ObjectivesWe aimed to develop a systematic synthesis of systematic reviews of health impacts of climate change, by synthesising studies’ characteristics, climate impacts, health outcomes and key findings.DesignWe conducted an overview of systematic reviews of health impacts of climate change. We registered our review in PROSPERO (CRD42019145972). No ethical approval was required since we used secondary data. Additional data are not available.Data sourcesOn 22 June 2019, we searched Medline, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Embase, Cochrane and Web of Science.Eligibility criteriaWe included systematic reviews that explored at least one health impact of climate change.Data extraction and synthesisWe organised systematic reviews according to their key characteristics, including geographical regions, year of publication and authors’ affiliations. We mapped the climate effects and health outcomes being studied and synthesised major findings. We used a modified version of A MeaSurement Tool to Assess systematic Reviews-2 (AMSTAR-2) to assess the quality of studies.ResultsWe included 94 systematic reviews. Most were published after 2015 and approximately one-fifth contained meta-analyses. Reviews synthesised evidence about five categories of climate impacts; the two most common were meteorological and extreme weather events. Reviews covered 10 health outcome categories; the 3 most common were (1) infectious diseases, (2) mortality and (3) respiratory, cardiovascular or neurological outcomes. Most reviews suggested a deleterious impact of climate change on multiple adverse health outcomes, although the majority also called for more research.ConclusionsMost systematic reviews suggest that climate change is associated with worse human health. This study provides a comprehensive higher order summary of research on health impacts of climate change. Study limitations include possible missed relevant reviews, no meta-meta-analyses, and no assessment of overlap. Future research could explore the potential explanations between these associations to propose adaptation and mitigation strategies and could include broader sociopsychological health impacts of climate change.

Background Due to the explosion in rapid reviews in the literature during COVID-19, their utility in universal health coverage and in other routine situations, there is now a need to document and further advance the application of rapid review methods, particularly in low-resource settings where a scarcity of resources may preclude the production of a full systematic review. This is the introductory article for a series of articles to further the discussion of rapid reviews for health policy and systems decision-making. Main body The series of papers builds on a practical guide on the conduct and reporting of rapid reviews that was published in 2019. The first paper provides an evaluation of a rapid review platform that was implemented in four centers in low-resource settings, the second paper presents approaches to tailor the methods for decision-makers through rapid reviews, the third paper focuses on selecting different types of rapid review products, and the fourth pertains to reporting the results from a rapid review. Conclusion Rapid reviews have a great potential to inform universal health coverage and global health security interventions, moving forward, including preparedness and response plans to future pandemics. This series of articles will be useful for both researchers leading rapid reviews, as well as decision-makers using the results from rapid reviews.