Our aim was to summarize and compare relevant recommendations from evidence-based CPGs (EB-CPGs).Systematic review of clinical practice guidelines. Data sources: PubMed, EMBase, Cochrane Library, LILACS, Tripdatabase, and additional sources. In July 2017, we searched CPGs that were published in the last 10 years, without language restrictions, in electronic databases, and also searched specific CPG sources, reference lists, and consulted experts. Pairs of independent reviewers selected EB-CPGs and rated their methodological quality using the AGREE-II instrument. We summarized recommendations, its supporting evidence, and strength of recommendations according to the GRADE methodology.We included 16 EB-CPGs out of 2262 references identified. Only nine of them had searches within the last 5 years and seven used GRADE. The median (percentile 25–75) AGREE-II scores for rigor of development was 49% (35–76%) and the domain “applicability” obtained the worst score 16% (9–31%). We summarized 31 risk stratification recommendations, 21.6% of which were supported by high/moderate quality of evidence (41% of them were strong recommendations), and 16 therapeutic/preventive recommendations, 59% of which were supported by high/moderate quality of evidence (75.7% strong). We found inconsistency in ratings of evidence level. “Guidelines’ applicability” and “monitoring” were the most deficient domains. Only half of the EB-CPGs were updated in the past 5 years.We present many strong recommendations that are ready to be considered for implementation as well as others to be interrupted, and we reveal opportunities to improve guidelines’ quality. We identified many risk stratification and therapeutic strong recommendations that can be implemented and other ones usually followed by many anesthesiologists in their daily practice that should be interrupted.Finally, we described opportunities to improve guidelines’ quality.An estimated 313 million major surgical procedures are undertaken every year worldwide . HoweverMultiple medical societies and organizations around the world have published preoperative evaluation CPGs; however, many of them are not even based on solid scientific evidence. Additionally, not all of them harness methods like the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, which is one of the soundest system for rating the quality of a body of evidence in systematic reviews and CPGs . GRADE oA systematic review found no evidence from high quality studies to support routine preoperative tests in healthy adults undergoing non-cardiac surgery . Risk stFor this reason, through an overview of clinical practice guidelines, we aimed to identify and synthetize EB-CPGs on preoperative care that were published worldwide in the last 10 years, in order to help prioritization processes. We also rated CPGs’ quality and summarized recommendations describing their level of evidence and the strength of recommendations according to the GRADE approach .We performed a systematic review (overview) of EB-CPGs following Cochrane methods  and the 1CPGs of perioperative care published in the last 10 years including those recommendations potentially applicable to any kind of surgery, not site or condition-specificb) Provides a list of the CPG development panel members including their expertise or qualifications.Use standard methods such as Cochrane methods, Equator Network-proposed checklists, or any sufficiently detailed method allowing reproducibility of the identification, data collection, and study risk of bias assessment.Report of the level of evidence that supports each recommendationWe aimed to identify the most reliable CPGs; therefore, we used a definition for EB-CPGs previously reported . The incGuidelines limited to single specific conditions such as obesity, renal disorders, or pheochromocytomaGuidelines limited to single specific body part surgeries such as neurosurgery or colorectal surgery.Guidelines including some recommendations but whose entire focus was clearly not the preoperative careExclusion criteria (any criterion required) were as follows:In July 2017, we searched CPGs published in the last 10 years without language limitations in main electronic databases, metasearch engines, specific CPG sources, reference lists and consultation of experts, and the main scientific societies related to preoperative evaluation. The sources included PubMed, EMBase, Cochrane Library, LILACS, Tripdatabase, and additional sources: National Guideline Clearinghouse, NeLH Guidelines Finder, Guía Salud GPCs en España, GAC guidelines, CMA Infobase: Clinical Practice Guidelines Database (CPGs), New Zealand Guidelines, Scottish Clinical Guidelines, EBM Guidelines, Health Services/Technology Assessment Text (HSTAT), National Institute for Health and Clinical Excellence (NICE), and Institute for Clinical Systems Improvement (ICSI). See Pair of reviewers independently selected  the articles retrieved, with a specific software to facilitate the initial phases of systematic reviews called Early Review Organizing Software (EROS) . One revIndependent pairs of reviewers rated each EB-CPGs using the AGREE-II tool consisting of 23 key items organized in six domains: scope and purpose, stakeholder involvement, rigor of development, clarity of presentation, applicability, editorial independence, and two overall evaluation items . Each itStrongly recommended (++), CPG whose standardized score exceeds 60% in ≥ 4 AGREE-II domains. The scores of the remaining domains must be ≥ 30% and > 60% for the domain rigor of development.Recommended (+), CPG whose standardized score ranges from 30 to 60% in ≥ 4 AGREE-II domains. The rigor of development score must be between 30 and 60%.Not recommended (–), CPG whose standardized score is < 30% in ≥ 4 AGREE-II domains or if rigor of development score is less than 30%.We also categorized each EB-CPGs according to the extent to which they successfully addressed AGREE-II criteria as follows :StronglYes (Y)–no (N) to doing it: ≥ 2/3 recommendations in the same direction (for/against) and ≥ 2/3 strong recommendations.Probably yes (PY)–probably no (PN) to doing it: ≥ 2/3 recommendations in the same direction (for/against) and < 2/3 strong recommendations.Uncertainty (?) to do it: < 2/3 recommendations in the same direction (for/against).To deal with discrepancies between the direction and strength of the CPG recommendations, we applied a rule to decide “doing or not doing the recommendation”:We conducted a tabular synthesis of the recommendations to describe their strength and the level of evidence supporting them according to the current GRADE methodology , and traThe search strategy identified 2262 references after the elimination of duplicates. After the selection process, we identified 23 references corresponding to 16 EB-CPGs published in the last 10 years , SIGN  (2 EB-CPWe presented the scores as a percentage per each AGREE-II domain. The domains with the best median score (percentile 25–75) were editorial independence 91% (81–100), clarity of presentation 85% (69–97), and scope and objective 80% (65–89). Stakeholder involvement 53% (44–62) and rigor of development 49% (35–76) had an intermediate performance while “applicability” was the most deficient 16% (9–31). Regarding the guideline recommendation category, 6/16 (37%) were classified as highly recommended and the rest as recommended (Table We found discrepancies among EB-CPG in 10 out of 102 (10%) risk stratification recommendations After applying the rule “doing or not doing the recommendation,” 31 (60 specific) are “doing” and 31 are (39 specific) “not doing” diagnostic evaluations (see Table We found discrepancies among EB-CPG in 3 out of 78 (4%) of the therapeutic/preventive care recommendations. After applying the direction and strength of recommendations rule to decide doing or not doing the CPG, 15 (55 specific) recommended and 10 (23 specific) did not recommended therapeutic/preventive interventions . It is not surprising because cross-sectional or cohort studies can provide high-quality evidence for test accuracy but indirect evidence for patient-important outcomes. Furthermore, highs level of heterogeneity is almost the rule in risk stratifications test, downgrading even more the level of evidence because of inconsistency –44.The strength of a recommendation is defined as the extent to which one can be confident that the desirable effects of an intervention outweigh its undesirable ones. We found only 12/53 (23%) “strong” risk stratification recommendations statements (for and against) based on high/moderate level of evidence and 43/78 (55%) for therapeutic/preventive care recommendation. Although it would be desirable that higher proportions of high-quality supporting evidence guide panel must consider additional factors. In order to assess competing management alternatives, GRADE proposes to consider four domains: estimates of effect for desirable and undesirable outcomes, confidence in the estimates of effect, values and preferences, and resource use. Guideline panels must integrate these factors to make a strong or weak recommendation for or against an intervention .After our search date, the updated guideline from the European Society of Anesthesiology (ESA) was published, using GRADE and searching until May 2016 . This CPAs described, RCTs are still few and therefore many preoperative interventions rely to a large extent on expert opinion, which in turn requires to be adapted to the reality of nations’ healthcare systems. This large evidence gap should be addressed by related researchers in order to improve the certainty in evidence-based recommendations.Studies on prognostic or diagnostic accuracy tests, including scoring of severity of illness, usually provide low quality of evidence, even when scores such as ASA-PS, RCRI, NSQIP-MICA, POSSUM, and others have been extensively validated .Our updated overview of EB-CPGs, conducted under the rigorous Cochrane methods, may be a useful resource for the professionals involved in preoperative care to consult during decision-making. We present many strong recommendations with sufficient evidence to be routinely implemented in clinical practice. However, any decision should be taken considering local contextual factors.In addition, cost reductions were identified at the clinical level as well as at the health system level in another study –12, 47. Recommendations can be adopted, modified, or even not implemented, depending on institutional or national requirements and legislation and local availability of devices, drugs, and resources . DecisioOur study will be useful for future preoperative care guideline developers or adapters. Consistently with other overviews of clinical guidelines, the domain that received the lowest mean score was the “applicability” domain of the AGREE-II tool. Similarly, the heterogeneity of evidence and the strength of recommendation grading systems in this overview echo that of other clinical guideline overviews –57. Low Guideline developers should ensure rigorous methodological processes and should also make recommendations that are formulated and disseminated in ways that facilitate understanding and application by end-users. For example, the DECIDE Collaboration conducted research and developed tools to improve implementation of evidence-based recommendations by different target audiences, including providers, policy makers, and the public . In thatOur overview identified several controversies, evidence gaps, and issues regarding preoperative care guidelines that warrant future research and reveal opportunities to improve the guidelines quality.).For example, we found many discrepancies about risk stratification recommendations like electrocardiography and chest X-ray, polysomnography, assessment of left ventricular function, stress testing, and coronary angiography in certain populations. We found less discrepancies for therapeutic/preventive care mainly because antimicrobial prophylaxis use beta-blockers (find these discrepancies in the From the perspective of the anesthesiologist practice, there still remain many unanswered questions. For example, in the patient with significant medical, surgical, or obstetrical history, it would be useful to understand how early the pre-anesthetic evaluation should be performed, considering the time required to optimize the patient’s status. There are also uncertainties for the recommendation of fasting for solids in adults and children since many factors can delay gastric emptying, and no fixed rules apply. Fasting should be individualized in some patients and depend on the characteristics of the fat intake. Regarding prokinetics and antacids, patients’ comorbidities like esophageal pathology, bariatric surgery history, or obesity should be considered in the decision, but there is no formal recommendation. In the same way, suspending or not suspending aspirin should be evaluated according to the patient’s history and risk of bleeding of the surgery that could be catastrophic in neurosurgery, spinal surgery, or ophthalmologic surgery. It is also strange that informed consent only has a “weak for,” recommendation from a unique CPGs since there is enough background of litigation due to the lack of consent.We encourage guideline developers to adopt GRADE and AGREE-II tools to elaborate future sound preoperative care guidelines , 22.The huge amount of resources involving preoperative care warrants high-quality nationwide EB-CPGs supported by all relevant stakeholders to improve the chances of a successful implementation. This probably includes the involvement of the Ministry of Health, scientific societies, and consumers working together through a formal process of implementation and monitoring , 59.Although standardization of preoperative care may be desirable, differences in recommendations could reflect differences in contextual factors such as organizational or financial arrangements, legal framework, varied values and preferences, and the acceptability and feasibility of using different interventions. Research exploring reasons for conflicting recommendations in different countries or settings could also drive overall improvements in guideline quality. The key findings are described in Table In conclusion we found significant heterogeneity of guidelines’ quality and rating systems, as well as deficiencies in several guideline quality domains, which reveal opportunities for quality improvement which deserve careful consideration by future guideline developers. Nevertheless, we present many strong recommendations ready to be at present considered for implementation or discontinuation.Additional file 1. Online Only Supplemental Material.


People who inject drugs are at increased health risk in a pandemic due to their greater susceptibility to severe disease and as a consequence of the restrictions put in place to halt the spread of infection. Harm reduction (HR) services, which aim to reduce the negative effects of drug use on health, are likely to be diminished in a pandemic. However, innovative HR interventions and messaging may also develop in response to such a crisis. It is vital to understand the most effective ways to deliver HR in pandemic situations so that guidance can be provided for current and future disruptions to service provision.A rapid evidence review was conducted with the aim of exploring what HR interventions and messaging are most effective during a pandemic-type situation. Ten health databases were systematically searched using terms relevant to the research aim. A search was also made of grey literature, including a targeted search of HR messaging from key national and service provider websites.In the initial search, 121 pieces of evidence were identified which, after screening and de-duplication, resulted in 60 for inclusion. The included evidence consists mainly of non-peer reviewed, pre-publication or expert opinion pieces. The rapid findings suggest that HR services should be deemed essential during a pandemic, with staff supported to work safely and social distancing adaptations implemented. Services should be encouraged to operate more flexibly; for instance, in deciding the amounts of take-home supplies of injecting equipment and medications. The evidence on HR communication was very limited but key messages on infection control, uncertain drug supply and accessing services were identified.This rapid evidence review identifies implications for national policy makers, commissioners and HR service providers. A person-centred rather than disease-centred approach to HR delivered by collaborating partners, as well as prioritizing tailored HR messaging, is recommended. Further research evaluating the delivery of HR services and messaging, particularly focusing on health inequalities, is urgently needed. A novel coronavirus, severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19), was isolated in December 2019 and declared as a global pandemic by the World Health Organization (WHO) in March 2020 [Harm reduction (HR) can be defined as a public health approach which prioritizes reducing the negative effects of drug use rather than eliminating it or attaining abstinence . HR inteDuring the COVID-19 pandemic, many HR services were reduced or suspended completely in order to redeploy staff or facilitate the social distancing required to curb the spread of infection. However, in some areas innovative HR interventions and messaging were developed in response to the crisis. The impact of the pandemic, and these associated service changes, on PWID is not yet known but it is likely that there will have been a worsening of outcomes , 4, 5. TThis report presents preliminary findings from a rapid review of the available evidence (up until 14/08/2020). The aim of the review was to identify which HR interventions and messages for PWID are most effective during situations such as a global pandemic.This rapid evidence review was undertaken at speed to address the urgent need for evidence and guidance on delivery of HR services and messaging for PWID during a pandemic.The review protocol was registered with PROSPERO .Databases searched between 10 and 14 August 2020 were PROSPERO, Cochrane, TRIP, Medline, PsycInfo, Web of Science, EMBASE, PubMed, OpenGrey, PLOS and Google Scholar, and Table Broad inclusion criteria were used as the scoping searches indicated a lack of peer-reviewed studies. Thus, grey literature, pre-publication and non-peer reviewed papers were also included as well as evidence suggested by experts in the field. The searches were, however, restricted to English language only.The scoping searches revealed a lack of evidence on messaging specifically directed at PWID, so a targeted search (via Google) was conducted for COVID-19-related HR messaging from key national public health bodies and drug service providers.The evidence was screened initially (RW) on whether the title alone appeared to have relevance to the research aim. The second screen (RW and AH) was based on abstract or summary and used the inclusion criteria detailed in Table Data were extracted into a spreadsheet recording study bibliographic details, HR intervention details and key findings relating to the research aim.As part of the rapid review approach, evidence was not subject to a robust quality appraisal but details of the type of evidence, study design and expert affiliation were extracted to allow a limited assessment of quality.A narrative synthesis approach was used to collate and describe the key findings from the evidence in relation to the research aim.In total, 121 pieces of evidence were identified, these included 106 from the systematic searches plus a further 15 from citation searching and the targeted search for HR messaging. After de-duplication, 86 pieces of evidence were entered into the second round of screening.Twenty-six pieces of evidence were excluded after abstract screening  were expert opinion pieces (of which most were academic experts).There were also 11 studies . In instances where multiple reports were available from the same study, this was included as one piece of evidence.There were four non-peer reviewed evidence reviews included.The review covered 16 pieces of grey literature classified as guidance, which included COVID-19-related HR messaging for PWID. This type of messaging was not always directly available on Government websites but they often sign-posted to messaging produced by reputable non-Governmental organizations (NGOs), think-tanks or service providers so these have been included.Based on the types of evidence included in the review, the quality would be considered low-moderate.Table Designating HR services as essential, so that they are not suspended in the event of a pandemic-type scenario, has been recommended by many experts , 8 and gBy designating HR as essential, these services can not only sustain their vital work but also offer additional functions . For insAn initiative to provide ‘essential journey’ cards, that PWID may use when collecting medications during lockdown to demonstrate their journey is essential, is yet to be evaluated but has been recommended by some authors , 17.Continued access to blood-borne virus (BBV) testing and treatment for PWID is vital to identify cases and reduce transmission ; innovatEmergency preparedness of HR services needs improving . This maNumerous papers have recommended ways in which HR services can remain open and comply with social distancing  such as In terms of NSP, various alternatives to conventional collection are possible. For instance, a UK study concluded that home delivery, provision by post, peer-supported distribution and vending machines should be considered . The autOther authors also recommend vending machines, which provide 24-h access, and no-contact collection , 8. The The Larney and Bruneau (2020) review of evidence from other ‘big events’ concluded that, in a pandemic-type scenario, NSP should offer as many needles and syringes to clients as requested and that flexible NSP, such as mobile or outreach models, will increase access . Other aSimilar to NSP, outreach and home delivery have been recommended for OST in a pandemic-type situation , 25. FleThis review found examples of new models of delivery of OST services. For instance, in Rhode Island USA, regulatory changes meant that initiation of OST by telephone could be developed; whilst the authors are positive about this approach, it has not yet been evaluated .In Ireland, a model of remote care has been developed which begins with an assessment of COVID-19 risk by telephone followed by a single-patient visit to local services to provide a point of care drug screen and complete necessary documentation. Contact episodes are maintained through remote video assessment and ongoing management by a primary care addiction specialist. This model is yet to be evaluated but it appears to offer lower COVID-19 transmission risks, increased access to OST and reduced waiting times .Much of the evidence makes recommendations around telehealth , 32, 33 One USA telehealth provider, Bicycle Health, has reported how it adapted its services to respond to COVID-19 guidance, such as urine testing via video link . HoweverSeveral authors suggested buprenorphine as a safer take home option than methadone , 31, 37 There is conflict between social distancing and the physically, socially and emotionally intimate nature of injecting drug use ; for insOne author suggests virtual injection supervision, which allows individuals to inject in the presence of an observer on the internet who is prepared to intervene in the event of an overdose or virtual peer support which also uses the internet to make social support available to PWID at a physical distance . AlternaSeveral authors have suggested ‘safe supply’  could provide a solution to the conflict between social distancing and HR , 41. OneMany authors highlighted the important role of pharmacies in delivering HR interventions during a pandemic-type situation if other services become unavailable , 43–45. Much of the evidence suggested that HR needs to be part of a holistic approach to supporting PWID during a pandemic-type situation. For instance, several authors have emphasized the need for enhanced mental health support for PWID, with video or internet-based psychotherapy and phone counseling generally recommended , 19, 38.Messages about how to access healthcare have been recommended as PWID may no longer have opportunistic access to treatment service staff and, therefore, may miss discussing wider physical health issues .Links to social and economic services were also emphasized as important. For instance, ‘Housing First’ was highlighted as an approach which can facilitate social distancing and provide stability for PWID to engage in HR and manage extended OST take home doses appropriately , 34. WitA pandemic-type scenario has the potential to exacerbate health inequalities already experienced by PWID, such as increased morbidity and mortality and reduced service provision . AdditioOverall, in the available evidence, there was little consideration of sub-groups within the population who inject drugs; one Ukrainian study considered older people as a sub-group of PWID finding that they need social support to engage in care  while anThe Larney and Bruneau (2020) review found few studies considered the impact of ‘big events’ specifically on women meaning there is limited evidence to inform women-specific and gender-sensitive COVID-19 responses for women who use drugs. They suggest this is important because women who use drugs are vulnerable to gender-based violence, and scarcity of drugs is likely to exacerbate conflict and risks of exploitation and/or victimization [Developing a communications plan, at individual service level, is suggested in the literature . Other aDue to the lack of evidence on HR messaging, a search was done of the communications provided during the COVID-19 pandemic by key national bodies and service providers. With the exception of the USA , GovernmImportant HR messages identified in this review can be grouped under the themes of infection control, and uncertain drug supply as detailed below: -Most of the messaging considered in this review included COVID-19-related hygiene advice, such as hand washing and cleaning surfaces –54. ThisCleaning the packages that drugs are supplied in  was covered in some messaging , 51, 52 Advice for PWID to prepare drugs themselves and avoid sharing equipment was common to almost all the messaging included in this review and was backed up with guidance around stocking up on supplies of equipment (such as needles and syringes) , 49–56. A Canadian expert group also suggest that public health messages around self-isolation and social distancing should be modified for people who use drugs, who live in shelters or who are involved in sex work . Some ofThe USA Government guidance explicitly recommends that PWID make use of the other services offered by NSP such as testing for BBV  while thAn international group of experts recommended that messaging needs to include information about overdose risks associated with changes in the quantity and quality of the drugs market  and mostMost messaging followed on from explaining the supply issue with advice about reducing the risk of overdose by accessing naloxone or by making a plan with family or friends to check in after using drugs , 53–56.Guidance on managing involuntary withdrawal, such as stocking up on medications to relieve symptoms, was mentioned in much of the messaging because of the risk of drugs being in short supply or PWID not being able to access them due to self-isolation –54.One of the UK service providers advises PWID to consider snorting rather than injecting during the pandemic as it is less risky when the quality of supply is unknown. They also suggest administering doses slowly when injecting to allow the drug to take effect, in order to reduce the likelihood of accidental overdose .This rapid review found 60 pieces of evidence relating to HR interventions and messaging in a pandemic-type situation and, through narrative synthesis, has identified the following implications for HR services, HR communication and further research.HR services should prepare for future pandemics by developing emergency plans and involving relevant PWID advocacy groups in redesigning services. This review focused on interventions so found little evidence on the role of operational partnerships, and working with organizations who support PWID, but these would be important for the implementation of, and may have implications on effectiveness of, interventions and messaging.Government and commissioning organizations should ensure that HR services are designated as essential and take action to facilitate maintained provision . There is no consensus from the evidence on which HR interventions to prioritize so local areas should base this on the needs of their population. As essential services, HR providers could take on additional functions such as screening clients for the pandemic infection and testing for BBV.To ensure equitable access, all NSP should be modified to enable social distancing  and should have a low threshold for supply of injecting equipment.A key message from the evidence is that complying with social distancing requires a more flexible approach to OST. This could be in terms of relaxing supervision and increasing take-home doses as well as considering more innovative ways of delivering OST services . However, action must be taken to mitigate possible widening of inequalities; this might include provision of mobile phones to clients or targeted use of peer supporters.Due to an increased risk of overdose , access Strong partnerships between HR services and other services  are needed in order to offer a holistic approach. For instance, HR services should work with homeless accommodation providers to ensure they can provide safe storage of medications and space for a safer use room.Evidence from an international group of experts concludes that consultation with PWID advocacy groups is needed when designing HR services that can respond to pandemic-type situations .Looking to the future, several authors suggest that the COVID-19 pandemic response has provided an opportunity for much needed change in the delivery of HR services , 35, 44.This rapid review found limited evidence on HR messaging during a pandemic-type situation but by including a targeted search of HR messaging from key national and service provider websites the following implications have been identified.HR services should develop a communications plan, which uses multiple channels, to employ in the ongoing COVID-19 response or future pandemic-type situations. However, relaying HR messages to PWID during a pandemic is so vitally important that government websites should include messaging directly for PWID and not rely on signposting to service providers or NGOs.HR messaging should include advice on issues of infection control and uncertain drug supply, as well as key information about accessing HR and other services to fit with a holistic approach; these messages are summarized in Fig. To meet an urgent need for evidence and guidance, this rapid review did not include a systematic quality assessment of the evidence but a brief appraisal revealed most was non-peer reviewed, pre-publication or expert opinion and so would be considered of low-medium quality. Thus, further research to evaluate the innovations and changes to HR services and messaging during the COVID-19 pandemic is urgently needed. This is particularly important as many experts feel that these changes should be sustained into the post-pandemic era so the impacts, both intended and unintended, require robust assessment. Additionally, the majority of evidence is opiate focussed, which likely reflects the main cohort accessing services, but suggests a need for further focussed work with non-opiate clients.This conclusion agrees with that of a rapid review conducted by the National Collaborating Centre for Methods and Tools in Canada, in that little evidence is available on the effectiveness of strategies to mitigate the harmful effects of illicit drug use during the COVID-19 pandemic . SpecifiAs previously stated, this rapid review presents preliminary findings of an emerging evidence base. It only includes evidence available until 14/08/2020. The COVID-19 pandemic is still ongoing and new evidence is becoming available all the time. Further robust systematic reviews are needed to confirm the findings as the evidence base expands.Searches were restricted to English language evidence only which is likely to have excluded useful evidence from areas such as Eastern Europe. In fact, much of the evidence was from the USA and Canada so is likely to be most applicable to higher-income countries.Time and resource constraints also meant that most of the searches, screening and data extraction was done by just one member of the review team. While this ensured consistency, it does risk bias in what evidence was included and excluded.In response to a lack of evidence on HR messaging, a targeted approach was taken to find additional messaging aimed directly at PWID from key national and services provider websites based on author knowledge of relevant national stakeholders. A further detailed, systematic search of the grey literature may glean more results, as would exploration of emerging channels of communication (such as apps) which were not explicitly investigated in this review.Preliminary findings from this rapid review suggest that HR services should be considered as essential during a pandemic and should be encouraged to operate flexibly to best meet the needs of their local community of PWID. Additionally, working with partners to offer holistic client-centered support is crucial.The evidence on HR communication during a pandemic is scarce but the targeted search has identified key messages around infection control, uncertain drug supply and accessing services which should be delivered via multiple channels.Of overarching importance is awareness of, and action to mitigate, exacerbation of inequalities through over-reliance on new remote and technology-based service delivery which may exclude the most marginalized.Additional file 1. Details of searches including database, search terms, number of hits and number eligible after first screen.Additional file 2. Key details of the included evidence such as author, title, source, type of evidence and a description of the harm reduction intervention or messaging covered.