Hepatitis A GBM strain (adsorbed) / Typhoid polysaccharide vaccine suspension for injection 1ml pre-filled syringes

Background/Objectives: Over the past 50 years, developing new vaccines has been pivotal in responding to emerging and re-emerging diseases globally. However, despite substantial partner support, introducing new vaccines in sub-Saharan Africa remains challenging. This systematic review documents the barriers to new vaccine introduction in sub-Saharan Africa by distinguishing between vaccines integrated into routine immunization programs and those introduced primarily for outbreak response. Methods: A comprehensive electronic search was conducted across five databases for articles published in English or French on the challenges of new vaccine introduction in sub-Saharan Africa. Three reviewers screened articles independently based on the titles and abstracts, with full-text assessments conducted for inclusion. Data were analyzed thematically and synthesized narratively. Results: A total of 796 articles were retrieved from the five databases. Following the screening, 33 articles were finally retained and included in the review. These articles concerned the introduction of eight new vaccines (malaria vaccine, COVID-19 vaccine, HPV vaccine, Ebola vaccine, cholera vaccine, hepatitis B vaccine, rotavirus vaccine, and typhoid vaccine). The analyses revealed coordination and financing challenges for six vaccines in seventeen countries, acceptability challenges for five vaccines in ten countries, logistical challenges for two vaccines in six countries, and quality service delivery challenges for three vaccines in thirteen countries. Conclusions: Addressing the challenges of introducing new vaccines in sub-Saharan Africa requires targeted, evidence-based strategies. Prioritizing political commitment, innovative funding, public education, workforce development, and infrastructure improvements will strengthen immunization systems and enable timely vaccine delivery. Collaborative efforts and a focus on local context can advance equitable health outcomes, safeguard public health, and support global immunization goals.

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BackgroundImmunization is a highly effective intervention for controlling over 20 life-threatening infectious diseases, significantly reducing both morbidity and mortality rates. One notable achievement in vaccination efforts was the global eradication of smallpox, which the World Health Assembly declared on 8 May 1980. Additionally, there has been a remarkable 99.9% reduction in wild poliovirus cases since 1988, decreasing from more than 350,000 cases that year to just 30 cases in 2022.ObjectivesThe objective of this review was to assess the effects of various interventions designed to increase vaccination uptake among adults.Search methodsA thorough search was conducted in the CENTRAL, Embase Ovid, Medline Ovid, PubMed, Web of Science, and Global Index Medicus databases for primary studies. This search was conducted in August 2021 and updated in November 2024.Selection criteriaRandomized trials were eligible for inclusion in this review, regardless of publication status or language.Data analysisTwo authors independently screened the search outputs to select potentially eligible studies. Risk ratios (RR) with 95% confidence intervals (CI) were calculated for each randomized controlled trial (RCT). A meta-analysis was conducted using a random-effects model, and the quality of the evidence was assessed using the GRADE approach.Main resultsA total of 35 randomized controlled trials met the inclusion criteria and were included in this review, with the majority conducted in the United States. The interventions targeted adults aged 18 and older who were eligible for vaccination, involving a total of 403,709 participants. The overall pooled results for interventions aimed at increasing influenza vaccination showed a risk ratio of 1.41 (95% CI: 1.15, 1.73). Most studies focused on influenza vaccination (18 studies), while the remaining studies examined various other vaccines, including those for hepatitis A, COVID-19, hepatitis B, pneumococcal disease, tetanus, diphtheria, pertussis (Tdap), herpes zoster, and human papillomavirus (HPV). The results indicate that letter reminders were slightly effective in increasing influenza vaccination uptake compared to the control group (RR: 1.75, 95% CI: 0.97, 1.16; 6 studies; 161,495 participants; low-certainty evidence). Additionally, participants who received education interventions showed increased levels of influenza vaccination uptake compared to those in the control group (RR: 1.88, 95% CI: 0.61, 5.76; 3 studies; 1318 participants; low-certainty evidence). Furthermore, tracking and outreach interventions also led to an increase in influenza vaccination uptake (RR: 1.87, 95% CI: 0.78, 4.46; 2 studies; 33,752 participants; low-certainty evidence).ConclusionsLetter reminders and educational interventions targeted at recipients are effective in increasing vaccination uptake compared to control groups.

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Co-administration of multiple vaccines during a single clinical visit is common in pediatric immunization programs, but administering three or more injections simultaneously has raised safety concerns. This systematic review, conducted in 2023, assessed the safety of administering three or more vaccines at the same time compared with giving fewer or the same vaccines across separate sessions. Data from 26 studies were analyzed using random-effects meta-analyses. The risk of any adverse event (AE) was modestly increased (OR ≈ 1.54), mainly due to expected and transient reactions such as fever, irritability and injection-site pain. Importantly, there was no significant increase in serious adverse events (SAEs) (OR 1.07, 95% CI 0.92-1.25). Differences in systemic (OR 1.19, 95% CI 0.95-1.50) or local AEs (OR 1.37, 95% CI 0.85-2.22) were not statistically significant. These findings support the continued co-administration of multiple vaccines in pediatric programs, providing a nuanced safety profile for policymakers and clinicians.

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Background: Residual blood specimens offer a cost- and time-efficient alternative for conducting serological surveys. However, their use is often criticized due to potential issues with the representativeness of the target population and/or limited availability of associated metadata. We conducted a scoping review to examine where, when, how, and why residual blood specimens have been used in serological surveys for vaccine-preventable diseases (VPDs) and how potential selection biases are addressed. Methods: The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines and identified relevant papers published in 1990-2022. Results: A total of 601 articles met the inclusion criteria after title, abstract screening, and full-text review. The most studied VPDs using residual blood specimens were COVID-19 (27%), hepatitis E (16%), hepatitis B (10%), influenza (9%), HPV (7%), and measles (7%). Residual blood specimens were primarily sourced from diagnostic specimens (61%) or blood and plasma donations (37%). Almost all articles used specimens linked to basic demographic data (e.g., age and sex), with 47% having access to extended demographic data (e.g., geographic location). Common strategies to address potential biases included comparing results with published estimates (78%) and performing stratified analyses (71%). Conclusions: Residual blood specimens are widely used in seroprevalence studies, particularly during emerging disease outbreaks when rapid estimates are critical. However, this review highlighted inconsistencies in how researchers analyze and report the use of residual specimens. We propose a set of recommendations to improve the analysis, reporting, and ethical considerations of serological surveys using residual specimens.

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BackgroundIndia is one of the countries with a high typhoid fever burden. In 2022, the National Technical Advisory Group on Immunisation recommended including the typhoid conjugate vaccine (TCV) in the Universal Immunisation Programme. In this study, we aimed to estimate the 2023 burden of typhoid fever and its antimicrobial resistance (AMR) to inform targeted vaccine introduction strategies.MethodsWe used a decision tree model to estimate typhoid cases, hospitalisations, complications, and deaths. Incidence and clinical parameters were derived from a multicentre Indian study, with state-wise AMR prevalence from a systematic review. Two co-primary and four alternative scenarios were presented to validate the robustness of the findings.FindingsWe estimated 4.9 million (95% UI: 4.4-5.6) typhoid cases and 7850 (4300-14,900) deaths in India in 2023. Of 730,000 (534,000-970,000) hospitalisations, 600,000 (435,000-799,000; 82%) were attributable to fluoroquinolone-resistant. Under primary scenario A, children InterpretationFluoroquinolone-resistance drives a large share of typhoid-related hospitalisations and deaths, especially in children under five and in high-burden states of India. Targeted TCV introduction, with broader age coverage among children, would maximise impact.FundingWISE programme; Vaccine Impact Modelling Consortium; Japan Agency for Medical Research and Development.

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Ocular adverse events following COVID-19 vaccination are well described; however, systematic analyses of non-COVID antiviral vaccines remain limited. This review aimed to evaluate ocular complications associated with non-COVID antiviral immunizations, including influenza, varicella-zoster (VZV), human papillomavirus (HPV), and hepatitis B (HBV) vaccines. A systematic search (PROSPERO CRD4202450873) identified 122 patients (184 eyes) from 8,487 publications, including case reports, case series, and observational studies. Uveitis was the most common (92/184 eyes; 50.0%, 95% CI 42.8%-57.2%), frequently following influenza vaccination (35/122; 28.7%, 95% CI 20.7%-36.7%). Most patients (95/122; 77.9%, 95% CI 70.5%-85.3%) required systemic corticosteroids, reflecting predominant inflammation. Ocular symptoms occurred within 30 days in 84.4% (103/122)of cases, with peak onset at 7-30 days (62/122; 50.8%, 95% CI 42.0%-59.6%). Despite appropriate treatment, 18 patients (20.0%, 95% CI 13.0%-29.4%) experienced persistent inflammation or required therapy beyond 1 month, categorized as "long-vax", defined as ocular symptoms persisting for ≥ 4 weeks after vaccination. Although rare, antiviral vaccine-associated ocular complications may persist, posing a risk of long-term visual morbidity and emphasizing the importance of clinician awareness, postvaccination surveillance, and counseling for patients receiving repeated or combined vaccine exposures.

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The mucosal system, which includes the respiratory, gastrointestinal, and urogenital tracts, serves as a primary entry point for pathogens, with a unique immune microenvironment and specialized defense mechanisms. In recent years, especially following the onset of the COVID-19 pandemic, there has been increasing recognition of the importance of mucosal immunity, motivated by an enhanced comprehension of its fundamental mechanisms. Currently, strategies based on mucosal delivery systems to administer antigens and induce strong mucosal protective immunity have become a key focus in the development of mucosal vaccines. Compared with conventional intramuscular delivery, mucosal vaccination can simultaneously elicit a robust local mucosal response, effectively block pathogen entry into the local mucosa, and generate systemic immune responses to prevent symptomatic infections and severe disease. In addition, mucosal delivery offers advantages such as ease of administration and low invasiveness, making it a more widely acceptable approach to vaccination. In the present study, we conducted a systematic review of the mechanisms of mucosal immunity, the technological platforms for mucosal vaccines, and proposed a perspective on the challenges and future directions for the development of next-generation mucosal vaccines, with the goal of enhancing public knowledge and awareness regarding mucosal immunity and its possible effects on global health.

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Viral hepatitis constitutes a substantial global public health challenge. The etiological agents, referred to as hepatitis viruses, are primarily categorized into five types: hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV), and hepatitis E virus (HEV). Among the various preventive strategies, vaccination is widely acknowledged as the most cost-effective and efficient method for controlling viral hepatitis and its related hepatic complications. To date, numerous countries have initiated extensive vaccination programs targeting hepatitis A and hepatitis B. Advances in biotechnology have facilitated substantial progress in vaccine formulation design, the development of innovative adjuvants, and the utilization of novel vectors. However, significant challenges persist, including inadequate vaccination coverage, inconsistent immune responses among vulnerable populations, and concerns regarding vaccine safety. This article presents a systematic review of recent advancements, the current status of vaccination efforts, and ongoing challenges associated with hepatitis vaccines, with the objective of providing critical insights to support the World Health Organization's goal of eliminating viral hepatitis as a public health threat by 2030.

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BackgroundFlooding from natural disasters has become increasingly common worldwide, increasing the risk of infectious disease transmission, particularly waterborne and vector-borne infections. Although many studies report outbreaks following floods, the evidence remains fragmented across regions and pathogens. A comprehensive review is needed to clarify these associations and inform effective prevention and response strategies.MethodsA systematic search of PubMed, Embase, and the Cochrane Library was conducted between November 2024 and January 2025, identifying studies published from January 1, 2014, to December 31, 2024. Eligible studies assessed the association between flooding and waterborne or vector-borne infections and their health outcomes or evaluated related prevention and response interventions. Data were synthesized narratively due to study heterogeneity.ResultsOf the 1,785 records identified, 71 studies met the inclusion criteria. Flooding was consistently associated with increased incidence of waterborne infections, including leptospirosis, cholera, bacillary dysentery, and hepatitis A/E, as well as vector-borne infections such as dengue and malaria. Outbreaks varied by region, flood characteristics, and the strength of existing public health infrastructure. The lag period between the onset of flooding and disease emergence ranged from days to weeks. Timely interventions such as chemoprophylaxis, vaccination, water, sanitation, and hygiene (WASH) measures, and vector control may help mitigate outbreaks; however, most included studies were observational in design, and the overall certainty of evidence was low to moderate. Data on health system impacts, including hospitalization rates, intensive care unit burden, and mortality stratified by level of care, remain limited.ConclusionFlooding was most frequently associated with increased incidence of cholera, bacillary dysentery, leptospirosis, dengue, and malaria, each with distinct lag periods critical for outbreak prediction. Reported lag periods ranged from days to weeks. Limited observational evidence suggests that doxycycline chemoprophylaxis for leptospirosis, oral cholera vaccination, and early vector control may be useful in selected post-flood settings. These findings support strengthened post-flood surveillance and context-specific preparedness measures, while highlighting the need for higher-quality comparative studies.RegistrationPROSPERO CRD42025635687.Clinical trial numbeNot applicable.

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BackgroundFunctional active safety surveillance is essential for post-authorization assessment and life-cycle safety evidence generation of vaccines and medicines. Data collected through active surveillance methods are routinely used for post-approval surveillance of novel vaccines and medicines. Implementing these methods in low- and middle-income countries remains challenging.ObjectiveThis systematic review identified and assessed existing active safety surveillance in low- and middle-income countries, including key features, strengths, and limitations.MethodsA search of EMBASE and PubMed Google Scholar databases was conducted. The protocol was registered with PROSPERO and adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. Findings were synthesized narratively and categorized by surveillance systems characteristics.ResultsOf 13,027 records identified, 423 publications met inclusion criteria. Articles spanned 96 low- and middle-income countries, with India (96), China (57), Brazil (30), Iran (26), Ethiopia (21), Indonesia (20), Uganda (18), Kenya (17), and Ghana (16), most represented. The majority focused on vaccines (211). A total of 127 articles utilized mobile technologies for follow-up, online data collection, and/or adverse event reporting. Fifteen percent of vaccine surveillance systems described in articles demonstrated flexibility to incorporate new vaccines, 34% reported multi-sectoral collaborations, and 10% involved multiple countries. Gaps identified include small sample sizes, lack of sustainability, limited flexible surveillance, staffing challenges, and limited use of standard case definitions and digital technologies.ConclusionsActive safety surveillance in low- and middle-income countries has made progress but still faces challenges. The capture and management of safety data through harmonized digital tools that promote consistency in recording and reporting and cross-country collaborations are crucial in further strengthening active safety surveillance in low- and middle-income countries.

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