Challenge Trials and the Efficacy of Vaccines
Human challenge studies, also called challenge trials or controlled human infection models are types of carefully managed clinical research studies. During these challenge trials volunteers are intentionally exposed to an infectious agent in a safe manner. This is usually done in a controlled setting with close medical supervision, using either very low doses of infective agents or strains that are attenuated and therefore safe.
Human challenge trials have a unique ability to investigate the onset and development of disease in a controlled environment. They allow the analysis of the efficacy of anti-infective treatment or vaccination in a rather small study group within a short time span.
How Challenge Trials Work
In the case of vaccines, traditional clinical evaluation involves the vaccination of a high number of individuals. For example, vaccination is carried out before the influenza epidemics, and analysis is done several months later. As only a small percentage of volunteers will be infected in real life, a high number of volunteers is needed to reach statistical significance and prove the efficacy of a vaccine. In challenge trials, the rate of infection is pre-defined. The onset of symptoms in the volunteers occurs immediately after the challenge. Therefore, these challenge trials are quite fast and reach statistical significance with a low number of subjects.
Especially in times of urgent need for vaccines as in pandemic situations, human challenge trials allow the acceleration of the development of vaccines. In 2021, the United Kingdom approved the world’s first coronavirus human challenge study, in which volunteers were exposed to the virus for research purposes. The World Health Organization (WHO) has published a guidance detailing the use of human challenge trials in vaccine development. Today, an international network of researchers developing human infection challenge studies helps to accelerate the development of vaccines against pathogens of high global impact.
Nuvonis Provides GMP Cell Banks for Challenge Virus Production
Attenuated pathogens are often used in challenge trials, and those strains (e.g. SARS-CoV-2 or influenza) can be produced in cell culture. Vero cells are a well-proven cell substrate for the generation of such challenge viruses. Therefore, providing high-quality GMP Vero cells is an important prerequisite for the fast production of challenge virus strains that are used in clinical trials. Nuvonis has provided Vero cells for several viruses that were used in clinical trials, demonstrating the high-quality standard of its GMP cell banks. The full characterization according to ICH guidelines, the thorough description of the history, passage level and GMP manufacturing of Nuvonis Vero Cell Banks is of utmost importance for the production of such challenge viruses. They are essential tools for vaccine research.
In addition to Vero cells, Nuvonis also offers a new cell substrate for the production of viruses that can be grown in avian cell lines. The CCX.E10 avian (quail) cell line is a versatile substrate that grows under serum/animal component-free conditions in suspension and is now widely tested and used in virus/vector manufacturing. Fully tested and released GMP Working Cell Bank ampoules of CCX.E10 are immediately available for challenge trials and challenge virus production at contract manufacturing organizations (CMOs).