Preventing Childhood Hearing Loss Through Vaccination: An Underestimated Public Health Opportunity

Background: Infectious diseases remain a major preventable cause of childhood hearing loss. Although the protective effects of certain vaccines, such as those for rubella and meningitis, are well established, a striking paradox exists in global research: over the last 40 years, only nine studies have rigorously evaluated the impact of vaccination on hearing loss. Furthermore, all of these studies originate from high-income countries and cover only three pathogens. This leaves a catastrophic lack of evidence for low- and middle-income countries (LMICs), where approximately 90% of children with hearing loss live. Methods: To address this gap, this narrative review synthesizes evidence primarily drawn from a recent comprehensive scoping review linking 26 vaccine-preventable or potentially preventable deafness-causing infections to 19 vaccines. Rather than repeating established findings, we focus on integrating molecular mechanisms, stratifying direct versus indirect clinical evidence, and translating these insights into an actionable research agenda for LMICs. Results: We also systematically synthesize the molecular mechanisms of pathogen-induced hearing loss, evaluate the direct and indirect clinical evidence, and analyze the recent setback of the 2025 mRNA-1647 Phase III trial to understand the challenges in CMV vaccine development. We propose a targeted, actionable research agenda for LMICs emphasizing the integration of standardized audiological endpoints into future vaccine trials and post-marketing surveillance. Conclusions: The central argument of this review is that the field currently rests on a dangerously thin empirical base. We call for strategic LMIC-led investments and multisectoral collaboration to transform the vast preventive potential of vaccination into tangible global public health benefits.