A new vaccine could prevent more than half of typhoid infections, researchers report today.
The vaccine, currently only licensed in India for infants, is safe and highly immunogenic, according to a phase 2b study, reported in The Lancet.
The randomised control trial of Vi-conjugate vaccines was conducted using a controlled human infection procedure.
It used healthy volunteers, exposed to the pathogen after vaccination or exposure to a control vaccine.
The volunteers at Oxford University, UK, received a Vi-tetanus toxoid conjugate vaccine or the pre-existing Vi-polysaccharide vaccine or a meningococcal vaccine as a control.
About a third of those who received the Vi-conjugate vaccines developed typhoid compared with 77% of those in the control group. Those who received the Vi-TT experienced the least severe symptoms.
Researcher Professor Andrew Pollard said: “Since the 1960s, controlled human infection models have been used to evaluate the efficacy of typhoid vaccine candidates, successfully supporting the development of one of the currently licenced typhoid vaccines Ty21a. 60 years on, we have used the same type of study to show that a Vi-conjugate vaccine is safe, immunogenic and halves the total number of typhoid infection cases, with the protective effect of the vaccine in endemic settings likely to be much higher.
“Our study provides further evidence to support the development of Vi-conjugate vaccines as a control measure to reduce the burden of typhoid fever, and individuals living in endemic regions should not be made to wait another 60 years to receive the vaccine.”
Lancet 29 September 2017 [abstract]
Leave a Reply