Typhoid Vaccine Provides Multi-Year Immunity in Children

Typbar TCV vaccine immunity in children can last three years
happy children
by Ian Ingalula
Malawi (Precision Vaccinations News)

An early release study published today in The Lancet Global Health found the typhoid conjugate vaccine, Typbar TCV®, can offer disease immunity for up to three years in children as young as nine months old.

The phase 3 research conducted in the African country of Malawi found that the TCV vaccine is safe and well tolerated.

Notably, the TCV vaccine can be administered to nine-month-old infants simultaneously as measles-rubella vaccinations without reducing the immune response to either vaccine.

These immunogenicity data can support TCV vaccine introduction in typhoid-endemic countries without data, which is essential, particularly in sub-Saharan Africa, where young children carry a high burden of typhoid fever, stated these researchers.

Typhoid causes more than nine million cases and at least 110,000 deaths yearly.

"It is simply amazing that a single dose of TCV will protect Malawian children for years," said Ngina Nampota, MBBS, MS, lead author of the new research and Study Physician with the Blantyre Malaria Project, an affiliate of Kamuzu University of Health Sciences, Malawi, in a press release on August 10, 2022.

Although whole-cell and polysaccharide typhoid vaccines have been available since the 1980s, uptake in endemic regions has been hindered by moderate and short-lived vaccine protection. 

Bharat Biotech International's Typbar TCV contains the Vi-antigen polysaccharide conjugated to a tetanus-toxoid protein carrier that reached WHO prequalification in 2017.

In 2018, the WHO recommended a single-dose TCV for the control of typhoid fever beginning as early as six months of age in typhoid-endemic regions, with priority in countries with the highest typhoid burden disease or a high burden of antimicrobial-resistant S Typhi.

This recommendation was made based on safety and immunogenicity data from a study on Asian children and efficacy data from an adult human challenge study in the U.K.

At the time of this phase 3 trial, there was no data from Africa on TCV efficacy and immunogenicity, including coadministration of TCV with routine vaccines at nine months of age.

However, the response might differ based on regional demographic, environmental, and genetic factors and coadministration with other vaccines.

The next steps are to assess the effect of a booster dose on long-term protection from typhoid fever in children.

While researchers continue to monitor the children vaccinated as part of this study, previous research suggests that TCV protection likely lasts at least five years.

"Our team's goal to protect children against typhoid represents a long-term aim of scientists working across the globe," commented Mark T. Gladwin, M.D., V.P. for Medical Affairs, UM Baltimore, and Dean at UMSOM.

"We are proud of these life-saving accomplishments of scientists in the University of Maryland's Center for Vaccine Development and Global Health, who focus on global efforts to reduce health care disparities."

The Bill & Melinda Gates Foundation partially funded this study with grant OPP1151153.

And this phase 3 study was supported by TyVAC – a partnership between CVD, the Oxford Vaccine Group at the University of Oxford, and the global non-profit PATH. TyVAC was initiated in 2016 as a multi-country project to accelerate the introduction of the TCV vaccine in Gavi-eligible countries.

Typbar TCV® is licensed by Bharat Biotech International Limited, Hyderabad, India.

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Article by
Donald Hackett