Hepatitis C is a silent disease because symptoms are often delayed for many years, sometimes decades. This epidemiological feature hinders the detection of the disease, being a major challenge in finding and diagnosing individuals living with hepatitis C. People who inject drugs (PWID) are one of the populations that have higher reported HCV prevalence rates.Footnote 1 The lifestyle of PWID has also been identified as related to higher HCV transmission, such as drug injection and needle/syringe sharing.

Hepatitis C is recognized as a disease with a strong social impact on PWID, as it is common to find patients with a criminal record, and many are imprisoned due to strict drug-related legislation (Lafferty et al. 2021). Lifestyle factors greatly increase the probability of contracting hepatitis C, and it can be aggravated when there are comorbidities (e.g. alcohol and drug addiction, mental disorders, HCV or HIV infections, etc.) (Abara et al. 2019; Molinaro et al. 2019; Amoako et al. 2021; Butt et al. 2021; EMCDDA 2021). Social problems such as unemployment, homelessness, unstable housing, social and family isolation, sex work or even criminal actions arise in this population, representing higher risk factors for poor health conditions (Larney et al. 2020; Arum et al. 2021; Butt et al. 2021; EMCDDA 2021). The conjugation of these conditions makes hepatitis C among PWID a serious global public health issue.

In most countries, the percentage of undiagnosed patients is estimated to be high (Mangia et al. 2021; WHO 2022), with data suggesting that around two-thirds of PWID are living with HCV infection (ECDC 2021). This rate is heterogeneous both within and between countries, with anti-HCV antibodies among PWID in North America estimated to be between 40 and 68% (Degenhardt et al. 2017; Grebely et al. 2019). In contrast, in Europe, it ranges between 18 and 80% (EMCDDA 2019; Stasi et al. 2020; ECDC 2021). Furthermore, it is estimated that approximately 9% of all HCV infections are related to recent drug injections among PWID (Grebely et al. 2019). It should be noted that epidemiological data can be underestimated for this population, mostly due to living on the health system’s fringe, which poses a great challenge in attracting individuals to formal healthcare services.

The development of direct-acting antiviral (DAA) therapies has changed the hepatitis C treatment paradigm, potentially achieving a sustained virologic response of approximately 100% (Cornberg and Manns 2022). Also, the short time of the DAA therapy duration, taken orally and with little to no side effects, represents an appealing treatment opportunity for unprivileged populations (Ortiz-Paredes et al. 2022). However, to reach this care cascade (CC) stage, efforts in finding and diagnosing new HCV cases must be strengthened (EMCDDA 2021). Only by reinforcing the first steps of the CC for hepatitis C will it be possible to attain the WHO’s elimination goal for the disease by 2030 (WHO 2016). This strategy is aligned with the micro-elimination approach for hepatitis C, in this case, directed to PWID, resorting to the active involvement of key stakeholders (Lazarus et al. 2018; Lanièce Delaunay et al. 2021). For this purpose, clinicians, government officials and policymakers with the expected input of the community, epidemiologists and public health experts have been developing intervention programmes to attract people living with HCV infection, such as PWID, to healthcare services. However, despite the scientific developments of DAAs, there have not been enough corresponding advances in public health policies (PHP) that attract target populations to diagnose and link them to treatment until the achievement of SVR0. Finding integrated public health solutions focussed on this population is an opportunity to strengthen the bond between different healthcare services. For example, strengthening interventions to find and diagnose individuals living with the disease while integrating point-of-care and linkage-to-care process initiation in hepatitis C services (e.g. medical, psychological, social, etc.) for newly diagnosed HCV-positive infected individuals (EMCDDA 2021; Ortiz-Paredes et al. 2022; WHO 2022). With the growth of managed care plans responsible for specific populations, the healthcare system is becoming a more suitable vehicle for achieving public health goals. This is seen in clinical preventive services that find clinical and social solutions for patients, thus fostering PWID best practices. Therefore, knowing the fundamental role in finding and diagnosing PWID who may be living unaware of their hepatitis C condition towards achieving the HCV goal by 2030, public health solutions must be strengthened to control the disease in this population.

The high dropout rate of PWID between each hepatitis C’s CC phase is also known (van Dijk et al. 2020). At INSHU 2018, the proposal of 90:90:90:90:90 was presented, which means that it should be sought to ensure that the dropout rates should not exceed 10% between phases of the hepatitis C’s CC (Krekulova et al. 2022), as opposed to the current rates that reach approximately 50% (van Dijk et al. 2020). This article focusses on the first three steps (awareness, prevention and diagnosis), which, being among the initial ones in hepatitis C’s CC, will partly determine the success of the remaining steps. Although no concrete values are known for the number of individuals in the early stages of the CC, field experience provides information regarding the difficulty in finding new PWID living with hepatitis C (Martínez et al. 2021).

COVID-19 added further complexity to the great efforts of countries towards achieving the WHO’s hepatitis C elimination goal by 2030 (Smith 2022). As such, urgent action is required to prevent the loss of all the previous efforts and strengthen strategies in finding and diagnosing individuals living with hepatitis C, especially in vulnerable populations such as PWID. If this strategy is not adopted, new infections among PWIDs will not allow the disease’s elimination goals and control in the community. Therefore, PHP tools must be developed to support the decision-making of politicians related to health, health authorities and organizations in the field, especially in the early steps of the hepatitis C’s CC, for each target population, towards recovering delays in achieving the Sustainable Development Goals (SDG) established by the General Assembly of the United Nations.

The prevention of hepatitis C should follow the same procedures as in other diseases by implementing measures that promote literacy in all its forms (Lopes and McKay 2020). The absence of hepatitis C signs and symptoms in most people for many years contributes to individuals who live with hepatitis C often being unaware of the existence of this disease and its transmission pathways (Solomon et al. 2015; Pimpin et al. 2018; Metwally et al. 2021). Furthermore, once the diagnosis is achieved, this may also promote less commitment from patients in addressing the disease, despite being associated with a major mortality cause among PWID due to liver disease (Yang and Muir 2021). This is aggravated by low literacy recurrence in this population, especially in closed communities (DeCuir et al. 2018; Metwally et al. 2021). The lack of knowledge about a disease, its associated risks and perceived lack of urgency in seeking care can lead to low adherence to interventional campaigns, screening tests and other preventive or control measures (Marshall et al. 2017; Walters et al. 2020; Amoako et al. 2021). Awareness through education is a key element in disease prevention, especially among high-risk populations, as knowledge dissemination allows capacitating individuals as active agents of their health by promoting the understanding of awareness as prevention (Schrauben et al. 2020) and healthier behaviours, addressing misconceptions and concerns while reducing risk behaviours and identifying risks related to the disease transmission (Scott et al. 2017; Lopes 2018; Buggisch et al. 2021; Metwally et al. 2021). In awareness and prevention actions, health, well-being and disease literacy and training are crucial for all the involved social actors in strategies focussed on hepatitis C, from PWID to social workers and health professionals (Amoako et al. 2021). Considering that nobody knows the PWID lifestyle (e.g. habits, avoidance strategies, etc.) as well as PWID themselves, the sharing of common language and experiences allows for peer evidence-based educational interventions to be a key measure in attracting and maintaining patients throughout the different CC phases (Deuba et al. 2020; Mabuie 2020; Schwarz et al. 2022).

Raising awareness about hepatitis C for policymakers is also important in guaranteeing adequate legislation and programmes for the disease, especially in developing strategies and resource allocation. Prevention must be achieved by optimizing information management processes and alerting target populations, those around them and all the people involved in this public health issue. To this end, it is important to proactively ensure access to social services and improve PWID’s social, economic and political environment to maximize gains in public and individual health (Torrens et al. 2020). The aforementioned elements allow for a more adequate preparedness to interact with PWID since the first contact points are to foster action and preparedness concerning individuals from this population along the disease CC steps (Martínez et al. 2021). Point-of-care approaches may also take advantage of places with closer contact with the PWID population, such as harm reduction services, primary healthcare services and prisons.

A “cure as prevention of spreading” model can also be used with the new direct-acting antiviral (DAA) therapies for hepatitis C due to a rate of individual viral elimination of approximately 100%. However, the link between general literacy and hepatitis C awareness is of such importance that we consider prevention measures before treatment efforts, reinforcing this reading based on the health literacy scientific literature. This approach is of the utmost importance to address PWID’s potential concerns and misconceptions about the treatment and its side effects, namely those related to the Interferon treatment era (Amoako et al. 2021).

The greatest risk of HCV transmission is related to sharing needles, syringes and other paraphernalia (Curado et al. 2022), thus having a great need to be addressed. While needle and syringe programmes (NSP) are a primary source of clean injecting equipment, some PWID reported secondary distribution as a main source, considered a high-risk behaviour as they were more likely to share needles (Noroozi et al. 2017). The syringe exchange programmes aim to reduce the risk of HCV transmission by regularly providing enough syringes, complete injection kits to individuals with risk behaviours, advising on how to avoid those risks, linkage to maintenance therapy, among others (Miller et al. 2019; Palmateer et al. 2022). For example, the implementation of NSP in Europe was associated with a reduction in HCV transmission by over 70% (Palmateer et al. 2022).

A recent study supported these interventions, stating that high coverage of NSP among PWID could reduce HCV acquisition risk by half if more than one sterile needle and syringe were returned per reported injection (Ward et al. 2018). However, the effect of distributing syringes among PWID is not linear, in the sense that one cannot expect a direct and proportional effect based on the number of needles/syringes distributed. Some authors identified the need to micro-segment the patterns of syringe use (Jacka et al. 2020). While the exchange of used syringes for new ones will delay HCV spread among high-risk PWID patients, prevention in low-risk PWIDs can have a more determining effect. Therefore, the risk assessment normally based on incidence and prevalence rates could not be adjusted to PWID in reality.

Despite difficulties being identified in all the hepatitis C’s CC steps for the PWID population, the main challenge for HCV’s adequate management is to diagnose the entire population of HCV infected individuals (Amoako et al. 2021). Globally, HCV testing and diagnosis are inadequate, showing a great need to intensify the effectiveness of diagnosis strategies (EMCDDA 2021; WHO 2022). This might be partly explained by individuals’ anxiety, stigma and fears towards screening actions for hepatitis C (EMCDDA 2021). Such reactions underline the need for additional counselling support to facilitate testing and referral of chronically infected individuals, with a need for improvements across the general practice for patients to be retained in care (Baptista-Leite et al. 2024). The integration of health services will also greatly contribute to adequate linkage-to-care after a first hepatitis C diagnosis by making the referral process simpler and more agile. Globally, it was estimated that 90% of patients chronically infected with HCV reside in resource-limited settings (Mohd Hanafiah et al. 2013; Solomon et al. 2015), with all that is implied in terms of access equity for health care and aggravated conditions. However, in these contexts even a great isolated clinical solution is insufficient. In countries where HCV prevalence is poorly documented, it is of the utmost importance to have national programmes (planned, financed, politically supported and implemented) that address awareness, screening, interventions and treatment strategies. Recruitment and follow-up of PWID in the community are not easily achieved due to the aforementioned factors, such as people not being willing to be diagnosed, selecting the best tools to collect samples, not having suitable veins and other factors (Chevaliez et al. 2020; EMCDDA 2021).

An important strategy in finding and diagnosing PWID living with HCV infection is to implement point-of-care screening and diagnosing tests for HCV in places frequented by PWID, such as harm-reduction services (Saludes et al. 2019; Chevaliez et al. 2020; WHO 2022). For this approach, the dried blood spot (DBS) test has been identified in the literature as easy to collect due to the use of an auto-retracting disposable sterile lancet, used for voluntary HCV testing with similar specificity and sensibility to HCV-RNA (Saludes et al. 2019; Chevaliez et al. 2020). The utility of using DBS samples as a monitoring test is described in the literature as feasible, with specificity and sensitivity rates of approximately 100% for HCV (Saludes et al. 2019; Chevaliez et al. 2020). It has been suggested that DBS has the potential to measure key epidemiological features among community-recruited PWID samples and allows differentiation between individuals with cleared infections, ongoing infections and those recently infected.

A more efficient strategy should include outreach hospital care, point-of-care and linkage-to-care, only using necessary tests (HCV-RNA), for example, at the end of therapy and the three subsequent months. Performing tests that enable virus characterization at genotype and nucleotide levels may greatly enhance PWID populations’ public health surveillance. Moreover, fingerstick tests, including viral load assessment and non-invasive assessment of liver fibrosis (APRI, FIB-4, mobile FibroScan®, mobile ultrasound), street doctors and nurses, social technicians and peers’ coaching should be available to this population. All the aforementioned measures are examples of evidence models of care for drug services (EMCDDA 2019) and are aligned with the updated recommendations on hepatitis C care from the WHO (WHO 2022) and EMCDDA (EMCDDA 2021). It is fundamental that these approaches are accompanied by strong surveillance systems that allow for evaluating and tailoring adequate strategies for different contexts (Lazarus et al. 2021; Mirzazadeh et al. 2021).

InterventionsFootnote 2 are among the most efficient field approaches to identifying new HCV cases (and other diseases), fostering higher test uptakes and diagnosis rates while sensitizing target populations about the pathology, good hygiene and prevention practices (Scott et al. 2021; Ortiz-Paredes et al. 2022; Palmateer et al. 2022). Knowing that HCV is a silent disease with often late-onset symptoms, people living with HCV infection can be unaware of their condition, making interventions an important procedure in diagnosing new hepatitis C cases.

Considering the above, the present paper aims to create a toolkit – APPEALFootnote 3 – to strengthen the awareness, prevention and diagnosis steps of the disease’s CC towards controlling hepatitis C in PWID by supporting organizations to reflect on their practices, identify possible issues and find adequate solutions for their specific ecosystems.