Health system determinants of vaccine cold chain performance at the primary healthcare facilities in Nasarawa State, Nigeria: a mixed-methods study

INTRODUCTION

Immunization is widely recognized as one of the most effective and cost-efficient public health interventions globally.^1,2 Its success, however, fundamentally relies on preserving vaccine potency throughout a strong cold chain system.³ Vaccines are temperature-sensitive biological products that must be maintained strictly within a recommended range of to +2°C to +8°C from the point of manufacture to administration.^4-6 Exposure to temperatures outside this range, even for short durations, can result in an irreversible loss of efficacy and increased vaccine wastage.⁴ Consequently, proper vaccine storage and continuous temperature monitoring are fundamental components of safe and effective immunization service delivery.

Despite global efforts and substantial investments to strengthen cold chain infrastructure in low- and middle-income countries, including Nigeria, maintaining an effective cold chain remains a significant challenge.^7-10 While the availability of equipment has improved, evidence suggests that infrastructure expansion alone may not guarantee effective temperature control under routine service conditions.^11-13 Studies in various Nigerian states have consistently documented persistent deficiencies, such as malfunctioning refrigerators, a lack of alternative power sources, and operational weaknesses at the primary healthcare (PHC) level.^7,14-16 These system weaknesses indicate that procedural compliance often coexists with operational risk, undermining the quality of immunization services.¹⁷

The effective performance of the cold chain is determined by a complex interaction of infrastructure reliability, human capacity, and system-level governance.^3,18,19 In Nasarawa State, immunization services are delivered largely through PHCs dependent on solar refrigeration systems.^20,21 However, there has been a limited recent, facility-level empirical evidence examining how infrastructure reliability and operational challenges interact to influence vaccine storage performance at this level of care.^1,22 The absence of such context-specific data limits the ability of programme managers to identify priority gaps and design targeted interventions.

Therefore, this study aimed to assess the health system determinants of vaccine cold chain performance at primary healthcare facilities in Nasarawa State, Nigeria using a mixed-methods approach.

METHODS

Study design and setting

This study employed a mixed-methods, cross-sectional design to evaluate the health system determinants of vaccine cold chain performance. The research was conducted across selected primary healthcare facilities in Nasarawa State, North-Central Nigeria. The setting included a diverse range of rural and urban PHCs providing routine immunization services under the supervision of the Nasarawa State Primary Healthcare Development Agency.²³ Data collection was carried out between August 2025 and September 2025.

Ethical consideration

Ethical approval for the study was obtained from the Nasarawa State Ministry of Health Research Ethics Committee. Administrative permission was further secured from the state’s primary healthcare authorities. Prior to data collection, all participants were briefed on the study’s purpose, and written informed consent was obtained. To ensure confidentiality, all identifiers were removed during data processing, and key informant interviews were conducted in private settings.

Participants and eligibility criteria

The study population for the quantitative component consisted of 147 healthcare workers directly involved in the Expanded Programme on Immunization (EPI), including nurses, midwives, and Community Health Extension Workers (CHEWs). For the qualitative component, 10 key informants were recruited, including State and Local Government Area (LGA) Immunization Officers and Cold Chain Officers. Eligible facilities were those actively providing routine immunization services and equipped with at least one vaccine storage unit.

Sampling and sample size

A multistage sampling design was utilized to ensure a representative sample. In the first stage, LGAs within Nasarawa State were selected via simple random sampling. In the second stage, PHCs were randomly identified from official facility registers. The minimum sample size of 127 was calculated using Cochran’s formula, based on a 90.9% expected proportion of cold chain component availability derived from previous regional studies. To account for potential non-response and enhance statistical power, a total of 147 healthcare workers were purposively enrolled from the selected facilities.

Data collection and study instruments

Quantitative data were collected using a structured facility-level self-administered questionnaire. These tools documented the availability and functional status of equipment, including refrigerators, solar-direct drive units, and backup power systems. Qualitative data were gathered through semi-structured key informant interviews (KIIs). These interviews explored contextual barriers and enablers, such as maintenance schedules, power supply stability, and governance structures. The data collection instruments were pre-tested for validity and reliability prior to the main study.

Data analysis and integration

Quantitative data were processed and analysed using IBM SPSS Statistics (version 31). Descriptive statistics (frequencies and percentages) were used to summarize equipment functionality, while Pearson’s chi-square tests (p<0.05) were applied to assess associations between infrastructure reliability and storage outcomes. Qualitative recordings were transcribed verbatim and analysed using NVivo 15 for thematic categorization. The findings were integrated through triangulation, where qualitative insights from stakeholders were used to explain and contextualize the quantitative gaps identified in the facility assessments.

RESULTS

A total of 147 healthcare workers from primary healthcare facilities in Nasarawa State participated in the study and 10 key informant interview participants. The characteristics of the survey respondents are summarized in Table 1.

The majority of respondents were female (n=98, 66.7%) and aged between 26 and 30 years (27.9%). In terms of educational attainment, 78.9% held a Diploma, while 19.7% possessed a BSc or HND. Professionally, the largest group of respondents had between 7 and 10 years of service (34.0%), indicating a sample with significant professional experience.

Analysis of the cold chain infrastructure (Table 2) revealed that the majority of refrigerators were functional (n=114, 77.6%), though nearly one-quarter (22.4%) were out of service at the time of the study.

The energy landscape was dominated by renewable sources, with 82.3% of facilities utilizing solar power as their primary energy source, while only 17.7% relied on the national grid or generators.

The assessment of management practices (Table 3) showed a significant gap between documentation and human resource capacity. While hundred and nineteen of facilities (81.0%) had Standard Operating Procedures (SOPs) available, seventy-four respondents (50.3%) reported they had never attended formal cold chain management training.

Qualitative findings from key informant interviews

Key informant profiles

To complement the quantitative data, 10 key informants were interviewed. These participants were purposively selected based on their leadership roles and specialized expertise in Immunization program. To ensure strict participant confidentiality, specific demographic details and job titles have been aggregated. The informants included ten senior-level professionals, comprising six males and four females, each possessing a minimum of 15 years of professional experience. This group provided the qualitative context necessary to triangulate the Table 2 survey findings.

Seven overarching themes emerged from the key informant interviews, describing the status of cold chain systems, temperature monitoring practices, human resource capacity, supervision mechanisms, and contextual barriers and enablers influencing cold chain performance at primary healthcare level in Table 4.

DISCUSSION

The findings of this study reveal a significant transition toward sustainable energy in Nasarawa State’s immunization program, alongside persistent operational and human resource challenges that threaten vaccine potency. A major strength identified is the widespread adoption of renewable energy, with 82.3% of primary healthcare facilities utilizing solar power as their primary energy source. This shift, supported by international partners like Gavi and UNICEF, represents a critical advancement in overcoming the historical barrier of unreliable national grid electricity in Nigeria. This high rate of solarization in Nasarawa consistent with findings reported by Kamala in Tanzania where equipment availability has improved through targeted regional assessments.¹ However, in contrast to this modernization, the data shows a resilience gap, where 41.5% of facilities still face daily power outages and 38.8% lack any backup power systems. This mirrors challenges identified by To et al. (2019) in Osun State where logistics management deficiencies persisted despite infrastructure pushes.² Furthermore, the observation that solar fridge temperatures rise to +10°C or +11°C during low sunlight aligns with findings by Falcón et al (2020) in Mexico where environmental factors frequently caused excursions outside the required +2°C to +8°C recommended range.¹⁷

A critical finding is the stark disconnect between the availability of guidelines and staff capacity. While 81.0% of facilities had standard operating procedures available, 50.3% of healthcare workers reported never attending formal cold chain management training. This high rate of untrained personnel is in alignment with systemic weaknesses identified by Dairo and Osizimete (2016) in Ibadan where provider practices were found to be more critical than equipment availability.¹⁶ This also mirrors the operational risks documented by Sow et al (2018) in Burkina Faso where procedural knowledge did not always translate to effective temperature monitoring.⁴ In contrast to the optimism expressed by Sasetu et al (2023) regarding the acceptability of peer learning in Nasarawa.²¹ This study suggests that informal support cannot replace formal capacity-building, as half the workforce remains untrained in core protocols.

Equipment maintenance remains a severe weakness, with only 55.1% of refrigerators serviced in the three months prior to the study. This confirms the findings of Babatunde et al (2020) in Oyo State where infrastructure expansion alone failed to guarantee effective control under routine conditions.¹⁴ The 22.4% non-functionality rate forces health workers to incur out-of-pocket expenditures for vaccine transport, a barrier that is in contrast to the more generalized system weaknesses cited by Burstein et al (2013) in their multi-country African study.⁵ Ultimately, the benefits of renewable energy are being lost due to a lack of human resource capacity and technical oversight. To secure the gains made in infrastructure, Nasarawa State must prioritize regular supportive supervision and systematic maintenance schedules to ensure vaccines remain potent from storage to administration.

The implications of these findings for vaccine potency and public health are substantial. The high frequency of power outages, combined with the lack of reliable backup power sources and limited human resource capacity evidenced by the large proportion of respondents without formal cold chain training (50.3%), creates a high-risk environment for temperature excursions and potential vaccine potency loss. This suggests that despite the solarization of cold chain infrastructure in the state, the benefits of renewable energy systems may not be fully realized without adequate technical oversight and trained personnel. Strengthening supportive supervision, identified by 34.7% of respondents as a key need, is therefore critical to improving compliance with cold chain management practices. From a policy and programmatic perspective, these findings highlight the need for targeted investments in workforce training, routine supportive supervision, and timely maintenance of cold chain equipment. In addition, strengthening backup power systems and ensuring sustained technical support for solar refrigeration systems would enhance the resilience of vaccine storage systems and help safeguard immunization programme performance at the primary healthcare level.

While this study provides valuable data on vaccine cold chain performance in Nasarawa State, it has some limitations. The survey relied on health workers reporting their own experiences, which could lead to social desirability bias where they might overstate their adherence to protocols. Second, the cross-sectional design only captured a "snapshot" of equipment functionality and power outages at one point in time, which may not reflect seasonal changes in sunlight affecting solar-powered systems.

CONCLUSION

The vaccine cold chain in Nasarawa State is characterized by a successful transition to renewable energy through widespread solar power adoption. However, significant gaps in human resource capacity and infrastructure reliability remain, as many staff members lack formal training, and numerous facilities operate without backup power systems. To ensure vaccine potency and program success, the state must move beyond equipment provision and prioritize regular supportive supervision, consistent equipment maintenance, and comprehensive capacity-building for healthcare workers.

ACKNOWLEDGEMENTS

Authors would like to thank the healthcare workers and cold chain handlers across Nasarawa State who participated in this study. Authors also acknowledge the support and cooperation of the Nasarawa State Primary Healthcare Development Agency and the management of the sampled primary healthcare facilities.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the Institutional Ethics Committee of the Nasarawa State Ministry of Health, Nasarawa State, Nigeria

REFERENCES

1. 1. Kamala SR, Nyembea H, Kalabamu FS, Ngonzi AJ, Manzi F, Nestory B, et al. Availability and quality of vaccine cold chain equipment at healthcare facilities in Mtwara region, Tanzania: evidence from routine assessment of vaccine cold chain equipment. Tanz J Health Res. 2025;26(3).
2. 2. To O, My I, Eo A, Oo A, Fo A, Am A, et al. Challenges in the Logistics Management of Vaccine Cold Chain System in Ile-Ife, Osun State, Nigeria. 2019;31(2):1-2.
3. 3. Maureen IA, Ugwu DC, Egwuenu A, Muhammad FS, David I. Challenges and innovations of vaccine cold chain distribution in developing countries: a narrative review. IJRSI. 2026;12(12):1404-17.
4. 4. Sow C, Sanou C, Medah C, Schlumberger M, Mireux F, Ouédraogo I, et al. Challenges of cold chain quality for routine EPI in south-west Burkina-Faso: An assessment using automated temperature recording devices. Vaccine. 2018;36(26):3747-55.
5. 5. Mulatu S, Tesfa G, Dinku H. Assessment of factors affecting vaccine cold chain management practice in Bahir Dar City Health Institutions, 2019. AJLS. 2020;8(5):107.
6. 6. 6. Kartoglu U, Ames H. Ensuring quality and integrity of vaccines throughout the cold chain: the role of temperature monitoring. Expert Revi Vaccines. 2022;21(6):799-810.
7. 7. Oyadiran OT, Usman SA, Osoba ME, Olukorode SO, Lucero-Prisno III DE. Towards effective and efficient COVID-19 vaccination in Nigeria. J Glob Heal Rep. 2021;5.
8. 8. Bogale HA, Amhare AF, Bogale AA. Assessment of factors affecting vaccine cold chain management practice in public health institutions in east Gojam zone of Amhara region. BMC Publ Heal. 2019;19(1):1433.
9. 9. Adeyemo KS, Mbata AO, Balogun OD. The role of cold chain logistics in vaccine distribution: addressing equity and access challenges in sub-Saharan Africa. IJMRGE. 2021;2(1):893-901.
10. 10. Sinnei DK, Karimi PN, Maru SM, Karengera S, Bizimana T. Evaluation of vaccine storage and distribution practices in rural healthcare facilities in Kenya. J of Pharm Policy and Pract. 2023;16(1):25.
11. 11. Wanyonyi EN, Sagwa E, Banzimana S, Asingizwe D. Vaccine storage and stock management practices in Vihiga County, Kenya. J of Pharm Policy and Practice. 2024;17(1):2337128.
12. 12. Yakum MN, Ateudjieu J, Walter EA, Watcho P. Vaccine storage and cold chain monitoring in the North West region of Cameroon: a cross sectional study. BMC Res Notes. 2015;8(1):145.
13. 13. Sinha AK, Verma AR, Chandrakar A, Khes SP, Panda PS, Dixit S. Evaluation of cold chain and logistics management practice in Durg district of Chhattisgarh: pointer from Central India. Int J Commu Med Publ Heal. 2017;4(2):390.
14. 14. Babatunde OA, Olatunji MB, Omotajo OR, Ikwunne OI, Hamzat Z, Sola ST. A comparative assessment of cold chain management using the outbreak of circulating vaccine-derived polio virus type 2 as a surrogate marker in Oyo State, Nigeria-2019. Pan Afr Med J. 2020;37:313.
15. 15. Burstein R, Dansereau EA, Conner RO, DeCenso BM, Delwiche KP, Gasasira A, et al. Assessing vaccine cold chain storage quality: a cross-sectional study of health facilities in three African countries. The Lancet. 2013;381:S25.
16. 16. Dairo DM, Osizimete OE. Factors affecting vaccine handling and storage practices among immunization service providers in Ibadan, Oyo State, Nigeria. Afr H Sci. 2016;16(2):576.
17. 17. Falcón VC, Porras YVV, Altamirano CMG, Kartoglu U. A vaccine cold chain temperature monitoring study in the United Mexican States. Vaccine. 2020;38(33):5202-11.
18. 18. Tlhakanelo JT, Ataguba JEO, Pagiwa V, Ramabu N, Kadimo K, Muriithi GN, et al. A qualitative analysis exploring barriers and enablers to distribution, delivery, and access to COVID-19 vaccines in Botswana. Front Health Serv. 2025;5:1609056.
19. 19. Olutuase VO, Iwu-Jaja CJ, Akuoko CP, Adewuyi EO, Khanal V. Medicines and vaccines supply chains challenges in Nigeria: a scoping review. BMC Public Health. 2022;22(1):11.
20. 20. Dalhatu MY, Ango KKB. Primary Healthcare Delivery in Rural Areas of Nasarawa State, Nigeria: Accessibility Survey. 2021;5(12):43-49.
21. 21. Sasetu S, Mbachu C, Addulkarim D, Iliya S, Ezumah N, Odonye C, et al. Acceptability of peer learning and support for strengthening routine immunization data in Nasarawa State, Nigeria. Niger J Clin Pract. 2023;26(Suppl 1):28–35.
22. 22. Sadru G, Makhado M, Swalehe O, Banzimana S, Asingizwe D, Maru SM. Assessment of vaccine management performance in health facilities of Mwanza Region, Tanzania: a cross-sectional study. J Pharm Policy and Pract. 2023;(1):144.
23. 23. Isah MA, Ajidani MS, Ebigye SE, Maryam AG. Effect of community effort on economic development in Nasarawa State, Nigeria. 2022;6(6).