We are excited to see the recent announcement of the Wellcome funded vivax malaria human infection study in Thailand! This article outlines how vaccines can be developed for populations most in need.

Vaccines are among the most successful and cost-effective healthcare interventions in human history, freeing people and entire populations from the fear of many infectious diseases. But there are many life-threatening diseases that we don’t have vaccines for – and some of the vaccines we do have are not as effective as they should be.

Human infection studies speed up vaccine development and reduce the burden of some of the world's most crippling diseases.  The studies involve vaccinating healthy volunteers and then deliberately exposing them to the infection, in a controlled and safe setting, to test whether the vaccine works. 

Human infection studies can give us an indication that a vaccine is effective far more quickly than would be possible through large-scale population trials.This can address specific disease related questions and accelerate vaccine development and design. Studies are most appropriate for diseases where no suitable animal models exist and are only used when there’s already some form of treatment for the disease.

Human infection studies can take place anywhere there are people. They can focus on populations where a disease is endemic, helping to test and develop effective vaccines and treatments for communities most at risk. Another benefit is that the studies produce highly-detailed information. They are performed under controlled conditions, so the timing of infection is known. The volunteer’s health is monitored to see how the disease is progressing and how their body is responding to the treatment or vaccine being tested. Safety of the volunteers is paramount and therefore these studies are subject to stringent ethical review and regulatory oversight.

These studies have already provided landmark data for several registered vaccines. One example is the Vi-TT (Vi-tetanus toxoid conjugate vaccine) for which data obtained through a human infection study contributed to the World Health Organization’s decision to recommend the vaccine for use in all ages.

Currently the majority of human infection studies are performed in the United States and Europe. However, studies have shown that there can be significant variation in immune response and thus vaccine efficacy between populations in different geographical and epidemiological settings. Therefore developing a vaccine in  low resource settings specifically will allow efficacious vaccines to be developed rapidly and reduce the burden of disease. This is where human infection studies are playing an increasing important role and the field has rapidly expanded over recent years, with sites active across Africa and Asia.

The recent announcement of a vivax malaria human infection study at the Mahidol Oxford Tropical Medicine Research Unit, Thailand is an exciting development for the field of malaria. This will greatly accelerate and incentivise the development of a vaccine for a pathogen that caused 8.5 million cases of malaria in 2016 alone with 58% of the global vivax burden occurring in South-East Asia.

In addition to the vivax malaria human infection study in Thailand Wellcome plans to support the establishment of a portfolio of human infection studies in low resource endemic settings so that the development of vaccines can be accelerated for populations that need them most.

And for more information on Wellcome’s funding programme for human infection studies and activities, see https://wellcome.ac.uk/vaccines

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