Our analysis is based on case studies of four pooled procurement mechanisms: The Organisation of the Eastern Caribbean States (OECS), the Pacific Island Countries (PIC), the Global Drug Facility (GDF) and the Asthma Drug Facility (ADF). Further information on general characteristics, historical background and in-depth analyses of each individual pooled procurement mechanism can be found in the supplementary materials (Additional files 1, 2, 3 and 4).

In the following sections, we have highlighted important findings that emerged from our comparative case-study analysis, explaining the success or failure of the included pooled procurement mechanisms. We explore how the key components of a pooled procurement mechanism, which include the way the buyers, the budget, the pooled procurement organization and suppliers are organized, incentivized and interact with each other. In this section, we do not expand on all essential elements identified in the Pooled Procurement Guidance [10] for each case-study. Instead, we highlight the essential elements that were critical for the success or failure of these mechanisms. A comprehensive overview of the presence, partial presence or absence of the essential elements for each case study can be found in Table 2 and in the supplementary materials.

Table 2 Comparative overview of the presence, partial presence and absence of the essential elements within the case studiesThe problem, the politics and motivations to participate

Before establishing any pooled procurement mechanism, it is imperative that potential buyers, such as high burden countries, and other key actors in the global health arena, such as global health organizations and donors, experience the problems for which pooled procurement may be a solution. If and how these key actors experience the problems that need to be solved, depends on multiple factors.

In the case of Tuberculosis (TB), the combination of three main factors created the preconditions to raise global attention: the nature of the disease, the high disease burden, and the possibility to cure TB with the right treatment. TB is an airborne communicable disease caused by the Mycobacterium tuberculosis. The bacteria are transmittable from human-to-human and can lead to death if left untreated [16, 17]. TB has a high global disease burden. The World Health Organization (WHO) estimates that a quarter of the world population has a TB infection, with 30 high burden TB countries, mainly low- and middle-income countries, accounting for 90% of the TB cases [17]. Currently, TB is estimated to cause 1.6 million deaths per year [18]. The development of an effective multi-component treatment strategy, called DOTS (Directly observed treatment, short-course), was an important breakthrough for curing people with TB [16]. However, many high burden TB countries experienced challenges in implementing the DOTS strategy. These challenges included lack of financial resources to procure TB medicines, lack of access to high quality TB medicines, inefficient procurement systems, lack of national TB programs, a small market size for TB medicines and diagnostics, and limited human resources to accurately diagnose and treat TB [19,20,21].

In 1993, TB climbed its way up on the global health agenda after the WHO declared TB a global health emergency, acknowledging that the spread of TB could only be contained if a universal approach would be taken [22]. This global attention brought many key actors together, including global health organizations, high burden TB countries, donors and NGOs. One important initiative that emerged from this multi-actor engagement in the battle against TB was the Stop TB Partnership [19, 23]. This partnership led to the establishment of the Global Drug Facility (GDF). The GDF was set up to solve the problems of lacking high quality and affordable TB medicines, which was seen as an important barrier in the rapid expansion of the DOTS strategy [19, 24, 25].

Increased global awareness, the availability of external funding, which we’ll discuss in the next section, and the multi-stakeholder approach put TB also on the national agenda of potential buyers. These buyers realized that pooled procurement, as organized by the GDF, could provide a solution to the problems they experienced in the fight against TB.

In the case of the Asthma Drug Facility (ADF), these preconditions for global awareness and multi-actor engagement were lacking to a large extent. An estimated 262 million people worldwide are affected by asthma causing approximately 461,000 deaths annually [26]. In contrast to TB, however, asthma is a non-communicable disease caused by a chronic inflammation of the airways with no cure. Asthma treatment is mainly focused on symptom relief [27]. The lack of perceived urgency to treat asthma in the global health arena and in potential buyer countries, mainly low- and middle-income countries, have been attributed to multiple factors. In many of the potential buyer countries these include insufficient health services around chronic diseases, poor access to accurate diagnostics, inaccurate demand forecasting of asthma treatments, a lack of context-specific national programs, guidelines and training on asthma, and inadequate knowledge among clinicians and the general public on the diagnosis, disease, treatment and management of asthma [14, 27,28,29,30,31,32,33]. One of our respondents confirmed that low- and middle-income countries did not perceive asthma as an urgent problem:

“Countries did not see what problems Asthma Drug Facility was able to solve for them, because they did not see any problem: for them asthma was not an issue.” [Procurement agent].

As a result, the ADF experienced difficulties with creating sufficient global awareness on the problems around treating asthma, constructing a global health infrastructure to congregate key actors, attracting external funding, and convincing potential buyers to focus on detecting and treating asthma. The ADF tried to provide a solution with high quality and affordable medicines to problems that were not equally perceived as urgent by other key actors.

Motivations to participate

However, even if a pooled procurement mechanism manages to provide a solution to urgent problems, the perceived urgency of the problem in itself is not sufficient for buyers to participate in a pooled procurement mechanism. The motivations to participate in such a mechanism need to outweigh the costs of participation. For example, some Pacific Island Countries (PIC), who procure their medicine from other countries in the Pacific region with whom they have had a strong historical relationship, such as Australia and New Zealand, showed little motivation to participate in an inter-country pooled procurement mechanism [34,35,36]. In addition, some PIC were concerned that the additional distribution costs of a potential inter-country pooled procurement mechanism, and the high costs of integrating administrative, political and bureaucratic structures would outweigh the financial benefits that the inter-country pooled procurement mechanism would generate [37, 38].

The GDF, on the other hand, does not merely operate as an intermediate organization that consolidates demand and carries out pooled procurement. It also provides a rounded procurement service to incentivize buyers to participate in the mechanism. For example, the GDF provided grants to eligible buyer countries at initiation [19]. Currently, a Flexible Procurement Fund (FPF) provides financial flexibility to buyers that have difficulty to adhere to GDF’s prepayment conditions [39]. The GDF also supports buyer countries with capacity building and technical assistance in several areas, including demand planning and stock monitoring [20, 40, 41]. The GDF and the Stop TB Partnership, under which the GDF is housed, both operate under the United Nations umbrella. This institutional backing legitimized GDF’s operations and provided the GDF high-level access to high burden TB countries. Reciprocally, the GDF involves representatives of high burden TB countries in its governance mechanism as board members of the Stop TB Partnership [23, 42]. This governance structure increased the buyer’s trust in the GDF. GDF’s user-friendly services with high client satisfaction ratings [21], combined with a positive track record of increasing access to quality-assured and affordable TB medicines have reinforced the GDF’s positive reputation to attract and incentivize potential buyers to procure through its pooled procurement organization.

The findings show us that in order to establish pooled procurement mechanisms successfully, it is essential for buyers and other key actors in the global health arena to experience an urgent problem for which pooled procurement may provide a solution. This perceived problem should generate sufficient political will from buyers. In addition, the buyers’ motivations to participate in the mechanism should outweigh their costs of participation. Finally, the proposed solution (i.e., the operational model of the pooled procurement mechanism) should be compatible with the experienced problems.

Securing sufficient, predictable and timely budget

The presence of sufficient, predictable and timely budget, either internal or external (i.e., through donors) is needed to both procure medicines and to cover organizational expenses. Securing this budget depends heavily on the key actors’ perception of the problem, their motivations to participate and their political willingness and power to act on the problem, as discussed in the previous section. In addition, this budget is required at all levels (i.e., the buyer level, the inter-country level, and the pooled procurement organization level), which we will further specify in the following section.

Allocating internal budget at the buyer’s level relies on the potential buyer’s perceived urgency of the problems that the pooled procurement mechanism aims to solve. Often, the limited internal budget that is available in low- and middle-income countries, especially for non-communicable diseases, has to compete with other more urgently perceived (communicable) diseases, as seen in the examples of the ADF. Attracting external funding relies mainly on the perceived urgency of the problems by donor countries or organization, as seen in the example of the GDF. The nature of TB, which spreads from human-to-human through air poses a potential health threat for higher income countries. This threat, in combination with the high disease burden and the fact that TB is curable with the right treatment, allowed the “TB-sector” to attract a significant amount of external funding from donor organizations and development aid from high-income country foreign ministries.

In buyer’s mechanisms, a collective sufficient and stable budget at the inter-country level is required. The importance of this collective budget became evident in the PIC example, where a lack of agreement and coordination of PIC’s budget was influenced by a lack of agreement on which currency to use and the absence of an appropriate and trusted financial organization in the region that could coordinate the financial process [37, 43].

In contrast, the member countries of the Organisation of the Eastern Caribbean States (OECS) share a common currency and succeeded in establishing a revolving fund at the inter-country level, managed by the Eastern Caribbean Central Bank (ECCB). These preconditions created a trusted and user-friendly mechanism to transfer money resulting in OECS members to deposit one-third of their annual internal pharmaceutical budget to individual country drug accounts at the ECCB [44]. This was a clear demonstration of political will from OECS members at initiation of the mechanism.

The pooled procurement organization or secretariat that carries out the procurement also requires sufficient, predictable and timely budget to both procure medicines and to cover organizational expenses. These organizational expenses might include salaries of staff, office rent, maintaining IT systems, daily management tasks and organizing meetings. While inter-country pooled procurement mechanism like OECS and PIC relied mainly on the buyer’s internal budget, disease-specific third-party pooled procurement organizations were more likely to target external funding to procure medicines. Some were successful like the GDF, and some unsuccessful like the ADF, for the reasons explained above.

Similarly, organizational expenses have been covered with internal budgets, mainly through service fees, or external, through donor funding. The OECS inter-country pooled procurement mechanism was set up in 1986 with initial support from USAID, which provided technical assistance and covered its operating costs for the first couple of years [45, 46]. After the initial funding, the organization became self-sustaining in 1989 through relying on service fees, which was incrementally reduced from 15% to 1986 to its current level of 9% since 2016 [46, 47]. Similarly, the ADF aimed to sustain its secretariat by adding a mark-up to every order [36]. But due to a lack of incoming orders, the International Union Against Tuberculosis and Lung Disease (The Union), under which ADF was housed, had to bear the costs of ADF’s operations. This financial burden eventually resulted in The Union terminating ADF’s operations in 2013, before the ADF could reach its aim of financial sustainability [14]. The GDF, on the other hand, relies mostly on external funding from USAID, secured through congressional budget, to cover organizational expenses of its secretariat [48, 49].

We can conclude from the above that sufficient, predictable and timely budget is needed at all levels of the pooled procurement mechanism, both to procure health products and to cover organizational expenses. Securing sufficient budget is highly connected to the key actors’ perceptions of the problem, their motivations to participate and their political willingness and power to put the problem on the national and global agenda.

Continuous alignment of goals, purpose and operations

In a buyer’s owned pooled procurement mechanism, in which the buyers manage the operations of the mechanism more collaboratively compared to a third-party organization pooled procurement mechanism, the buyers need to continuously align on goals, purpose and operations of the mechanism. Alignment does not necessarily mean that all buyers need to have the same goals, purpose and operations for the mechanism. But alignment can still be achieved as long as the goals, purpose and operations of different buyers are not conflicting.

In the case of the OECS, all buyer countries experienced similar problems, such as a small market size, limited availability of health products, relatively high costs of procurement of health products, and a limited efficiency of procurement and supply management [50,51,52]. These shared problems resulted in converging needs for OECS members, facilitating the alignment on goals, purpose and operations of the pooled procurement mechanism. For example, the similarity of characteristics between OECS members in population size, demographics and financial capacity results in a common need to increase their market size and a joint need for specific products. Agreeing on these products is a deliberate process that requires continuous work and alignment. The products are listed in the Regional Formulary and Therapeutic Manual and are reviewed annually by the Technical Advisory Committee [50]. In addition, OECS member’s geographical location as remote island nations and their small population size generates the common need to reduce (distribution) costs and increase availability of health products. The relatively high homogeneity of OECS member characteristics related to their needs allowed the OECS to set up a central contracting mechanism, the most integrated form of pooled procurement.

Similar to OECS, the Pacific Island Countries (PIC) consist of a broad range of remote and dispersed island nations in the Pacific Ocean. Unlike OECS, the characteristics of PIC are more heterogeneous related to their needs. This heterogeneity is particularly apparent when comparing the PIC’s population size, demographics, financial capacity, currency, and health outcomes. which might translate in different needs for health products, increasing the difficulty of product alignment [53,54,55]. The PIC’s divergence in buyer’s characteristics related to their needs, has contributed to misaligned goals, purpose and motivations among PIC. The motivations for smaller island states (SIS) were mainly to increase access to affordable medicines by increasing their market size, whereas Fiji’s driving force to participate was mainly to become the leading country of the inter-country pooled procurement mechanism, expressing concerns about their sovereignty if they were not provided with this leading role [37]. However, other PIC, such as the Solomon Islands have resisted the idea of Fiji taking a leading role in the inter-country pooled procurement mechanism, partially because of past experiences of failed collaborations, e.g. the attempt in 1971 to set up a joint airline, called Air Pacific which fell apart because many PIC, particularly the Solomon Islands, believed that the airline was mainly benefitting Fiji [56]. Although there have been successful examples of collaboration initiatives in the Pacific region, such as the Forum Fisheries Agency and the South Pacific Tourism Organisation [56], the negative experiences have made PIC reluctant to rely too much on others within the inter-country pooled procurement mechanism. Inevitably, these failed collaborations have impacted the level of trust between Pacific Island Countries. Also, the great diversity in culture, tradition and languages between the PIC might have had an impact on these trust levels [57, 58]. The fragility of the trust level between PIC were underlined recently, when five PIC of the Micronesian sub-group quit the Pacific Islands Forum over a dispute on selecting the Forum’s new Director-General [59]. As seen in the examples above, the history of collaboration among buyers, and the presence of pre-existing organizational and political structures can influence the alignment of buyers and creation of pooled procurement mechanisms. These collaboration efforts can reinforce trust among the buyers, as seen in the OECS example, or reduce trust, as seen in the PIC example.

Our findings show that relative and continuous alignment on products, goals, purpose and operations between buyers is essential. This alignment is heavily influenced by the homogeneity of buyers’ characteristics, their experienced levels of trust and their experiences in collaboration. This is especially important for a buyer’s mechanism, because buyers often participate directly in the management and operations of the pooled procurement mechanism.

Clear organizational structure of the secretariat

Our analysis showed that the pooled procurement mechanisms that were still operational relied on the presence of a dedicated secretariat with clear roles and responsibilities. For example, the OECS Pharmaceutical Procurement Service (PPS) is run by a permanent secretariat with dedicated staff. All buyer countries are represented through the policy board of the PPS. Procurement is carried out by various committees with clear task divisions and integrated safeguards to limit the possibility of conflicts of interest [44, 45, 50].

Similarly, the GDF is run by a dedicated secretariat with sufficient human resource capacity. The GDF secretariat consist of around 40 staff members, of which around 30 are based at the headquarters in Geneva, Switzerland; and the remaining staff operating externally in different regions, mainly in high burden TB countries. The staff of the GDF are highly trained and highly specialised, focusing on many areas, including TB advocacy, market shaping, sourcing, stakeholder alignment and coordination, demand forecasting and quantification, technical assistance and capacity building, tendering, contract management with suppliers, oversight of quality assurance, warehousing, distribution, and data management [60]. GDF’s organizational structure with a dedicated secretariat, sufficient in numbers and expertise, allows the GDF to provide a rounded procurement service. In addition, the GDF involves representatives of high burden TB countries, global health organizations, international donors and technical agencies in its governance mechanism as members of the Stop TB Partnership Coordinating Board. This structure, where a wide variety of stakeholders take part in GDF’s operations, contributes to legitimizing GDF’s operations in the buyer countries, and provides an arena that facilitates continuous alignment of goals and incentives [23, 61].

In contrast, the Asthma Drug Facility (ADF), another disease-specific third-party organization pooled procurement mechanism, lacked a clear organizational structure and dedicated staff to carry out the pooled procurement of asthma treatment. The ADF was housed under The Union and was run by a small in-house team. However, according to our respondents, ADF’s in-house team had to carry out procurement and related tasks on top of their already existing duties and responsibilities for The Union, impeding their output.

Incentives for suppliers

Besides buyers, the pooled procurement organization, and a sufficient and predictable source of funding, suppliers are essential for the functioning of the pooled procurement mechanism. The suppliers (i.e., manufacturers, wholesalers and distributors) produce and supply health products to buyers via the pooled procurement organization or secretariat. For suppliers to participate in the mechanism, buyers and the pooled procurement organization need to sufficiently incentivize suppliers. Parmaksiz et al. [10] have made a distinction between production and supply incentives. Production incentives incentivize suppliers to specifically produce products for the buyers in the particular pooled procurement mechanism, whereas supply incentives incentivize suppliers to supply products that are already being produced by the supplier for other markets, to the buyers in the pooled procurement mechanism.

The OECS pooled procurement mechanism was set up to procure relatively high demand essential medicines [44, 50]. Since these products were already being produced in high volumes by suppliers, providing sufficient production incentives was less relevant for OECS members. Instead, OECS members had to provide sufficient supply incentives for suppliers to supply these essential medicines to the Eastern Caribbean Island nations. These supply incentives included a centralized payment mechanism, standardized and transparent procurement processes, enforced participation of OECS members creating a public sector monopsony, a consolidated market, a generally positive reputation, and long-term framework agreements [44, 45, 50, 62].

Although both the OECS and the Pacific Island Countries (PIC) consist of island nations, there are important difference between the two regions. The PIC are more geographically remote and dispersed, increasing delivery times and distribution costs [35, 37]. Also, the prices of medicine in the Pacific Islands region were already relatively low. For example, Vanuatu and Solomon Islands already achieved lowered medicine prices compared to the OECS pooled procurement mechanism [