Vaccine Challenge Studies

The rise in emerging diseases, bioterrorism, resistance to existing antimicrobials, and the apparent increase in virulence of some viruses (e.g., influenza, SARS, and coronavirus) has spurred the drive to develop new prophylactic vaccines.

Vaccine challenge studies involve the deliberate infection of a healthy host and allow for:

  • A greater understanding of the infecting pathogen in terms of identifying both the cellular and systemic targets of the infective
  • Estimating the potency/efficacy of either the prophylactic or therapeutic treatment product

Many ethical and safety considerations need to be addressed for vaccine challenge studies, and assessment is dependent on the pathogen in terms of biosafety level, virulence, route of administration, and host species.

Vaccine Challenge Studies – Services and Experience

For companies developing influenza, RSV, and COVID-19 vaccines, we have a wealth of experience in conducting both short- and long-term vaccine challenge studies in a wide variety of animals, including ferrets and rodents (mice, rats, guinea pigs, hamsters, etc.) under BSL-2 containment.

Hemagglutination assay (HA), hemagglutination inhibition assay (HIA), EID50 (50% embryo infectious dose) testing, and median tissue culture infectious dose (TCID50) can also be conducted on samples generated during vaccine challenge studies. We can also prepare tissues and samples, both in life and postmortem, and subcontract additional diagnostic and investigative analysis to one of our many sister facilities (histology, immunocytochemistry, viral titer of nasal washes, etc.).

  • Services
    • Various models available, including a vaginal candidiasis rat model
    • Use of individually ventilated cages (IVCs)
    • In-house microbiology department
    • Characterization of challenge material
    • Exploratory studies with the isolate
    • Evaluation of candidate antigens for bacterial challenge studies
    • Viral challenge studies and adjuvant selection testing
    • Short- and long-term influenza studies in ferrets and rodents
  • Experience
    • Antibiotics
    • Antifungals
    • Antivirals
    • Medical countermeasures (MCMs), including for botulinum toxin in all seven serotypes

With over 20 years of experience, we have the ability to conveniently reach across our Biologics testing portfolio to offer you more solutions, create more efficiencies, and expedite your drug development timelines.

Frequently Asked Questions (FAQs) about Vaccine Challenge Studies

  • What is a vaccine challenge test?

    A vaccine challenge test is a study of the efficacy of a vaccine by testing the immunized host with the pathogen of interest.

  • What is a hemagglutination inhibition test procedure?

    Hemagglutination inhibition tests are very simple tests that are quick and inexpensive to run. They are often used for assessing the level of influenza virus antibodies in a blood sample. In its simplest form, serum is diluted and incubated with the virus of interest; erythrocytes are then added to this mixture and the solution is incubated. The HI titer is determined to be the highest dilution of serum that prevents or inhibits hemagglutination from occurring. A fourfold or greater increase in HI antibody titer is considered evidence of infection.

  • What is a hemagglutination inhibition assay (HIA)?

    The hemagglutination inhibition assay (HIA) measures serum antibody directed against a hemagglutinating virus. The hemagglutination titer is the highest dilution of serum that completely inhibits hemagglutination by a standardized viral preparation. A hemagglutination inhibition assay (HIA) relies on the ability of the hemagglutinin protein on the surface of influenza virus to bind to sialic acids on the surface of red blood cells (RBCs). If the patient's serum contains antibodies that block viral attachment, this interaction is inhibited.