SK bioscience’s typhoid conjugate vaccine achieves WHO prequalification

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

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. 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.

The new vaccine SKYTyphoid™, which has received the WHO’s seal of approval this time, is a typhoid conjugate vaccine developed jointly by SK bioscience and IVI following IVI’s technology transfer with funding support from the Bill & Melinda Gates Foundation. SK bioscience was the manufacturing partner and IVI led clinical trials conducted in the Philippines and Nepal.

Conjugation technology

The vaccine utilizes the ‘purified Vi polysaccharide-diphtheria toxoid conjugate’ method, which conjugates diphtheria toxin protein (diphtheria toxoid), which acts as a carrier, to polysaccharide of typhoid bacteria, which acts as an antigen. Adopting conjugation technology, the vaccine is safe to administer in infants and young children aged 6 months to 2 years and is expected to provide sufficient immune response and long-term protection with a single dose compared to existing oral live or polysaccharide typhoid vaccines. 

Based on clinical results, SKYTyphoid™ obtained a licensure for export from the Korean Ministry of Food and Drug Safety in 2022. A Phase 3 clinical trial conducted by SK bioscience and IVI in Nepal on 2,160 healthy individuals aged 6 months to 45 years had 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 effect after administration across all age groups. The findings were published in The Lancet Infectious Diseases.

Additionally, the results of the Phase II clinical trial of SKYTyphoid™ booster shot, published in the international ‘npj Vaccine,’ 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.

Global partnership

Dr. Sushant Sahastrabuddhe, Director of IVI’s Typhoid program, said: “The WHO licensure of SK bioscience’s TCV represents the successful conclusion of a global public-private partnership to bring a novel vaccine crucial to global public health to market. SKYTyphoid™ will diversify and expand the supply of TVCs and help improve vaccine access in the endemic countries. With SK’s commitment to make the vaccine for global public health at a competitive price, SKYTyphoid™ will play an important role in typhoid prevention globally.”

With high demand for typhoid vaccines worldwide, especially in low-income countries, SK bioscience plans to start supplying the vaccine as soon as possible and expand global supply through public procurement markets including typhoid endemic countries. According to the WHO, an estimated 11 to 20 million typhoid fever cases occur worldwide every year, and 120,000 to 160,000 die from the disease.

Climate change

Dr. Jerome Kim, Director General of IVI said, “Typhoid fever is more prevalent in warmer temperatures, and climate change and the worrying rise of antimicrobial resistance are only adding to the threat of the disease. Vaccination is critical to effective prevention and control of the disease. In collaboration with SK bioscience and other partners, IVI will continue endeavors to make this vaccine accessible to people who need them the most.”

Mr. Jae-Yong Ahn, President of SK bioscience said, “We are pleased that our global collaboration to address the global vaccine supply imbalance and improve public health has been recognized through the WHO PQ. In addition to the WHO PQ, we will obtain additional country-specific approvals to ensure that the vaccine can be supplied quickly.” With the addition of ‘SKYtyphoid™,’ SK bioscience has now achieved WHO PQ for four vaccines, including two influenza vaccines and a chickenpox vaccine.