To answer the question, What are the best ways to communicate uncertainties to public audiences, at-risk communities, and stakeholders
during public health emergency events? we conducted a systematic review of published studies, grey literature, and media reports
in English and other United Nations (UN) languages Arabic, Chinese, French, Russian, and Spanish. Almost 2900 English
and 8600 other UN languages titles and abstracts were scanned of which 33 English and 13 other UN languages data-based
primary studies were selected, which were classified into four methodological streams: Quantitative-comparison groups;
Quantitative-descriptive survey; Qualitative; and Mixed-method and case-study. Study characteristics (study method,
country, emergency type, emergency phase, at-risk population) and study findings (in narrative form) were extracted from
individual studies. The findings were synthesized within methodological streams and evaluated for certainty and confidence.
These within-method findings were next synthesized across methodological streams to develop an overarching synthesis
of findings. The findings showed that country coverage focused on high and middle-income countries in Asia, Europe,
North America, and Oceania, and the event most covered was infectious disease followed by flood and earthquake. The
findings also showed that uncertainty in public health emergency events is a multi-faceted concept with multiple components.
There is universal agreement, with some exceptions, that communication to the public should include explicit information
about event uncertainties, and this information must be consistent and presented in an easy to understand format. Additionally,
uncertainty related to events requires a distinction between uncertainty information and uncertainty experience. At-risk
populations experience event uncertainty in lives full of uncertainties from other sources. Event uncertainty is experienced
and uncertainty information may be understood and misunderstood in the same general ways by the public, experts, and
policy makers. Experience of event uncertainty may be a defining feature for media professionals as well due to contradictory
and inconsistent information in the environment.