From Product Availability to Population Protection: Vaccine Deployment Readiness in Sierra Leone

Design and case selection

We conducted a comparative documentary analysis. The unit of analysis was the deployment pathway for a defined vaccine event, not Sierra Leone as a whole. The three cases were selected purposively. Each represents a distinct condition: deployment under global scarcity, deployment after inter‑emergency platform building and activation during a subsequent outbreak.

Sources and selection

We reviewed regulatory records, WHO, Gavi and government reports, and legal instruments. We also reviewed Sierra Leone’s COVID‑19 National Vaccine Deployment Plan, Joint External Evaluation and National Action Plan for Health Security. WHO readiness guidance and peer‑reviewed and preprint campaign analyses completed the set [8–38]. The search ran through 30 July 2026. It combined Sierra Leone with COVID‑19, Ebola or mpox, and added terms for authorisation, allocation, launch, coverage, readiness, logistics, workforce, surveillance and engagement. We checked reference lists and official sites.

Documents were included when they reported something dated or decided for one of the three events. This covered regulatory dates, allocation or procurement decisions, institutional functions, campaign milestones, target denominators and dated outcomes. Commentary without verifiable programme information was excluded. Public sources were supplemented by aggregate National Public Health Agency (NPHA) programme records, including Mpox Situation Reports 203 and 335.

The corresponding author extracted dates, outcomes and link‑specific evidence into a case matrix. The author team reviewed the chronology and the classifications and resolved discrepancies by consensus. Regulatory records supported authorisation dates. Vaccination registers and aggregate reports supported counts and denominators. Legal instruments supported mandates. Government and partner reports supported programme context.

Framework development and comparison

The 11 functions are drawn from Expanded Programme on Immunisation practices, emergency vaccination and WHO country‑readiness guidance [17, 18]. We organised them as an end‑to‑end pathway with named handoffs. Their boundaries are analytic conveniences. Functions interact and may operate in parallel. Community trust, for example, affects targeting, delivery and monitoring, as well as demand. The contribution is the sequence, ownership and timing, not the invention of the functions.

For each case, we recorded whether each link was operating before or during the launch. We also recorded whether it caused a delay and whether it was later strengthened and reused. We assigned a principal bottleneck in two situations only. The first was where a source named the main constraint. The second was where the chronology showed deployment waiting on that function while the others were available. Where the record did not support a category, Table 2 presents the evidence without one.

We measured two distinct outcomes. Time to the start of vaccination was measured differently in each case. For COVID‑19, it ran from European Medicines Agency (EMA) authorisation to the first national dose. For preventive Ebola, it ran from EMA authorisation to nationwide campaign start. For mpox, it ran from outbreak confirmation to operational vaccination start. Reach was the proportion of a stated target vaccinated by a stated date. Starting events differ between cases, so intervals are descriptive rather than a league table. Reach and start are reported separately throughout, because a fast start does not imply high reach.

Ethics and positionality

Ethics committee approval and informed consent were not required. No identifiable data were analysed. Three authors hold National Public Health Agency roles. Their access supported the chronology but creates a risk of favourable interpretation. We addressed it through public‑source triangulation, explicit uncertainty and no causal attribution to a single reform.

Case 1: COVID‑19 vaccination, 2021

Sierra Leone received its first 96,000 AstraZeneca doses on 8 March 2021. They came through the COVAX Facility, within an initial allocation of 528,000 doses. The first national dose was administered on 15 March, 45 days after EMA authorisation, granted on 29 January [23–25]. Frontline workers and adults older than 70 years were vaccinated first, before eligibility widened. The binding constraint at this stage was global. Scarcity and phased allocation determined how much vaccine the country could use, not how fast it could start.

National capacity shaped what followed. Ebola‑era regulatory pathways supported emergency authorisation of five COVID‑19 vaccines. Average processing time fell from 42 days in March 2020 to 11 days by the end of 2021. Ultra‑low‑temperature equipment procured for Ebola met national COVID‑19 needs, although facility‑level gaps remained [25].

By 17 May, 63 days after launch, 62,132 people had received a first dose and 7427 had received a second dose [25]. These counts describe the early phase, not the programme outcome. Full coverage among people aged 12 years or older reached 73.2% by December 2022 and a reported 86.7% by 31 October 2023 [25]. These census‑based estimates carry projection uncertainty. More than 84% of doses were delivered through 16 surge campaigns or periodic intensification. Surge teams expanded from 299 in the first three campaigns to 1385 in the final 13 [25]. The 45‑day interval marks a start. Comparable reach took about two and a half years.

Case 2: Nationwide preventive Ebola vaccination, 2024

Sierra Leone launched nationwide preventive Ebola vaccination on 5 December 2024 for frontline and high‑risk workers across all 16 districts [8, 9]. It was the first campaign of its kind in West Africa. Target groups included health workers, traditional healers, community health workers, laboratory staff, motorcycle taxi riders and security personnel.

The 1851‑day interval ran from EMA authorisation on 11 November 2019 to nationwide launch on 5 December 2024 [8–12]. It was not 1851 days of country delay. A global outbreak stockpile began in 2021. From 2021 to 2023, it shipped 145,690 doses, including 139,120 for high‑risk‑group prevention [16]. Sierra Leone had used the platform in 2015 and licensed Ervebo in eight districts in 2021 [14, 15]. Formal preventive policy came later. Gavi opened its preventive programme in June 2024 after the WHO first recommended preventive vaccination of health and frontline workers in high‑risk areas in May [9, 10]. The nationwide campaign followed in December. The interval therefore spans global policy and financing as well as national activation.

By December 2024, the pathway had aligned. Global preventive policy and financing were available [9, 10]. The Public Health Act supported coordination, Pharmacy Board approval supported national use and the National Public Health Agency provided an institutional home [15, 26, 27]. Earlier investment in surveillance, logistics, field epidemiology and engagement supported targeting, delivery and demand [14, 15, 29–31, 37]. Launch came about six months after Gavi opened the programme.

The campaign reached 17,454 of 20,621 targeted workers, 84.6%, in three weeks [15]. Health workers accounted for 6058 recipients and security personnel for 5312, and the social worker target was met. Although 67.2% of recipients were male, women had higher adjusted odds of vaccination (1.51, 95% confidence interval 1.29–1.76) [15]. This is consistent with the sex composition of the targeted occupational groups. At launch, the Minister of Health framed the campaign as part of the national health security agenda and as protection for frontline workers [8]. It was presented as infrastructure rather than as a single event. The chronology supports a chain‑wide institutional explanation. It does not establish that any single reform was sufficient on its own.

Case 3: Mpox clade IIb vaccination, 2025

Sierra Leone confirmed its first mpox case on 10 January 2025 and declared a public health emergency [13, 36]. The response combined vaccination with surveillance, case investigation, contact tracing, laboratory expansion, infection prevention, risk communication and clinical care. Partners secured 61,300 initial doses for health workers and hotspot communities [33].

WHO reported a formal campaign launch on 20 March 2025 [33]. A later programme account identified 26 April as the operational start of vaccination, 106 days after confirmation, and we use that endpoint [34]. Subsequent allocations raised available doses to 283,500 and widened eligibility to contacts and other high‑risk groups [34].

NPHA recorded 148,889 people vaccinated by 4 August against an operational target of 240,000, which is 62.0%, and 186,053 people vaccinated by 14 December [35, 38]. A Ministry report of 16 December stated that the outbreak had been declared over on 15 December [32]. December reports do not restate the August target. If that target still applied, the December total is 77.5% of it. The source counts, denominator, dates and qualifications are reproduced in Supplementary Tables S1 and S2.

The mpox interval begins with outbreak confirmation rather than authorisation, so it is not directly comparable with the other two. Its analytical value lies elsewhere. Programme reports link implementation directly to Ebola and COVID‑19 experience. The same coordination structures, workforce, logistics and engagement networks were reused rather than rebuilt [32–34].

Comparative findings

The three cases bind in different places. COVID‑19 started in 45 days. Reported full coverage reached 86.7%, but took about two and a half years and relied chiefly on surge campaigns and periodic intensification. Preventive Ebola vaccination began 1851 days after authorisation. That total interval included global policy and financing as well as national activation. Once the pathway aligned, the campaign reached 84.6% of its target in three weeks. Mpox activated an existing platform and expanded reach over eight months. Figure 2 separates start from dated reach, while Table 2 compares the 11 functions across the three events.

Figure 2

Three findings follow. Any unaligned link can hold the pathway. A fast start does not guarantee rapid reach. Capability built for one threat can be reused for the next.

Institutional change between the earlier and later events

Between 2019 and 2024, the record documents legal reform, the establishment of NPHA, workforce development, surveillance expansion, cold‑chain investment and partnership coordination [15, 25–27, 29–31, 37]. Table 3 traces these enabling conditions and their use in the 2024 campaign. The mpox response shows the same capabilities used again for a different pathogen.

Principal interpretation

Preparedness stops its clock too early. The 100 Days Mission target is not the problem. The absence of a matching country‑facing clock is. Product availability is necessary. It is not sufficient. The interval between the two is institutional.

Sierra Leone demonstrates this three times. COVID‑19 started in 45 days, but reported 86.7% full coverage took about two and a half years and repeated intensified delivery. Preventive Ebola vaccination began about five years after authorisation, then reached 84.6% of its target in three weeks. The interval included global policy and financing milestones, so it is total pathway latency rather than country delay alone. Mpox reached 186,053 people through a platform built for other diseases. The contrast makes the deployment gap visible without treating unlike intervals as a ranking.

Readiness is therefore a property of the connected system rather than of any capacity within it. An investment that strengthens one link while leaving the adjacent handoff untested buys less protection than its budget implies. The three cases support six claims about the deployment gap and about what closing it would require.

First, the gap lay across the deployment pathway, not in product availability

Product scarcity alone does not explain the Ebola interval. Ervebo had been authorised since 2019. A funded stockpile operated from 2021, and Sierra Leone had prior experience [9, 14–16]. Global policy timing is a rival explanation. Gavi opened its preventive programme in June 2024 after the WHO first recommended preventive vaccination of health and frontline workers in high‑risk areas in May [9, 10]. Sierra Leone launched nationwide vaccination in December. The 1851 days therefore span regulatory availability, global policy, financing and national activation. They are not 1851 days of national failure. The stronger finding is that product availability, stockpile access and prior use did not produce nationwide protection until the whole pathway aligned. COVID‑19 was bound first by global allocation. Mpox shows what happens when a reusable country platform exists.

Second, the pathway is reusable across threats

Successive versions of one national institutional platform carried three different products in four years. Coordination structures, workforce, logistics and engagement networks built for one threat were adapted for the next [15, 32–34]. Programme reports link the mpox response directly to Ebola and COVID‑19 experience. Threat‑specific investment underuses this property. Inter‑emergency periods are when the platform is built. A platform built once can serve the threat that has not yet arrived.

Third, urgency, population demand and international pressure act differently

The events faced different pressures. Urgency arose from active transmission. It was high during COVID‑19 and mpox, but lower for preventive Ebola vaccination. Population demand was separate. It included willingness, social support and practical access. The WHO behavioural and social drivers framework distinguishes motivation from access barriers [39]. In rural Sierra Leone, mobile delivery and community mobilisation increased COVID‑19 vaccination by about 26 percentage points within 48–72 hours [40]. Demand mattered, but the pathway still had to make vaccination reachable.

International pressure operated upstream. COVAX, scarcity and political attention shaped COVID‑19 allocation [5, 23–25]. During mpox, international partners supported dose mobilisation and coordination [32–36]. Ebola drew on stockpile financing and partner support [8, 9, 15, 16], but lacked the acute mobilisation of an active outbreak. These forces are not interchangeable. Urgency compresses decisions. Demand affects acceptance, attendance and return. International pressure accelerates financing, allocation and coordination. None creates cold chain, workforce or target denominators. We therefore treat all three as contextual influences, not Chain functions.

Fourth, deployment readiness can be measured

The 100 Days Mission has force partly because its target is a number. The next 100 days need comparable discipline. As further work, we propose two candidate measures. A deployment readiness score could assess the 11 links before an emergency. A deployment latency indicator could record days from a pre‑specified starting event to first dose, then from first dose to dated reach. The starting event must be named because authorisation, recommendation, financing and outbreak confirmation are not interchangeable. Neither measure is specified or validated here. Both require development, weighting, piloting and external validation.

Fifth, the chain nests inside existing readiness tools

JEE and SPAR assess International Health Regulations capacities across prevention, detection and response, including several on which vaccine deployment depends [20–22]. VIRAT/VRAF and national deployment and vaccination plans add vaccine‑specific detail on targets, supply, cold chain, sites, workforce, safety, recording and demand [17–19]. Sierra Leone’s own COVID‑19 National Vaccine Deployment Plan of October 2022 is a worked example [19]. It sets out coordination structures, prioritisation, cold‑chain capacity and gaps, workforce requirements, adverse‑event surveillance and data flows. These instruments are established, internationally accepted and already institutionalised in many countries. The Chain does not replace them.

What none of them does is time the whole pathway or name the institution that owns each handoff between one function and the next. A country can score well on capacity indicators and still wait years to deploy an authorised product. The indicators assess capacities separately rather than as a sequence. The Chain adds three things to what JEE and SPAR already produce. The first is the order in which functions must operate. The second is the institution accountable for each transition between them. The third is a dated measure of start and reach.

This makes integration straightforward. The 11 links can be populated inside an existing JEE or SPAR cycle rather than through a separate exercise. The JEE mission report supplies the capacity evidence. The Chain supplies the sequence, the ownership and the deadline. In practice, a country completing a JEE could add one page per link. Each page would record the lead institution, the alternate, the date the handoff was last tested and the time required to activate it. National action plans for health security would then carry deployment readiness as a costed line rather than as an implication.

Sixth, deployment readiness should be funded and governed as one object

Preparedness finance enters countries through separate legal, surveillance, laboratory, workforce and emergency windows [28, 41–45]. The first Pandemic Fund call received requests above US$2.5 billion but awarded US$338 million [41]. The Chain provides one line of sight across these investments. Between emergencies, it identifies weak links, owners and costs. During a threat, it tests whether investment produced a timely start and reach. CEPI, the Pandemic Fund, Gavi and parties to the WHO Pandemic Agreement could use it to assess deployment readiness alongside development speed. Treating the links as one fundable category connects regulation, logistics, targeting, workforce, safety, monitoring and demand.

Governance should follow the same logic. Countries that have built and used deployment pathways across successive emergencies hold operational knowledge the global architecture rarely draws on. Consultation is not the same as a seat. National public health agencies are well placed to hold this work, because they connect surveillance, emergency coordination and evidence use. Responsibility remains shared with ministries of health, regulatory authorities, EPI programmes, finance ministries, district teams, communities and partners.

National capability cannot substitute for equitable global access. Regional manufacturing, pooled procurement and transparent allocation shorten upstream delay. Financing, regulation, logistics, workforce, monitoring and trust determine national use. Preparedness requires both, and the next 100 days are where they meet.

Building the next 100 days between emergencies

Between emergencies, countries should populate all 11 links from JEE, SPAR, VIRAT/VRAF, national plans and programme records. Each link should be assigned a lead and an alternate institution. Regulatory reliance and emergency‑use pathways, financing mechanisms, stockpile access and customs triggers should be pre‑agreed rather than negotiated under pressure. Cold‑chain routes, target denominators, microplans, workforce rosters, safety protocols, data flows and engagement networks should be kept current.

The complete pathway should then be tested at least annually, using tabletop and field simulation with a defined product and target population. The exercise should require every handoff. It should record the time from product availability to first dose, and from first dose to dated reach. It should end in a costed corrective plan with an owner, a financing source and a deadline. Gaps should enter national health security and EPI plans, emergency budgets and partner agreements, and be retested until closed.