1.1 Introduction
Immunization is defined as the process by which a person is made resistant to infectious diseases, typically through the administration of vaccines that stimulate the body's immune system to develop protection against specific pathogens (World Health Organization, 2023). It is regarded as one of the most cost-effective and life-saving public health interventions in modern medicine, particularly in reducing morbidity and mortality among children under five years of age.
In modern primary health care systems, immunization is a core preventive strategy designed to protect children from vaccine-preventable diseases such as measles, polio, diphtheria, tuberculosis, hepatitis B, and whooping cough. These diseases have historically contributed significantly to childhood deaths globally, especially in low- and middle-income countries where access to health services is limited (UNICEF, 2023).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are significance of the study, scope of work, research hypothesis and questions, limitation of the study and definition of terms.
1.2 Background of Study
Historically, immunization as a major preventive measure against childhood diseases in modern primary health care systems can be traced back to early attempts at disease prevention before the development of modern vaccines. According to the World Health Organization (WHO, 2023), the concept of immunization began with the practice of variolation, which involved the deliberate exposure of individuals to small amounts of infectious material to induce mild infection and subsequent protection. Centers for Disease Control and Prevention (CDC, 2022) asserted that, the success of the smallpox vaccine led to widespread vaccination campaigns across Europe and North America in the 19th and early 20th centuries. The CDC stated that these efforts eventually resulted in the global eradication of smallpox in 1980, which remains one of the greatest achievements in public health history.
World Health Organization (WHO, 2022) stated that, the expansion of immunization programs gained significant momentum in the mid-20th century with the development of vaccines for diseases such as diphtheria, tetanus, pertussis, tuberculosis, and polio. WHO affirmed that the establishment of the Expanded Programme on Immunization (EPI) in 1974 marked a turning point in global health efforts, aiming to ensure that all children have access to life-saving vaccines regardless of geographical or socio-economic barriers. According to UNICEF (2023), the integration of immunization into primary health care systems was strengthened following the Declaration of Alma-Ata in 1978, which emphasized primary health care as a key strategy for achieving “Health for All.” UNICEF reported that immunization became a core component of primary health care delivery, especially in developing countries where child mortality rates were high due to preventable diseases.
According to Gavi, the Vaccine Alliance (2022), the introduction of new vaccines in the late 20th and early 21st centuries, including vaccines for hepatitis B, Haemophilus influenzae type b (Hib), rotavirus, and pneumococcal disease, further expanded the scope of immunization programs. Gavi stated that these advancements significantly reduced childhood mortality and morbidity globally, especially in low-income countries supported by international partnerships.
World Bank (2021) affirmed that, investments in immunization infrastructure such as cold chain systems, vaccine logistics, and health workforce training have played a critical role in strengthening primary health care systems. The World Bank contended that countries with sustained investment in immunization programs tend to achieve better health outcomes and stronger disease prevention capacity. According to recent global health reports, immunization continues to evolve with advancements in biotechnology, including mRNA vaccine development and improved vaccine delivery systems (WHO, 2023).
In modern primary health care systems, immunization has become a cornerstone of preventive health services, ensuring that children are protected from vaccine-preventable diseases from infancy through adolescence. Its historical development reflects a continuous effort to improve child survival and reduce global health inequalities through accessible and effective vaccination programs. This study is set against the backdrop of the persistent burden of childhood diseases despite global advancements in immunization coverage and the need to strengthen primary health care systems for improved vaccine delivery and uptake.
1.3 Statement of Problems
In many rural and urban poor communities, immunization programs is not fully utilized due to misconceptions about vaccine safety, cultural beliefs, and lack of trust in the health system. The persistence of these conditions places a heavy burden on families, health facilities, and the national health system, leading to increased child morbidity and mortality rates (Centers for Disease Control and Prevention, 2022).
On the other hand, even where immunization services is available, inconsistent outreach programs and inadequate follow-up mechanisms reduces the effectiveness of immunization coverage, thereby leaving gaps in herd immunity and exposing children to preventable diseases.
Furthermore, primary health care systems that is expected to serve as the first point of contact for immunization services is often faced with challenges such as shortage of skilled health workers, insufficient cold chain equipment, and irregular vaccine supply. As a result, preventable childhood diseases continues to pose a significant public health concern, undermining child survival goals and sustainable development efforts (World Health Organization, 2023). It is against this backdrop that this study seeks to examine immunization as a major preventive measure against childhood diseases in modern primary health care systems.
1.4 Aim and Objectives of Study
The aim of the study is to examine immunization as a major preventive measure against childhood diseases in modern primary health care systems using selected primary health care facilities in Lagos State, Nigeria.
The specific objectives of the study are to:
- Examine the availability of immunization services in primary health care centres in Lagos State.
- Assess the level of immunization coverage among children under five years in Lagos State.
- Identify factors affecting the uptake of immunization services among caregivers.
- Evaluate the challenges faced by health workers in delivering immunization services.
- Determine the effectiveness of immunization in reducing childhood diseases in Lagos State.
1.5 Research Questions
Based on the stated objectives, the study will address the following research questions:
- What is the level of availability of immunization services in primary health care centres in Lagos State?
- What is the level of immunization coverage among children under five years in Lagos State?
- What factors affect the uptake of immunization services among caregivers?
- What challenges do health workers face in delivering immunization services?
- How effective is immunization in reducing childhood diseases in Lagos State?
1.6 Research Hypotheses
In order to pursue the objective of this study, the following generalized statements have been designed to guide and aids in obtaining the result for the experiment to be conducted. For this work, the null hypothesis will be represented with H0 while the alternative hypothesis will be represented with hypothesis H1.
Hypothesis 1
- H0: Immunization services does not significantly reduce childhood diseases in Lagos State
- H1: Immunization services significantly reduces childhood diseases in Lagos State
Hypothesis 2
- H0: There is no significant relationship between caregiver factors and immunization uptake in Lagos State
- H1: There is a significant relationship between caregiver factors and immunization uptake in Lagos State
Hypothesis 3
- H0: Health system challenges does not significantly affect immunization service delivery in Lagos State
- H1: Health system challenges significantly affect immunization service delivery in Lagos State
1.7 Significance of Study
The outcome of this research will provide factual evidence on the effectiveness of immunization in reducing childhood diseases in primary health care systems. Also, health policy makers will use the findings to improve immunization planning and resource allocation for primary health care systems.
Furthermore, health workers will benefit from improved understanding of barriers affecting immunization delivery and will improve service efficiency. In addition, Government health agencies will use the findings to strengthen monitoring and evaluation of immunization programs.
Lastly, researchers will use the study as a reference for further studies on childhood immunization and disease prevention.
1.8 Scope and Limitations of the Study
The study focuses on immunization as a major preventive measure against childhood diseases. It covers immunization coverage, service delivery, caregiver factors, and challenges affecting vaccine uptake among children under five years.
The study is limited to selected primary health care facilities in Lagos State and does not cover secondary or tertiary health institutions. It focuses only on routine childhood immunization services and excludes other forms of medical interventions.
1.9 Definition of Terms
Immunization:
Immunization is the process by which individuals are protected against infectious diseases through the administration of vaccines that stimulate immunity against specific pathogens (World Health Organization, 2023). It is a key preventive health intervention that reduces child morbidity and mortality.
Primary Health Care:
Primary Health Care is defined as essential health care that is universally accessible to individuals and families in the community through acceptable means and at affordable cost (WHO, 2023). It serves as the first level of contact with the health system.
Childhood Diseases:
Childhood Diseases refer to infectious diseases that commonly affect children under five years, including measles, polio, diphtheria, tuberculosis, and whooping cough (UNICEF, 2023). These diseases is largely preventable through vaccination.
Vaccine Coverage:
Vaccine Coverage is the proportion of the target population that has received recommended immunizations within a defined period (CDC, 2022). It is used to measure the success of immunization programs.
Vaccine Hesitancy:
Vaccine Hesitancy is defined as delay in acceptance or refusal of vaccines despite availability of vaccination services (WHO, 2022). It is influenced by misinformation, cultural beliefs, and distrust in health systems.
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