Background: In 2004, global guidelines for the management of acute diarrhoea were amended to include the recommendation that children receive zinc supplementation for 10-14 days, in addition to Oral Rehydration Salts (ORS) and continued feeding. In the decade since these guidelines were issued, and nearly 4 decades following the introduction of ORS, ORS is used in 41% of diarrheal episodes, while zinc is used in only 5%.

Objectives: We conducted a systematic review to synthesise available evidence on zinc introduction at scale and improve understanding of the relationship between programmatic inputs and health outcomes and impact as a result of zinc introduction in low-resource settings.

Methods: We searched for articles published from 2004 to April 2015 in over two dozen databases and grey literature. Unique programmes were identified and categorised according to geographic setting and scale. Articles describing programmes implemented to a population of ≥100,000 were assessed qualitatively to understand the relationship between global level factors, programmatic inputs and health outcomes and impact as a result of zinc introduction.

Results: Twenty-one countries were reported to implement zinc at scale, through 28 unique programmes identified from full-text articles (n=39), reports (n=11), and abstracts (n=9). Where zinc coverage exceeded 60% under effectiveness trial conditions, the mean coverage attained was 18% for all other programmes. Studies with higher coverage were implemented to fewer beneficiaries; observed to employ community-based delivery strategies; provide zinc of free of charge to patients; and included elements of behaviour-change communication directed to both providers and caregivers alike. Additional factors including global level initiatives; public-private sector engagement; standalone vs. implementation as part of broader initiatives; product; as well as monitoring and evaluation activities are reviewed.
Conclusions: Lack of support for diarrhoea treatment in the last decade has compromised efforts to scale up. More robust research is needed to understand the factors associated with higher coverage for zinc and ORS at scale.