**1. Introduction**

Despite tremendous immunization progress in recent decades, global inequities persist, reflected in the 25 million underimmunized and 18 million zero-dose children in 2021 [1]. Zero-dose children are defined by the Immunisation Agenda 2030 consortium (IA2030) as those that lack access to or are never reached by routine immunization services, measured by the lack of the first dose of diphtheria-tetanus-pertussis containing vaccine (DTP1) [2]. Health inequities are significant drivers of the gaps in immunization coverage and challenges in reaching the most under-served communities in low- and middle-income countries (LMICs) [3,4]. It is estimated that half of zero-dose children reside in three key geographic contexts: urban poor areas, remote communities and conflict-affected settings [5]. Moreover, gender-related barriers to immunization create additional challenges, with indicators such as maternal education and age being significant determinants of immunization coverage [3,4,6,7].

**Citation:** Ivanova, V.; Shahabuddin, A.S.M.; Sharkey, A.; Johri, M. Advancing Immunization Coverage and Equity: A Structured Synthesis of Pro-Equity Strategies in 61 Gavi-Supported Countries. *Vaccines* **2023**, *11*, 191. https://doi.org/ 10.3390/vaccines11010191

Academic Editor: Pedro Plans-Rubió

Received: 19 December 2022 Revised: 11 January 2023 Accepted: 11 January 2023 Published: 16 January 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

To improve immunization coverage and equity, the World Health Organization has launched the Immunization Agenda 2030 (IA2030), with the goal of "leaving no one behind", including a core objective to extend immunization services to reach zero-dose and underimmunized children and communities [8]. Aligned with IA2030, Gavi has launched its 5.0 Strategy with the goal of reducing the number of zero-dose children by 25% by 2025 and by 50% by 2030 [9,10]. Through several funding streams, Gavi supports immunization programs in more than 70 LMICs [11]. Gavi also supports UNICEF to conduct implementation research to improve policies and programs, identify implementation bottlenecks and promote equity in immunization delivery [12].

To understand how countries are currently addressing these gaps and where there is scope for improvement, we undertook a mapping and structured synthesis of proequity strategies for immunization across 61 low-income countries receiving programmatic support from Gavi, expanding on a more targeted mapping exercise by Dadari and colleagues [13]. The synthesis aimed to identify current practices and promising opportunities to reach zero-dose and underimmunized children in LMICs and to inform the creation of a searchable database to enable countries to identify potential solutions to immunization challenges and support country-level programmatic planning.
