New Typhoid Vaccine Shows 81% Effectivity in First Field Trial
Wed, April 21, 2021

New Typhoid Vaccine Shows 81% Effectivity in First Field Trial

A new vaccine for typhoid fever shows promising results following its first field trial in Nepal, providing a new opportunity to tackle the disease that affects millions of children worldwide / Photo by: OneSideProFoto via Shutterstock

 

A new vaccine for typhoid fever shows promising results following its first field trial in Nepal, providing a new opportunity to tackle the disease that affects millions of children worldwide.

Researchers from the University of Oxford, the University of Maryland School of Medicine, and the global health organization PATH convened to form the Typhoid Vaccine Acceleration Consortium (TyVAC). The consortium completed a large field study that tested the new vaccine—known as Typbar-TCV (Bharat Biotech)—in children in Nepal, and the results of which were published in the New England Journal of Medicine.

 

Promising Results of the Typbar-TCV

The study involved over 20,000 children aged nine months to 16 years old, who were randomly given either a new typhoid conjugate vaccine (TCV) or the Group A meningococcal (MenA) vaccine. The 10,014 children who received the MenA vaccine served as the control group.

In the TCV group of 10,005 children, only seven children were found to have a confirmed case of typhoid fever whereas the MenA group resulted in 38 cases. This shows that a single dose of the new vaccine reduced the disease by 81.6% in phase 3 controlled trial in Nepal, Healio reports.

Healio is a clinical news, information, and education website designed exclusively for specialty healthcare professionals, providing them with personalized content based on their needs and areas of interest.

It adds that the overall 132 serious events—61 in the TVC group and 71 in the control group—occurred in the first six months of the trial. Among that number, only one was confirmed as vaccine-related, and fever was observed in 5% of the children in the TVC and 5.4% in the MenA group in the first week of vaccination.

Seroconversion, or the time period during which a specific antibody develops and becomes detectable in the blood, in an immunogenicity group occurred in 677 of 683 (99%) in the TVC group and only eight of 380 children (2%) in the control group.

Healio stated that the Typbar-TCV offers immunity that lasts longer compared to older vaccines with few doses. The World Health Organization prequalified the new vaccine in December 2017, making it accessible to global health agencies for areas where the TCV is needed the most.

The results of the study "give confidence" that the new TCV could have a significant impact on typhoid and "improve the health of some of the most vulnerable children in the world," Andrew J. Pollard, professor of pediatric infection and immunity at the University of Oxford, told the clinical news site.

Saving Millions of Lives

The field trial was the first to demonstrate that a single dose of TCV is "safe, immunogenic, and effective," providing clear evidence that vaccination can help in controlling typhoid fever. Furthermore, the results demonstrate the vaccine's potential to significantly reduce the burden of the disease in high-risk populations.

This is crucial, especially now that some strains of the disease are becoming resistant to antibiotics especially in countries in South Asia. According to Medscape, a website providing medical information to clinicians, typhoid fever infects about 21.6 million people and is the cause of an estimated 200,000 deaths a year. 

It adds that 80% of typhoid fever cases come from countries like India, Nepal, Pakistan, or Vietnam—and the disease is most common in the underdeveloped areas of those countries. A press release states that TCVs can overcome many of the challenges that stopped the uptake of earlier vaccines.

This includes longer-lasting immunity, fewer doses, and suitability for children below two years old, allowing its inclusion in routine childhood immunity programs.

"The efficacy of these results in an endemic population adds to a growing body of evidence supporting the use of TCV to reduce disease and save lives in populations that lack clean water and improved sanitation," Kathleen Neuzil, director of TyVAC, said in the press release.

Pollard added that the data from the study lays the foundation for widespread acceptance and use of the new vaccine "wherever there is a high burden of typhoid in childhood."

Gauging the New Vaccine’s Effectiveness

There are currently two existing typhoid vaccines: One is a capsule given to children over six years old since it is too large for children below that age to swallow, and the other is delivered through injection and can only be given to children over the age of two.

This highlights another important aspect of the study's results: the age at which the vaccine was given. Since the Typbar-TCV was given to children as young as nine months, and with the high efficacy rate of the drug, it could provide people with young children the protection they need against typhoid—especially if they are prone to traveling to countries where the threat is particularly high.

However, additional observations are needed to determine how long the new vaccine protects against the disease, which is often spread through contaminated water in areas with poor sanitation.

Reuters reports that more two-year field tests are also being conducted in Bangladesh and Africa to test the vaccine's effectiveness in those countries.

There are currently two existing typhoid vaccines: One is a capsule given to children over six years old since it is too large for children below that age to swallow, and the other is delivered through injection and can only be given to children over the age of two / Photo by: PanyaStudio via Shutterstock