Typhoid Vaccines 2023
The U.S. Centers for Disease Control and Prevention (CDC) recommends typhoid vaccination for people traveling to places where typhoid fever is common, such as South Asia, especially India, Pakistan, and Bangladesh. However, typhoid vaccines are not 100% effective. On June 16, 2023, the CDC issued a Level 1 travel advisory for an extensively drug-resistant (XDR) typhoid fever outbreak.
The World Health Organization (WHO) recommends safe, effective typhoid conjugate vaccines (TCV) for typhoid fever control. Since 2018, five countries have introduced TCV into their national routine immunization schedule. In the U.S., two types of typhoid fever vaccines are available. If you were vaccinated in the past, ask your doctor or pharmacist if it is time for booster vaccination, says the CDC. In November 2023, the Lancet Infectious Diseases published - typhoid's transformation from an environmental to a vaccine-preventable disease, 1940–2019.
Types of Typhoid Vaccines
Oral vaccine: Can be given to people at least six years old. It consists of four pills taken every other day, should be finished at least one week before travel, and requires a booster every five years.
Injectable vaccine: Can be given to people at least two years old and should be given at least two weeks before travel, and requires a booster every two years.
Bharat Biotech International's Typbar TCV is a vaccine containing polysaccharides of Salmonella typhi Ty2 conjugated to Tetanus Toxoid.
Sanofi Pasteur's Typhim VI is a sterile solution prepared from the purified polysaccharide capsule of Salmonella typhi (Ty 2 strain).
Emergent BioSolutions' Vivotif oral vaccine is indicated for immunization of adults and children over six years of age against disease caused by Salmonella Typhi.
SK bioscience SKYTyphoid™ is a polysaccharide-protein conjugate vaccine developed by conjugating the polysaccharide of typhoid bacteria, which acts as the antigen, to the diphtheria toxin protein (diphtheria toxoid), which acts as a carrier. Phase III Vi-DT typhoid conjugate vaccine trials are scheduled in Nepal and the Philippines.
Typhoid Fever Vaccine Research 2023
August 23, 2023 - SK bioscience is developing a second-generation typhoid conjugate vaccine with support from Wellcome.
May 12, 2023 - Malawi has launched a nationwide rollout of the newest typhoid vaccine for children under 15 years of age.
February 17, 2023 - The U.S. CDC says to guide evidence-based TCV introduction decisions, countries with endemic typhoid should consider all available information, including surveillance of laboratory-confirmed cases, population-based and modeling studies, and outbreak reports. Establishing and strengthening typhoid fever surveillance will be essential to measure vaccine impact.
January 9, 2023 - Study: Identification of Multiple Variants of Extensively Drug-Resistant Typhoid Infections across Pakistan. These results can inform containment initiatives, help track associated outcomes and international spread, and help determine the overall risk.
September 1, 2022 - The Lancet Global Health published a study: Safety and immunogenicity of a typhoid conjugate vaccine among children aged nine months to 12 years in Malawi: a nested substudy of a double-blind, randomized controlled trial. Interpretation - This study provides evidence of TCV safety, tolerability, and immunogenicity up to 730–1035 days in Malawian children aged nine months to 12.
June 21, 2022 - The peer-reviewed journal The Lancet Microbe published - The International and Intercontinental Spread and Expansion of Antimicrobial-resistant Salmonella Typhi: a genomic epidemiology study, which found evidence of frequent international and intercontinental transfers of antimicrobial-resistant S Typhi, followed by local expansion and replacement of drug-susceptible clades. This study shows how typhoid-resistant strains from Southern Asia have spread to other countries almost 200 times since 1990.
September 16, 2021 - Study results: Typhoid conjugate vaccines are highly effective in African children. Those children who had received TCV were 84% less likely to contract typhoid during that time.
July 29, 2022 - Review of the Recent Advances in Typhoid Vaccine Development and Challenges Ahead.
October 30, 2019 - Clinical Infectious Disease published - The Severe Typhoid Fever in Africa Program: Study Design and Methodology to Assess Disease Severity, Host Immunity, and Carriage Associated With Invasive Salmonellosis - Currently available typhoid vaccines include the parenteral unconjugated Vi polysaccharide and oral live-attenuated Ty21a vaccines, both of which have been recommended by the WHO since 2008, and parenteral typhoid conjugate vaccine, which the WHO prequalified in December 2017.
Typhoid Wastewater Detection 2023
The journal Nature reported that a team in Bangladesh collected water samples from sites in Dhaka and Mirzapur between August and December 2021. Samples of less than 10 milliliters were filtered to remove bacteria and large debris. The water was then dropped onto colonies of S. Typhi growing in 'lawns' in a Petri dish. If typhoid-specific bacteriophages were present, they killed the bacterium, forming clear patches in lush lawns.
A similar approach is routinely used to test water for fecal contamination by screening for Escherichia coli and Bacteroides fragilis, bacteria commonly found in people's guts, says James Ebdon, an environmental microbiologist at the University of Brighton, UK. However, this is probably the first time scientists have used the approach to identify typhoid.