and a pandemic influenza continues to pose a worldwide threat. Government health agencies and a large number of academic, public and private organisations and consortiums are encouraging the development of universal / broad spectrum flu vaccines.

Novel correlates of protection are being explored, with humoral and cellular immune responses now more than ever at the forefront of vaccine research. The controlled human model of infection with contemporaneous wild-type influenza viral strains will play a unvaluable role in this development process and the rapid validation of new vaccine candidates.

Proven flu disease models
We have been studying influenza for over 20 years, conducting influenza human challenge studies with our flu disease models for more than 15 years.

We have delivered numerous flu challenge studies for a range of industry, governmental and academic partners, making our tool the most well-used commercial flu disease models available on the market.

As the industry leader in conducting human viral challenge studies, our team has developed a large Virobase, of clinical data paired with virological, host genetics and immunology data, combined with an extensive biorepository of blood and respiratory samples. This “Virometrics” resource, in conjunction with our unique insight into the host response to viral disease, allows us to tailor study designs to each Investigational Medicinal Product (IMP).

hVIVO developing first Influenza B Human Challenge Model

Influenza B stands as the second most prevalent strain of influenza virus responsible for seasonal flu outbreaks, trailing behind influenza A. Categorized into subtypes known as B/Yamagata and B/Victoria based on their lineages, these viruses were initially identified in 1940. Unlike some other strains, influenza B primarily affects humans, lacking a significant animal reservoir.

While influenza A finds greater prevalence among adults, accounting for roughly 75% of all influenza cases, influenza B tends to target children more frequently. Although it generally manifests as a mild to moderate illness in healthy pediatric populations, its severity increases among children under the age of 5. This heightened susceptibility might be attributed to their limited prior exposure and subsequently lower immunity.

Furthermore, there is evidence suggesting a rising potency of influenza B, potentially leading to heightened mortality rates compared to specific subgroups of influenza A, particularly in populations with compromised immune systems such as individuals living with HIV. Acknowledging the significance of influenza B is crucial, as its capacity to induce high morbidity and mortality rates should not be underestimated.

hVIVO’s CSO Dr. Andrew Catchpole on Influenza B

Experienced and engaged team with expertise in human challenge studies
Asian mid-size pharma client

Flu Vaccines

Conceptual Challenges:

Demonstrating efficacy of novel vaccines in the field is time-consuming, costly and associated with risk

  • Initial exposure to virus unknown
  • Variation in circulating strains
  • Large study size and long duration
  • Difficult to power for clinical efficacy
  • Seasonality limitations
  • Complicated Biomarker identification

Our Human Challenge Models: Towards a deeper understanding

  • Effective exploration of vaccine efficacy & correlates of protection
  • Match study design to IMP mechanism of action
  • Controlled Immunological investigation
  • Host Response Analysis

Primary Endpoints:

  • Reduction in incidence of symptomatic infection
  • Reduction in disease severity


Conceptual Challenges:

Establishing efficacy of antivirals in early clinical trials is challenging

  • Initial exposure to virus unknown
  • Dose ranging and timing difficult
  • Comorbidities and other confounders

Our Human Challenge Models: Towards a deeper understanding

Clinical proof of concept and dosing finding delivered in a controlled setting

  • Study design matched to IMP mechanism of action
  • Optimisation of treatment timing
  • Time-dependent measurements of biomarkers
  • Triggered-dosing options (symptoms or virological)
  • Controlled strain exposure
  • Consistent placebo response
  • Flu season independent
  • Efficient resistance monitoring
Influenza virus
A trialist for hVIVO/Flucamp


Conceptual Challenges:

Demonstrating clinical efficacy in early-stage field trials is challenging

  • Baseline prior to infection unachievable, difficult to establish host response
  • Effect with/without standard of care treatment difficult to establish
  • Large study size and duration
  • Seasonality limitations
  • Circulating strain variation
  • Biomarker identification difficult
  • Initial exposure to virus unknown

Our Human Challenge Models: Towards a deeper understanding

Clinical proof-of concept and dosing finding delivered in a controlled setting

  • Controlled quarantine environments
  • Baseline well established prior to infection
  • Appropriate for both prophylaxis and treatment
  • Flexible dosing and timing
  • Establish safety & efficacy to impact infected subjects host response
  • Investigate and demonstrate target engagement
  • Controlled combination-treatment with drug and standard of care or antivirals
Influenza Factsheet

Provide early human proof of concept and proof of efficacy data to support selection of best IMP candidates

Reduced costs as the model requires only a small number of subjects investigated over a shorter period of time to deliver an efficacy outcome

  • Study management

  • Deliver quality results (GCLP)

  • Meeting client needs and timelines

  • Trials conducted using controlled settings and processes

Bespoke quarantine unit in Whitechapel, London for conducting challenge studies:

  • 62 en-suite rooms

  • Well characterised challenge virus (GMP)

  • Exact exposure time to virus

  • Controlled dose of virus administrated

  • Quarantine discharge and follow up

  • Standard 28 days can be up to 1 year

  • Immunogenicity (e.g. PBMC)

  • Seroconversion and mucosal immunoglobulins

If you’re a potential customer, job seeker, health professional or an investor, find out how we can help you.

Contact hVIVO