Typhoid Conjugate Vaccine Candidate Gets WHO Prequalification

SEOUL, KOREA — The typhoid conjugate vaccine (TCV) developed by SK bioscience with technology transfer from the International Vaccine Institute (IVI) has achieved the World Health Organization prequalification (PQ), paving the way for public procurement of the vaccine by UN organizations and gives a boost to the global TCV supply.

The WHO PQ certifies the safety, efficacy, and GMP of a vaccine by evaluating its manufacturing process, quality, and clinical trial results according to stringent standards. The WHO PQ is essential for participating in international tenders organized by UN agencies including UNICEF and the Pan American Health Organization (PAHO) and certifies the quality of the vaccine and the competitiveness of technology in the global market.

Efficacy and safety of the new typhoid conjugate vaccine

The new vaccine, SKYTyphoid™, which has received the WHO’s seal of approval this time, is a TCV developed jointly by SK bioscience and IVI following IVI’s technology transfer with funding support from the Bill & Melinda Gates Foundation. The vaccine utilizes the purified Vi polysaccharide–diphtheria toxoid (Vi–DT) method that conjugates diphtheria toxoid (acts as a carrier) to polysaccharide of typhoid bacteria (acts as the antigen). 

Adopting conjugation technology, the vaccine is safe to administer in infants and young children aged six months to two years. It is expected to provide sufficient immune response and long-term protection with a single dose, compared to existing oral live or polysaccharide typhoid vaccines.

Immunogenicity of SKYTyphoid™

A Phase 3 clinical trial conducted by SK bioscience and IVI in Nepal on 2,160 healthy individuals aged six months to 45 years confirmed the excellent immunogenicity and safety of the vaccine. 

In the comparative study with a conventional WHO-PQed polysaccharide–protein conjugate typhoid vaccine, SKYTyphoid™ demonstrated equivalent immunogenicity and safety, without any notable side effects after administration across all age groups. The findings were published in The Lancet Infectious Diseases.

Additionally, the results of the Phase 2 clinical trial of SKYTyphoid™ booster shot, published in npj Vaccines showed that two doses of the TCV in infants aged 6 to 23 months induced a strong immune response, with a significant increase in antibody titers in the body compared to before vaccination.

With the high demand for typhoid vaccines worldwide, especially in low-income countries, the company plans to start supplying the vaccine as soon as possible and expand global supply through public procurement markets, including typhoid-endemic countries. 

- This press release was originally published on the International Vaccine Institute website