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Chikungunya can have longstanding effects on health and quality of life. Alongside the recent approval of the world's first chikungunya vaccine by the US Food and Drug Administration in November 2023 and with new chikungunya vaccines in the pipeline, it is important to understand the perspectives of stakeholders before vaccine rollout. Our study aim is to identify key programmatic considerations and gaps in Evidence-to-Recommendation criteria for chikungunya vaccine introduction. We used purposive and snowball sampling to identify global, national, and subnational stakeholders from outbreak prone areas, including Latin America, Asia, and Africa. Semi-structured in-depth interviews were conducted and analysed using qualitative descriptive methods. We found that perspectives varied between tiers of stakeholders and geographies. Unknown disease burden, diagnostics, non-specific disease surveillance, undefined target populations for vaccination, and low disease prioritisation were critical challenges identified by stakeholders that need to be addressed to facilitate rolling out a chikungunya vaccine. Future investments should address these challenges to generate useful evidence for decision-making on new chikungunya vaccine introduction. Author summary: The first vaccine to prevent chikungunya fever has been recently approved in November 2023 by the US FDA and multiple chikungunya vaccine candidates are in different phases of the development pipeline. These will be the first-ever vaccines against an alphavirus and offer new technologies for vaccine development against other viruses of the same family that may cause future epidemics. We interviewed stakeholders from areas at risk of chikungunya outbreaks across Latin America, Asia and Africa, and identified gaps in Evidence-to-Recommendation criteria that should be addressed alongside vaccine introduction. Our findings show that stakeholders from different regions prioritised chikungunya differently, but all stakeholders agreed that the unknown burden of disease, undefined target populations for vaccination and non-specific disease surveillance were challenges that needed to be addressed imminently. To address these gaps, the involvement of stakeholders in all phases of vaccine development and rollout will be crucial to uncover future challenges and to ensure vaccine equity. [ABSTRACT FROM AUTHOR]

Background Analyses of the global spatial and temporal distribution of enteric fever outbreaks worldwide are important factors to consider in estimating the disease burden of enteric fever disease burden. Methods We conducted a global literature review of enteric fever outbreak data by systematically using multiple databases from 1 January 1990 to 31 December 2018 and classified them by time, place, diagnostic methods, and drug susceptibility, to illustrate outbreak characteristics including spatial and temporal patterns. Results There were 180 940 cases in 303 identified outbreaks caused by infection with Salmonella enterica serovar Typhi (S. Typhi) and Salmonella enterica serovar Paratyphi A or B (S. Paratyphi). The size of outbreak ranged from 1 to 42 564. Fifty-one percent of outbreaks occurred in Asia, 15% in Africa, 14% in Oceania, and the rest in other regions. Forty-six percent of outbreaks specified confirmation by blood culture, and 82 outbreaks reported drug susceptibility, of which 54% had multidrug-resistant pathogens. Paratyphoid outbreaks were less common compared to typhoid (22 vs 281) and more prevalent in Asia than Africa. Risk factors were multifactorial, with contaminated water being the main factor. Conclusions Enteric fever outbreak burden remains high in endemic low- and middle-income countries and, despite its limitations, outbreak data provide valuable contemporary evidence in prioritizing resources, public health policies, and actions. This review highlights geographical locations where urgent attention is needed for enteric fever control and calls for global action to prevent and contain outbreaks. [ABSTRACT FROM AUTHOR]

Background: Typhoid fever remains an important public health problem in developing countries and is endemic in many parts of Asia and Africa where the incidence of disease typically peaks in school-aged children. Age restrictions and other limitations of existing oral live-attenuated typhoid and parenteral Vi polysaccharide vaccines have triggered the development of Vi conjugate vaccines with improved immunological properties, use in younger age range, and longer durability of protection. We present the safety, reactogenicity, and immunogenicity data from a Phase II study after a single dose of Vi polysaccharide conjugated to diphtheria toxoid (Vi-DT) conducted in 6-23-month old Filipino children., Methods: This is a randomized, observer-blinded Phase II study to assess the immunogenicity, safety and reactogenicity of Vi-DT compared to placebo, conducted in Muntinlupa City, The Philippines. Participants aged 6-23 months were enrolled and randomized to Vi-DT (25 µg) or placebo (0.9% sodium chloride) and evaluated for immunogenicity and overall safety 28 days post vaccination., Results: A total of 285 participants were enrolled and age-stratified: 6 to < 9 months, 9-12 months, and 13-23 months. Seventy-six (76) participants received Vi-DT and 19 received placebo per each strata. All participants seroconverted after a single dose of Vi-DT versus 7% of placebo recipients. Anti-Vi IgG GMT was 444.38 [95% CI (400.28; 493.34)] after a single dose of Vi-DT; there was no change in GMT after placebo administration, 0.41 [95% CI (0.33; 0.51), p < 0.0001]. A similar pattern of immunogenicity was reported across all age strata. The vaccine reported to be safe and well tolerated., Conclusions: Vi-DT vaccine was immunogenic, safe, and well tolerated in children aged 6-23 months. ClinicalTrials.gov registration number: NCT03527355., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Conflicts of Interest Maria Rosario Capeding received research grant. Seon-young Yang, Dong Soo Ham, Ji Hwa Ryu, and Hun Kim are employees of SK bioscience. Dr. Jerome Kim has consulted for Takeda and served as an unpaid consultant for GSK. All other authors declare having no conflict of interest., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Enteric fever caused by Salmonella enterica serovar Typhi and Salmonella enterica serovar Paratyphi is still a major disease burden mainly in developing countries. Previously, S. Typhi was believed to be the major cause of enteric fever. The real situation is now becoming clear with reports emerging from many Asian countries of S. Paratyphi, mostly S. Paratyphi A, causing a substantial number of cases of enteric fever. Although there have been advances in the use of the currently available typhoid vaccines and in the development of newer typhoid vaccines, paratyphoid vaccine development is lagging behind. Since the disease caused by S. Typhi and S. Paratyphi are clinically indistinguishable and are commonly termed 'enteric' fever, it will be necessary to have a vaccine available against both S. Typhi and S. Paratyphi A as a bivalent 'enteric fever vaccine'.