WHO adopts “Human Challenge Trial” to develop new vaccine

The World Health Organization (WHO) recently announced eight candidates to enter human trials. Several people step forward to participate in human challenge trial as the race to develop new vaccine for the virus is increasing.

What is Human Challenge Trial?

The trial involves infecting volunteers intentionally with COVID-19 virus. This is done to speed up the process of vaccine development.

Vaccine Development

The Vaccine development takes several years to develop through three phases of clinical trials. This includes

Phase 1: During this phase small groups of people receive the vaccine

Phase 2: Vaccine is given to those people whose characteristics are similar to those for whom the new vaccine is intended.

Phase 3: Vaccine is given to several thousands to test the safety and efficacy. During this phase, the participants either receive placebo or vaccine. Placebo is something that looks like treatment but is not in reality. It can be a sugar solution or saline.

The Human Challenge Trial is not new. Earlier, similar trials were conducted for malaria as well.


The main benefit of the human challenge trial is that it accelerates testing. Many efficacious vaccines shall be available more quickly. Also, the number of people required in phase 3 of these trials is less than the regular trials.


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