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First Typhoid Conjugate Vaccine Recommended by WHO

APR 03, 2018 | CONTAGION® EDITORIAL STAFF
The World Health Organization (WHO) announced today that they are recommending a typhoid conjugate vaccine (TCV), Typbar-TCV, for use in infants and children >6 months old in those countries where the infection is endemic. Typhoid affects nearly 12 million individuals and is responsible for about 128,000 to 161,000 deaths each year, according to the WHO.

These recommendations come on the heels of a review of the vaccine by the WHO’s Strategic Advisory Group of Experts (SAGE) on Immunization in October 2017. According to a statement released by the Typhoid Vaccine Acceleration Consortium, "The group considered data on vaccine safety, efficacy, feasibility, and affordability, as well as the growing rates of drug-resistant typhoid. Based on these discussions, SAGE recommended TCVs for children over the age of 6 months. These recommendations were accepted and reported in the WHO updated position paper on typhoid vaccines in the Weekly Epidemiological Report published on March 30, 2018."

Dr. Adwoa Bentsi-Enchill, medical officer of the Department of Immunization, Vaccines and Biologicals at WHO spoke about the vaccine in the statement, "Studies have shown that the TCV is safe, effective, and can provide protection for infants and children under 2 years of age, unlike the previously available typhoid vaccines. The recommendation for the typhoid conjugate vaccine to be included in routine immunization programs will help pave the way for national authorities to introduce this vaccine in countries where they are needed most." This new vaccine provides longer-lasting protection and fewer doses. 

In countries where the disease is endemic, a vaccine is paramount to controlling it. To this end, the WHO recommends a single dose of the TCV in infants and children >6 months. Furthermore, the WHO recommends "catch-up" vaccination in children up to 15 years in endemic countries. According to the statement, "the position paper recommended prioritizing TCV introduction in countries with the highest burden of disease or a growing burden of drug-resistant typhoid. TCV was also recommended as a response to confirmed typhoid outbreaks and for specific groups of people at high risk or with high transmission potential, including travelers from non-endemic to endemic areas. "

The WHO believes that "expanding coverage of TCV through routine immunization would reduce disease incidence and potentially decrease the need for antibiotics—2 priorities of the effort to stem the development and spread of drug-resistant typhoid," according to the statement. In addition, the organization highlighted the vaccine "as a critical tool to slow further emergence of drug-resistant typhoid strains and ultimately save lives."

Dr. Kathy Neuzil, director of the Center for Vaccine Development at the University of Maryland School of Medicine spoke about the importance of a vaccine against typhoid in the statement, "Typhoid fever is a familiar public health problem in many developing countries where rapid urbanization and an alarming increase of multidrug-resistant typhoid are creating an urgent need to focus on prevention. These WHO recommendations are a vital step to delivering TCVs to those who need them most and relieving the pressure on public health systems tasked with treating drug-resistant strains."

Caused by the bacterium Salmonella entericaserotype typhi, typhoid is a water-borne infection that is spread through contaminated food and water. Symptoms of the infection include a “high fever [103° to 104° F (39° to 40° C], weakness, stomach pains, headache, or loss of appetite. In some cases, patients have a rash of flat, rose-colored spots,” according to the Centers for Disease Control and Prevention (CDC). Without therapy, the illness can last anywhere from 3 to 4 weeks, according to the CDC, and the death rate ranges between 12% and 30%. Fluoroquinolones such as ceftriaxone and azithromycin are used to treat susceptible infections; however, a rise in antibiotic strains of the virus necessitates the introduction of a viable vaccine, especially for the most vulnerable populations, infants and young children.

Typbar-TCV achieved WHO prequalification in December 2017, a step which allows the WHO, United Nations Children's Fund, and other United Nations procurement agencies to purchase the vaccine. Additionally, "Prequalification serves as an endorsement of quality, efficacy, and safety for countries interested in adopting the vaccine. It enables eligible countries to receive funding assistance from Gavi, the Vaccine Alliance, which recently approved US$ 85 million to support the introduction of TCVs. Gavi-supported countries can now apply; introduction of the vaccine is anticipated by mid-2019," according to the statement.
 
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