Typhoid Fever (also known as typhoid) is a life-threatening infection caused by the bacterium Salmonella Typhi. It is usually spread through contaminated food or water. The World Health Organisation (WHO) estimates the global typhoid fever disease burden at 11-20 million cases annually, resulting in about 128,000–161,000 deaths per year. If typhoid is not treated, it can kill up to 30% of those who are infected.
Symptoms include prolonged high fever, fatigue, headache, nausea, abdominal pain, and constipation or diarrhoea. Some patients may have a rash. Severe cases may lead to serious complications or even death.
Typhoid affects populations in Africa, the Americas, South-East Asia and the Western Pacific regions. Populations that lack access to safe water and adequate sanitation are at higher risk. Vulnerable groups, including children are at highest risk; almost a third of all Typhoid Fever cases are among children under five years of age.
With appropriate antibiotic treatment, the case fatality rate of typhoid fever can drop to less than 1%. However, in recent years there has been an alarming increase in antimicrobial resistance of Salmonella Typhi.
Two vaccines have been used for many years to protect people from typhoid fever. One is an injectable vaccine based on the purified antigen for people aged over 2 years. The other is a live attenuated oral vaccine in capsule formulation for people aged over 5 years. These vaccines do not provide long-lasting immunity and are not approved for children younger than 2 years old. A new typhoid conjugate vaccine, with longer lasting immunity, was prequalified by WHO in December 2017 for use in children from the age of 6 months.
Following the Strategic Advisory Group of Experts (SAGE) recommendations in 2017, the Gavi Board approved US$85 million in funding, for typhoid conjugate vaccines starting in 2019.