Table 1. Summary of major topics and subthemes.

Summary of the overall themes identified illustrated with selected quotes.

Community benefits and risks
Facilitating development of vaccines and therapeutics	“That is an important point, especially for conditions being common in endemic areas, for which there are not enough sites to do Phase 3 studies for every vaccine.” “This type of research has potential when thinking about vaccine development.”
Pathogenesis research	“This model will allow us to explore why this person has severe illness, while the others have mild illness.”
The choice of challenge strains and their characteristics	“Yes, it is the difficulty we have. You have to prove that if you infect with the wild type and the experimental type, they have the same risks, the same virulence.”
Building and strengthening scientific and research capacity	“Building capacity involves developing clinical sites, laboratory sites and also regulatory and ethical aspects if they have wide relevance… in that way we see that we feel fascinated in investing in low and middle income countries.”
Potential secondary transmission and community exposure	“Screening people daily to be sure that they will not share the organisms when they leave. We cannot let people leave until we know that there is no risk for transmission to the community.”
Participant motivations and risks
Individual participant risk	“What about ethical issues? Do you think that exposing people to potentially dangerous pathogens is acceptable? There is a risk, a small risk, but it still exists, maybe minor than in other clinical trials or not.”
Immediate versus long-term risks	“They have been challenged, then they are healthy, and they go. Maybe a year or two later, they go for a holiday in some isolated islands and they get secondary infection in a place where they have no health care. That would be a risk.”
Reimbursement and risk compensation	“Personally, I may join the study for altruism. Maybe, or someone else. But how we can be sure that this is the true altruism? I think it is the most challenging question to me.”
Selection and consent of study participants	“Should we allow people to take that risk if they really understand it? Who makes the decision? Should it be individuals to make decisions or should it be authorities?”
Barriers and challenges
Regulatory and legal context	“How can these studies be conducted in Vietnam? And what we can do for that? You know that in Vietnam if you want to do anything related to human research, you must follow the regulations, the laws, the guidelines from MoH… I would like to propose OUCRU and the international experts, after this workshop, we can work closely together to prepare and develop the guidelines for human challenge studies in Vietnam.”
Ethical framework	“National Guidelines for Ethics in Biomedical Research were releases by MoH. In vaccine trials, this guideline requires vaccines to be tested in three phases. This guideline does not mention human challenge studies.”
Media and public perception	“In some ways, it may depend on what the article says, how the article represents the issues. You could have a journalist whose attitude is negative, or you may have a journalist who could say that this is a really important way to developing science to try and help Vietnamese people solve serious problems.”