Availability of Routine Vaccines in Primary Health Care Facilities in Sagbama Local Government Area, Bayelsa State, Nigeria: A Descriptive Cross-Sectional Study

Background: Routine immunization is one of the most cost-effective public health interventions for reducing morbidity and mortality from vaccine-preventable diseases, but its effectiveness depends on the consistent availability of vaccines at the point of service delivery. In riverine and hard-to-reach areas of Nigeria such as Sagbama Local Government Area (LGA) of Bayelsa State, empirical data on vaccine availability at the facility level remain scarce. This study assessed the availability of routine vaccines, the pattern of stock-outs, and the challenges affecting vaccine supply in primary health care (PHC) facilities in Sagbama LGA.

Materials and Methods: A descriptive cross-sectional survey was conducted across all 32 government-owned PHC facilities in Sagbama LGA using a census sampling approach. Data were obtained from health workers directly involved in immunization services using a structured questionnaire adapted from the World Health Organization Effective Vaccine Management tool, supplemented by review of facility stock cards and vaccine registers. Data were analysed with SPSS version 26 and summarised using descriptive statistics.

Results: Vitamin A (14.8%), Tetanus Toxoid (13.3%), Oral Polio Vaccine (11.4%) and Pneumococcal Conjugate Vaccine (10.0%) were the most consistently available vaccines, while Meningitis vaccine (1.9%), Pentavalent vaccine (4.3%) and Rotavirus vaccine (5.7%) were the least available. Most respondents (59.4%) reported that vaccines were not consistently available throughout the year, 43.8% reported stock-outs occurring more than five times annually, and 50.0% reported stock-out episodes lasting longer than one month. Poor electricity supply (22.2%), inadequate funding and logistics support (21.5%) and difficult terrain and transportation challenges (16.3%) were the leading barriers identified. Overall, 65.6% of respondents rated vaccine availability in their facilities as inadequate.

Conclusion: Routine vaccine availability in PHC facilities in Sagbama LGA is inadequate and inconsistent, driven largely by infrastructural and logistics-related barriers rather than an isolated cause. Strengthening cold chain infrastructure, supply chain forecasting, and transportation logistics for riverine communities is needed to improve immunization service delivery in the area.

Immunization is widely regarded as one of the most effective and cost-efficient public health interventions available globally, preventing an estimated 4 to 5 million deaths annually from vaccine-preventable diseases such as measles, diphtheria, pertussis, tetanus and poliomyelitis (WHO & UNICEF, 2022). Beyond mortality reduction, immunization contributes to improved quality of life, reduced healthcare costs and enhanced economic productivity. However, the effectiveness of any immunization programme is only as strong as the consistency with which vaccines are available at the point of service delivery. Vaccine stock-outs, even where caregivers are willing and health workers are trained, disrupt immunization schedules and erode public confidence in the health system (Ozawa et al., 2016).

Nigeria has made appreciable progress in strengthening its immunization system through the efforts of the National Primary Health Care Development Agency (NPHCDA), including expansion of cold chain infrastructure and increased government and donor funding (NPHCDA, 2022). Despite these gains, disparities in vaccine availability persist, particularly in rural and hard-to-reach areas, where interruptions in supply continue to contribute to missed opportunities for vaccination and suboptimal coverage (Eze et al., 2019; Afolabi & Abimbola, 2021).

Sagbama LGA in Bayelsa State presents a unique context for examining this problem. The area is predominantly riverine, with communities scattered across difficult terrain that is prone to seasonal flooding, making transportation of vaccines logistically demanding and increasing the risk of delay, spoilage and supply interruption. Anecdotal reports from the area suggest periodic vaccine shortages, yet there is limited empirical documentation of which vaccines are affected, how often stock-outs occur, how long they last, and what factors underlie them. This gap constrains the ability of local health authorities to design targeted, evidence-based interventions.

This study was therefore designed to assess the availability of routine vaccines in PHC facilities in Sagbama LGA, determine the frequency and duration of stock-outs over the preceding 12 months, and identify the challenges faced by health workers in maintaining consistent vaccine supply.

Study Design and Area

This was a descriptive cross-sectional survey conducted in Sagbama LGA, a predominantly riverine local government area of Bayelsa State, in the South-South region of Nigeria. The design allowed for the collection of data from multiple facilities at a single point in time, providing a snapshot of vaccine availability and stock-out patterns across the study area. At the time of the study, Sagbama LGA had 32 functional government-owned PHC facilities providing routine immunization services (Bayelsa State Ministry of Health, 2023).

Study Population and Sampling

The study population comprised health workers directly involved in immunization activities, including Community Health Extension Workers (CHEWs), nurses and vaccinators, across all 32 government-owned PHC facilities in the LGA. Given the relatively small and finite number of facilities, a census (total population) sampling approach was adopted, in which all eligible facilities were included, thereby eliminating sampling bias. Private health facilities and facilities not providing routine immunization services at the time of data collection were excluded.

Data Collection Instrument and Procedure

Data were collected using a structured questionnaire adapted from the World Health Organization Effective Vaccine Management (EVM) assessment tool and similar instruments used in comparable Nigerian studies. The instrument captured facility characteristics, availability of specific routine vaccines, stock-out frequency and duration over the preceding 12 months, and perceived challenges to vaccine supply. Content validity was established through review by experts in public health, immunization and research methodology, and the instrument was pilot-tested in a facility outside the study area with similar characteristics before deployment. The questionnaire was administered through face-to-face interviews with the officer-in-charge or immunization focal person at each facility, and responses were cross-checked against facility stock cards and vaccine registers where available.

Data Analysis

Data were coded and analysed using the Statistical Package for the Social Sciences (SPSS) version 26. Descriptive statistics, including frequencies and percentages, were used to summarise vaccine availability, stock-out patterns and reported challenges. Results are presented in tabular form.

Ethical Considerations

Ethical approval was obtained from the Research and Ethics Committee of Bayelsa State College of Health Technology, Otuogidi-Ogbia, and permission was secured from the Sagbama Local Government Primary Health Care Department prior to data collection. Informed consent was obtained from all participants, participation was voluntary, and no personal identifiers were collected; all data were reported in aggregate form.

Socio-Demographic Characteristics of Respondents

A total of 32 health workers, one from each of the 32 government-owned PHC facilities surveyed, participated in the study. Most respondents were female (62.5%), and the largest age group was 30 to 39 years (43.7%). Community Health Extension Workers constituted the majority of respondents (59.4%), and most had between 5 and 10 years of experience in immunization service delivery (59.4%).

Table 1: Socio-demographic characteristics of respondents (N = 32).

Source: Field survey, 2026.

Availability of Routine Vaccines

Vitamin A (14.8%), Tetanus Toxoid (13.3%), Oral Polio Vaccine (11.4%) and Pneumococcal Conjugate Vaccine (10.0%) were the vaccines most frequently reported as available across facilities. Pentavalent vaccine (4.3%), Rotavirus vaccine (5.7%) and Meningitis vaccine (1.9%) were the least available, while no facility reported having Malaria vaccine in stock.

Table 2: Availability of routine vaccines across facilities.

Source: Field survey, 2026.

Most respondents (59.4%) reported that routine vaccines were not consistently available throughout the year, while 40.6% reported consistent availability.

Table 3: Consistency of vaccine availability throughout the year.

Source: Field survey, 2026.

Stock-Out Patterns

Among facilities reporting inconsistent availability, Malaria vaccine (15.4%), Meningitis vaccine (13.5%) and Pentavalent vaccine (12.0%) were most frequently cited as being out of stock, while Vitamin A (0.5%) and Tetanus Toxoid (1.9%) were the least affected.

Table 4: Vaccines most frequently out of stock.

Source: Field survey, 2026.

Regarding frequency of stock-outs, 43.8% of respondents reported that stock-outs occurred frequently (more than five times yearly), 28.1% occasionally (3 to 5 times yearly), 15.6% very frequently (almost monthly), and 12.5% rarely (once or twice yearly). On duration, half of respondents (50.0%) reported that stock-outs typically lasted more than one month, and 28.1% reported a duration of 2 to 4 weeks.

Table 5: Frequency and duration of vaccine stock-outs.

Source: Field survey, 2026.

Challenges to Vaccine Availability

Poor electricity supply (22.2%) was the most frequently reported challenge to ensuring vaccine availability, followed by inadequate funding and logistics support (21.5%), difficult terrain and transportation challenges (16.3%), irregular supply from the LGA (15.6%), shortage of trained staff (12.6%) and inadequate cold chain equipment (9.6%).

Table 6: Challenges affecting vaccine availability.

Source: Field survey, 2026.

Health Workers' Perception of Vaccine Availability

Most respondents (65.6%) rated vaccine availability in their facility as inadequate, 28.1% rated it as adequate, and only 6.3% rated it as very adequate. When asked whether the current vaccine distribution system in the LGA was effective, 59.4% of respondents said yes and 40.6% said no.

Table 7: Health workers' rating of vaccine availability.

Source: Field survey, 2026.

This study found that routine vaccine availability in PHC facilities in Sagbama LGA is inconsistent, with 59.4% of health workers reporting that vaccines were not available throughout the year and 65.6% rating overall availability as inadequate. This finding is consistent with earlier reports identifying vaccine stock-outs as a persistent problem within Nigeria's immunization system (Afolabi & Abimbola, 2021; Eze et al., 2019).

The uneven availability across vaccine types is notable. Vitamin A and Tetanus Toxoid were comparatively well stocked, while Pentavalent, Rotavirus and Meningitis vaccines were markedly less available, and Malaria vaccine, still relatively new to the national schedule, was entirely unavailable at the time of the survey. This pattern suggests that supply-chain prioritisation, forecasting accuracy or distribution timing may differ by vaccine type, an issue that has also been reported at the national level (NPHCDA, 2022).

The frequency and duration data reinforce the scale of the problem: nearly half of the facilities experienced stock-outs more than five times a year, and half reported episodes lasting longer than a month. Disruptions of this length are long enough to compromise the immunization schedules of children requiring multiple, closely spaced doses, and are consistent with findings that prolonged stock-outs increase the risk of missed opportunities and outbreaks of vaccine-preventable disease (Okeke et al., 2020).

The challenges identified, poor electricity supply, inadequate funding and logistics support, and difficult terrain and transportation, are largely structural rather than related to health worker capacity or willingness. Poor electricity supply has direct implications for cold chain integrity, since vaccines require storage between 2°C and 8°C to retain potency (WHO, 2020). Similarly, the riverine and flood-prone terrain of Sagbama LGA compounds the transportation difficulties already documented in other remote parts of Nigeria (Kojima et al., 2020), underscoring the need for context-specific rather than generic supply-chain solutions in this setting.

Routine vaccine availability in PHC facilities in Sagbama LGA is inadequate and inconsistent, with frequent and often prolonged stock-outs affecting most facilities. The challenges underlying this pattern are largely structural, spanning electricity supply, funding, logistics and terrain, rather than being attributable to any single point of failure. Strengthening cold chain infrastructure, improving supply forecasting and distribution, and adapting transportation logistics to the riverine terrain of the LGA are needed to improve immunization service delivery and, ultimately, immunization coverage in this setting.

Recommendations

Based on these findings, it is recommended that vaccine supply chain forecasting, procurement and distribution to PHC facilities in Sagbama LGA be strengthened; that solar-powered cold chain equipment be deployed to address the impact of poor electricity supply; that transportation support, including boats and fuel, be provided for vaccine distribution to riverine communities; and that routine training of health workers in vaccine management and inventory control, alongside improved health information systems, be prioritised by relevant health authorities.

Limitations of The Study

This study has some limitations that should be considered when interpreting its findings. First, stock-out history over the preceding 12 months relied largely on the recall of health workers, which is subject to recall bias, although this was partly mitigated by cross-checking responses against facility stock cards and vaccine registers. Second, some facility records were incomplete or poorly maintained, which may have limited the extent to which self-reported data could be verified. Third, the study was restricted to government-owned PHC facilities and did not include private health facilities operating within the LGA, which may also contribute to immunization service delivery in the area. Fourth, the descriptive cross-sectional design permits only a snapshot assessment of vaccine availability and does not allow for the establishment of causal relationships between facility-level factors and vaccine stock-outs. Finally, because the survey captured perceptions and records at a single point in time, seasonal variation in vaccine availability, particularly around the rainy season when flooding most effects transportation in Sagbama LGA, could not be fully captured.

Contribution to Knowledge

This study contributes empirical, facility-level data on vaccine availability from a riverine and historically under-researched area of Bayelsa State, an area for which such localized evidence has previously been scarce. Rather than relying on national or regional aggregates, the study documents specific vaccines most prone to stock-out, the frequency and duration of these disruptions, and the structural barriers reported directly by frontline health workers responsible for immunization service delivery. In doing so, it extends the literature on supply-side determinants of immunization coverage in Nigeria and provides a context-specific evidence base that local health authorities, the Bayelsa State Ministry of Health, and the National Primary Health Care Development Agency can draw upon in planning targeted, rather than generic, interventions for riverine communities.

Implications for Public Health

The findings carry direct implications for immunization programming in Sagbama LGA and comparable riverine settings. Frequent and prolonged stock-outs of vaccines such as Pentavalent, Rotavirus and Meningitis vaccines translate into missed or delayed doses for children who require multiple, closely spaced immunizations, which can leave a growing pool of susceptible children and increase the risk of outbreaks of vaccine-preventable disease. The near-total unavailability of Malaria vaccine at the time of the survey similarly limits the anticipated public health benefit of its introduction into the national schedule. Because the leading barriers identified, poor electricity supply, inadequate funding and logistics, and difficult terrain, are structural rather than related to health worker knowledge or willingness, interventions aimed solely at health worker training are unlikely to substantially improve availability on their own. Instead, the results point to a need for investment in solar-powered cold chain infrastructure, terrain-appropriate transportation arrangements such as boats and fuel support, and more reliable forecasting and distribution from the LGA to facility level. Addressing these structural barriers would not only improve vaccine availability in Sagbama LGA but would also support broader national and global immunization targets, including the goals of the Immunization Agenda 2030, by closing a documented gap in service delivery to a hard-to-reach population.

Conflict of Interest

The authors declare no conflict of interest.

Funding

This study received no external funding.

Ethical Approval

Obtained from the Research and Ethics Committee of the Bayelsa State Ministry of Health.

Acknowledgements

The authors thank the health workers of the primary health care facilities in Sagbama Local Government Area for their participation in this study.