Sidy Ndiaye

Dr. Sidy Ndiaye

orcid

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 April 2021 in Vaccine
Verified
Journal Article
Open access
CSChristoph A Steffen
Christoph A Steffen
LHLouise Henaff
Louise Henaff
ADAntoine Durupt
Antoine Durupt
NONathalie El Omeiri
Nathalie El Omeiri
SNSidy Ndiaye
Sidy Ndiaye
JHJoachim Hombach
Joachim Hombach
Countries face an increasingly complex vaccination landscape. As well as ever-changing infectious disease epidemiology, the number and diversity of vaccine-preventable diseases, vaccine products, and vaccine technologies continue to increase. To ensure that vaccination decision-making is transparent, country-owned and informed by sound scientific evidence, many countries have established national immunization technical advisory groups (NITAGs) to provide independent expert advice. The past decade has seen substantial growth in NITAG numbers and functionality, and there is now a need to consolidate this progress, by further capacity building, to ensure that NITAGs are responsive to the changing face of immunization over the next decade.

27 May 2024 in Vaccine
Verified
Journal Article
Open access
EDEliza Dryer
Eliza Dryer
ASAbigail Shefer
Abigail Shefer
SDShalini Desai
Shalini Desai
LRLance Rodewald
Lance Rodewald
MBMagdalena Bastías
Magdalena Bastías
EKErin Kennedy
Erin Kennedy
As dozens of new National Immunization Technical Advisory Groups (NITAGs) were established worldwide in the past decade, and as existing NITAGs continued to play an important role in vaccine policy, global NITAG partners recognized a need for a standardized assessment tool to evaluate and strengthen their functions. This article describes the development of the NITAG Maturity Assessment Tool (NMAT), a stepwise evaluation tool that assesses NITAGs on seven key indicators of structure and process. A draft tool was developed through an iterative, consensus-based process with an expert working group before it was piloted with an economically and geographically diverse convenience sample of NITAGs. The final NMAT is a flexible tool that can be used by in-country or external evaluators to understand NITAG maturity, identify priorities for optimization, and measure the impact of strengthening efforts.

17 January 2025 in Vaccines
Verified
Journal Article
Open access
PDF file
LHLouise Henaff
Louise Henaff
LDLaure Dumolard
Laure Dumolard
VBVinod Kumar BURA
Vinod Kumar BURA
GSGerald Etapelong Sume
Gerald Etapelong Sume
SNSidy Ndiaye
Sidy Ndiaye
CSChristoph A Steffen
Christoph A Steffen
Introduction: Well-functioning National Immunization Technical Advisory Groups (NITAGs) are valuable contributors to decision-making processes in the complex immunization policy arena. This paper describes the progress made globally on the establishment and strengthening of these key advisory groups and discusses some of their strengths, challenges, and opportunities. Methods: The data submitted annually by countries to the World Health Organization (WHO) via the WHO/UNICEF Joint Reporting Form (JRF) were analyzed, comparing the NITAG functionality criteria in 2012 and 2023. Results: In 2023 and 2012, 88% and 61% of countries, respectively, reported having a NITAG. A total of 77% of NITAGs met all six NITAG process criteria in 2023 compared to 33% in 2012. This progress was most notable in the WHO African Region, increasing from 7% (2012) to 77% (2023), and the South-East Asia Region, increasing from 45% (2012) to 91% (2023). In 2023, 84% of NITAGs issued a vaccine-policy recommendation that was adopted by decision-makers. Discussion: Marked progress has been made since 2012 on establishing and maintaining NITAGs, with a small number of countries yet to form an advisory committee. Supporting and sustaining NITAG functions remains an important means for countries to foster independent and transparent expert advice on vaccine and immunization policy. Setbacks in countries facing instability or political turmoil are a reminder of the reversibility of progress. WHO and partners play an important role in supporting countries in strengthening these advisory committees. Continuous commitment by countries to the function and involvement of NITAGs in policy recommendations is essential for enhancing the strength and resilience of immunization programs.


26 April 2026 in Vaccines
Verified
Journal Article
Open access
PDF file
CWCharles Shey Wiysonge
Charles Shey Wiysonge
Abdu AdamuAbdu Adamu
Abdu Adamu
ABAdo Mpia BWAKA
Ado Mpia BWAKA
CWConstance Ning Wiysonge
Constance Ning Wiysonge
JTJohnson M. Ticha
Johnson M. Ticha
BMBalcha Masresha
Balcha Masresha
Background: The end of the COVID-19 public health emergency of international concern (PHEIC) in May 2023 marked a transition from disruption to recovery and rebuilding of health systems. The WHO African Region entered this period with declining routine immunization coverage, widening inequities, and fragile surveillance systems. We conducted a critical narrative synthesis of post-PHEIC recovery and the transformation of immunization systems in the region from 2023 to 2025. Methods: We thematically analyzed publicly available data from the WHO and other sources using a systems-oriented framework covering immunization coverage, equity, vaccine introductions, disease control, governance, financing, and data systems. Results: Regional coverage for most antigens was restored to 2019 pre-pandemic levels by 2024, e.g., three doses of diphtheria-tetanus-pertussis-containing vaccines at 76%. However, progress remains insufficient to meet the Immunization Agenda 2030 (IA2030) target of 90% coverage. In addition, there were 6.7 million zero-dose children in the 2024 birth cohort (6.3% higher than the 6.3 million in 2019), concentrated in a few countries. The IA2030 target is a 50% reduction in the number of zero-dose children by 2030, compared to 2019. Recovery initiatives have restored services, while accelerated introductions (e.g., malaria vaccines introduced in 20 new countries in 2024–2025) signal renewed system momentum. Yet, progress has plateaued at pre-pandemic levels, reflecting structural constraints rather than sustained transformation. Concurrently, recurrent outbreaks of measles, yellow fever, and other vaccine-preventable diseases highlight persistent immunity gaps and surveillance limitations. Structural constraints (including financing fragility, subnational inequities, and system fragmentation) continue to limit sustained progress. Conclusion: This study offers important insights that can inform immunization policymaking in the WHO African Region and beyond. Current post-PHEIC trends reflect recovery without transformation. Achieving IA2030 targets will require a shift from broad coverage expansion to precision delivery approaches that prioritize zero-dose and underserved populations. Immunization must be positioned as a central pillar of primary health care and health security systems.

27 December 2024 in Vaccines
Verified
Journal Article
Open access
PDF file
FMFranck Fortune Mboussou
Franck Fortune Mboussou
CWCharles Shey Wiysonge
Charles Shey Wiysonge
BFBridget Lindsay Farham
Bridget Lindsay Farham
ABAdo Mpia BWAKA
Ado Mpia BWAKA
SWSarah Wanyoike
Sarah Wanyoike
BIBénido Impouma
Bénido Impouma
Background/Objectives: The Addis Declaration on Immunization (ADI) is a historic pledge aiming at increasing political will to achieve universal access to immunization services and includes ten commitments to shape the future of immunization in Africa. Methods: To analyze African countries’ performance in achieving the fourth ADI commitment, a cross-sectional retrospective study was conducted including the 54 African Member States of the World Health Organization (WHO) out of 55 African Union (AU) Member States. The fourth ADI commitment aims at increasing the effectiveness and efficiency of immunization delivery systems and has four performance indicators. Results: The median percentage of districts with less than 10% of dropout rate between the first dose of diphtheria–tetanus–pertussis-containing vaccine (DTP1) and the third dose (DTP3) was 86.5%, ranging from 22% to 100%. Thirty-four countries (63%) recorded 80% or above of districts with less than 10% dropout rate between DTP1 and DTP3. Eleven countries (20.3%) and ten countries (18.5%) sustained 90% or above coverage for DTP3 and first dose of measles-containing vaccine (MCV1), respectively, in the past three years (2021–2023). Four countries (7.4%) had 44.5 skilled health workers per 10,000 people. Out of the 54 WHO Member States, 7 achieved at least three of the four indicators of the fourth ADI commitment (13%). Conclusions: It is critical, as a follow up to this study, to document best practices from the seven countries that achieved the fourth ADI commitment. Additionally, a deeper analysis of factors associated with achieving the ADI commitments is required.