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Journal of the Pediatric Infectious... Sep 2023We assessed anti-Vi IgG/IgA responses to typhoid conjugate vaccine (TCV) in children enrolled in a double-blind randomized controlled, phase 2 trial in Burkina Faso.... (Randomized Controlled Trial)
Randomized Controlled Trial
We assessed anti-Vi IgG/IgA responses to typhoid conjugate vaccine (TCV) in children enrolled in a double-blind randomized controlled, phase 2 trial in Burkina Faso. Anti-Vi IgG seroconversion and anti-Vi IgA titers were higher in TCV than control recipients at 30-35 months post-vaccination. TCV induces durable immunity in Burkinabe children vaccinated at 15 months.
Topics: Humans; Child; Infant; Typhoid Fever; Vaccines, Conjugate; Typhoid-Paratyphoid Vaccines; Burkina Faso; Antibody Formation; Immunoglobulin A; Immunoglobulin G; Antibodies, Bacterial
PubMed: 37589596
DOI: 10.1093/jpids/piad058 -
PLoS Neglected Tropical Diseases Feb 2024Typhoid-conjugate vaccines (TCVs) provide an opportunity to reduce the burden of typhoid fever, caused by Salmonella Typhi, in endemic areas. As policymakers design...
Typhoid-conjugate vaccines (TCVs) provide an opportunity to reduce the burden of typhoid fever, caused by Salmonella Typhi, in endemic areas. As policymakers design vaccination strategies, accurate and high-resolution data on disease burden is crucial. However, traditional blood culture-based surveillance is resource-extensive, prohibiting its large-scale and sustainable implementation. Salmonella Typhi is a water-borne pathogen, and here, we tested the potential of Typhi-specific bacteriophage surveillance in surface water bodies as a low-cost tool to identify where Salmonella Typhi circulates in the environment. In 2021, water samples were collected and tested for the presence of Salmonella Typhi bacteriophages at two sites in Bangladesh: urban capital city, Dhaka, and a rural district, Mirzapur. Salmonella Typhi-specific bacteriophages were detected in 66 of 211 (31%) environmental samples in Dhaka, in comparison to 3 of 92 (3%) environmental samples from Mirzapur. In the same year, 4,620 blood cultures at the two largest pediatric hospitals of Dhaka yielded 215 (5%) culture-confirmed typhoid cases, and 3,788 blood cultures in the largest hospital of Mirzapur yielded 2 (0.05%) cases. 75% (52/69) of positive phage samples were collected from sewage. All isolated phages were tested against a panel of isolates from different Salmonella Typhi genotypes circulating in Bangladesh and were found to exhibit a diverse killing spectrum, indicating that diverse bacteriophages were isolated. These results suggest an association between the presence of Typhi-specific phages in the environment and the burden of typhoid fever, and the potential of utilizing environmental phage surveillance as a low-cost tool to assist policy decisions on typhoid control.
Topics: Humans; Child; Typhoid Fever; Bacteriophages; Bangladesh; Salmonella typhi; Typhoid-Paratyphoid Vaccines; Water
PubMed: 38358956
DOI: 10.1371/journal.pntd.0011822 -
Vaccine Mar 2024Previously, the Vi-typhoid conjugate vaccine (Vi-TT) was found to be highly efficacious in Nepalese children under 16 years of age. We assessed the immunogenicity of...
BACKGROUND
Previously, the Vi-typhoid conjugate vaccine (Vi-TT) was found to be highly efficacious in Nepalese children under 16 years of age. We assessed the immunogenicity of Vi-TT at 9 and 12 months of age and response to a booster dose at 15 months of age.
METHODS
Infants were recruited at Patan Hospital, Kathmandu and received an initial dose of Vi-TT at 9 or 12 months of age with a booster dose at 15 months of age. Blood was taken at four timepoints, and antibody titres were measured using a commercial ELISA kit. The primary study outcome was seroconversion (4-fold rise in antibody titre) of IgG one month after both the doses.
FINDINGS
Fifty children were recruited to each study group.Some visits were disrupted by the COVID19 pandemic and occurred out of protocol windows.Both the study groups attained 100 % IgG seroconversion after the initial dose. IgG seroconversion in the 9-month group was significantly higher than in the 12-month group (68.42 % vs 25.8 %, p < 0.001). Among individuals who attended visits per protocol, IgG seroconversion after the first dose occurred in 100 % of individuals (n = 27/27 in 9-month and n = 32/32 in 12-month group). However, seroconversion rates after the second dose were 80 % in the 9-month and 0 % in the shorter dose-interval 12-month group (p < 0.001) (n = 16/20 and n = 0/8, respectively).
INTERPRETATION
Vi-TT is highly immunogenic at both 9 and 12 months of age. Stronger response to a booster in the 9-month group is likely due to the longer interval between doses.
Topics: Child; Infant; Humans; Typhoid Fever; Vaccines, Conjugate; Typhoid-Paratyphoid Vaccines; Nepal; Immunity; Immunoglobulin G; Antibodies, Bacterial; Immunogenicity, Vaccine
PubMed: 38395723
DOI: 10.1016/j.vaccine.2024.02.010 -
The Lancet. Global Health Mar 2024
Topics: Humans; Typhoid Fever; Anti-Bacterial Agents; Bayes Theorem; Drug Resistance, Bacterial; Salmonella paratyphi A; Paratyphoid Fever
PubMed: 38365399
DOI: 10.1016/S2214-109X(24)00030-5 -
PLoS Neglected Tropical Diseases May 2024
Topics: Salmonella paratyphi A; Paratyphoid Fever; Vaccines, Attenuated; Typhoid-Paratyphoid Vaccines; Flagella; Animals; Humans; Mice; Antibodies, Bacterial
PubMed: 38709719
DOI: 10.1371/journal.pntd.0012160 -
The Lancet. Global Health Apr 2024
Topics: Humans; Typhoid Fever; Typhoid-Paratyphoid Vaccines; Vaccines, Conjugate; Africa South of the Sahara
PubMed: 38485416
DOI: 10.1016/S2214-109X(24)00079-2