Background: In 2015 several countries reported a potentially novel association between Zika virus infection during pregnancy and birth complications. The World Health Organization (WHO) issued emergency guidelines in response to this public health emergency of international concern.

Objectives: To describe and assess the quality of guidelines issued by WHO in response to the 2015-16 Zika virus outbreak.

Methods: We included all guidelines issued by WHO in response to the 2015-16 Zika virus outbreak. We extracted data on their characteristics, evaluated the development, publication and updating processes, and assessed quality using AGREE-II.

Results: 21 guidelines were identified (Table 1). All met WHO publication requirements, including a logo, reference number, disclaimer, issue date and contact information. 81% included an expiration date. 8 updates were issued and in one case the outdated version was still publically available. Translations into languages other than English occurred for 66%, but only 3 of the 8 updates were translated, resulting in translations being available for only 7 of the 13 (56%) most current version of the guidelines. Although external experts were involved in 86% of guidelines, they were not always listed or declarations of interest collected. The funder was listed in only 19%. Only 6/21 referenced a systematic or rapid evidence review: all of which were updates. 25% used a structured approach to formulate recommendations; 29% were peer reviewed; and 33% were reviewed by the WHO Guidelines Review Committee (GRC) Secretariat. AGREE-II scores varied and were lowest for rigor of development, applicability, and editorial independence.

Conclusions: All guidelines met WHO publication standards. A significant number were translated into languages other than English, however, updated versions are not consistently translated. There is room for improvement in the use of research evidence, presentation of declarations of interest, and input from the GRC Secretariat. These data inform future efforts to improve the reporting and trustworthiness of WHO guidelines in the context of a public-health emergencies.