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Caregiver Socio-Demographic Factors That Influence the Uptake of
Third and Fourth Doses of Malaria Vaccine Among Under-Fives in
Muhoroni Sub-County, Kenya
*Joshua Nyarango, Dr. Doreen Maloba Othero, Prof. Collins Ouma
Department of Public Health, Maseno University, Kenya
*Corresponding Author
DOI: https://doi.org/10.51244/IJRSI.2025.120800165
Received: 07 Aug 2025; Accepted: 13 Aug 2025; Published: 17 September 2025
ABSTRACT
Malaria remains a leading cause of morbidity and mortality among children under five in sub-Saharan Africa,
accounting for approximately 90% of childhood malaria deaths (WHO, 2023). The RTS, S/AS01E malaria
vaccine, administered in four doses at 6, 7, 9, and 24 months, has shown moderate efficacy in reducing clinical
and severe malaria (WHO, 2022). Despite promising outcomes, uptake of the third and fourth doses remains
suboptimal in Kenya, particularly in high-burden areas such as Muhoroni Sub-County, where coverage drops
from 72.1% for the first dose to 31.4% for the fourth dose (Okanda et al., 2023). Understanding
sociodemographic factors that influence the poor uptake of third and fourth vaccine to dose uptake is critical
for sustaining malaria prevention gains.
An analytical cross-sectional study employing mixed methods was conducted among 289 caregivers of
children aged 9–60 months who had completed the first two doses of the malaria vaccine in Muhoroni Sub-
County. Stratified random sampling was used to select participants. Quantitative data were collected via
structured questionnaires and analysed using SPSS v27. Descriptive statistics summarized uptake patterns,
while Chi-square tests and logistic regression identified predictors of third and fourth dose uptake at a 95%
confidence interval. Qualitative data from key informant interviews were thematically analysed using NVivo
software.
The uptake of the third dose was 50.9% (n=147), while only 10.4% (n=30) received the fourth dose. Higher
caregiver education was significantly associated with third dose uptake (OR=1.27; 95% CI: 0.56–2.89;
p=0.043). Greater distance to health facilities reduced the odds of third dose uptake by 81% (OR=0.19; 95%
CI: 0.11–0.31; p<0.001). Cultural beliefs discouraging vaccination were negatively associated with uptake of
the third dose (χ²=11.17; p=0.001), while the perception that children receive “too many vaccines” was linked
to lower fourth dose uptake (χ²=4.17; p=0.041). Qualitative findings reinforced these results, highlighting
logistical barriers, misinformation, and limited community engagement as key obstacles.
Third and fourth dose uptake of RTS, S/AS01E remains far below WHO targets in Muhoroni Sub-County.
Education level, proximity to health services, and socio-cultural perceptions significantly influence uptake.
Targeted strategies, including community-driven awareness campaigns, improved vaccine accessibility, and
culturally sensitive health messaging, are essential to close the late-dose coverage gap and reduce malaria-
related child mortality.
Keywords: Malaria vaccine, RTS, S/AS01E, third dose, fourth dose, uptake, socio-demographic factors
INTRODUCTION
Malaria continues to be a leading cause of morbidity and mortality in low- and middle-income countries
(LMICs), with children under five bearing the greatest burden (WHO, 2023). Globally, nearly half of the
population is at risk, with approximately one million malaria-related deaths annually—nine in ten occurring in
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sub-Saharan Africa’s young children【WHO, 2023】. Beyond its health impact, malaria imposes significant
social and economic costs, particularly among rural, low-income households (Elnour et al., 2023; Watts et al.,
2021).
In Kenya, malaria remains a persistent public health concern despite the implementation of the National
Malaria Policy and the Kenya Malaria Strategy, which aim to achieve >90% immunization coverage in
endemic areas and reduce malaria-related morbidity and mortality by 75% from 2016 levels by 2023. The
RTS, S/AS01E malaria vaccine—endorsed by the World Health Organization in 2021—offers a novel
preventive tool when integrated with existing interventions such as insecticide-treated nets, chemoprophylaxis,
and prompt case management【WHO, 2022】. Administered in four doses at 6, 7, 9, and 24 months of age, the
vaccine has demonstrated moderate efficacy in reducing clinical malaria by 39% and severe malaria by 29%
(Praet et al., 2021).
However, evidence from Western Kenya, including Muhoroni Sub-County, indicates substantial drop-off in
vaccine uptake after the initial doses. Data show coverage rates of 72.1% for the first dose, 59.4% for the third
dose, and only 31.4% for the fourth dose (Okanda et al., 2023). These figures fall short of both national and
WHO targets, undermining the vaccine’s potential impact in high-transmission areas such as the Lake Victoria
region. Previous studies have linked low uptake to factors such as limited caregiver awareness, logistical
challenges, vaccine stock-outs, negative provider attitudes, and socio-cultural beliefs (Grant et al., 2022; Hoyt
et al., 2023).
Given the high malaria burden in Muhoroni and the observed disparities in late-dose coverage, there is a
pressing need to investigate the barriers specific to third and fourth dose uptake. Such insights are vital for
designing targeted, context-sensitive interventions to enhance immunization completion and reduce malaria-
related child mortality.
METHODS
Study design and setting
An analytical cross-sectional study employing both quantitative and qualitative approaches was conducted
between June and July 2025 in Muhoroni Sub-County, Kisumu County, Kenya. Muhoroni is predominantly
rural, with a population of 154,116 and a high malaria transmission intensity, situated within the endemic Lake
Victoria basin. The sub-county covers approximately 658 km², comprising two divisions, 10 locations, and 35
sub-locations. A sample size of 289 respondents obtained using Fishers sample determination formula was
interviewed.
Study population
The study population comprised caregivers of children aged 9–60 months who had completed the first two
doses of the RTS, S/AS01E malaria vaccine. The target population was 14,726 caregivers, distributed across
41 Community Units (CUs) in the sub-county.
Inclusion and Exclusion Criteria
The study included caregivers who had resided in Muhoroni Sub-County for at least one year and were
responsible for children aged 9–60 months who had received the first two doses of the malaria vaccine.
Caregivers with severe medical conditions that prevented participation, as well as those whose children were
too ill to participate during the study period, were excluded.
Sample Size Determination and Sampling Procedure
The sample size was determined using Fisher’s formula, based on an estimated malaria vaccine uptake
prevalence of 75%, a 95% confidence level, and a 5% margin of error, resulting in a total of 289 caregivers.
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Stratified random sampling was used to ensure representation from all 41 CUs, proportionate to population
size.
Data Collection
Quantitative data was collected using structured, pre-tested researcher-administered questionnaires covering
socio-demographic characteristics, health service factors, and socio-cultural beliefs.
Qualitative data was obtained through Key Informant Interviews (KIIs) with the Kisumu County Director of
Health Services and the Medical Superintendent of Muhoroni Sub-County Hospital, using semi-structured
interview guides.
Data collection was conducted by the principal investigator and four trained research assistants, with
supportive supervision to ensure data quality
Data analysis
Quantitative data were entered and analysed using SPSS version 27. Descriptive statistics summarized socio-
demographic characteristics and uptake patterns. Chi-square tests assessed associations between variables and
vaccine uptake. Variables with p<0.05 in bivariate analysis were entered into logistic regression models to
identify independent predictors, with results reported as odds ratios (ORs) and 95% confidence intervals (CIs).
Qualitative data from KIIs were transcribed verbatim and analysed thematically using NVivo software,
allowing triangulation with quantitative findings.
Ethical Considerations
The study adhered to the Declaration of Helsinki ethical principles. Approval was obtained from the Great
Lakes University of Kisumu Scientific and Ethical Review Committee (GLUSERC). A research permit was
granted by the National Commission for Science, Technology, and Innovation (NACOSTI). Written informed
consent was obtained from all participants. Confidentiality was maintained by assigning unique codes in place
of personal identifiers, and participation was voluntary with the option to withdraw at any time without
penalty.
RESULTS
Participants characteristics
The study targeted a sample of 289 participants of whom all were accessible; hence, a response rate of 100% is
reported herein. The mean age of the caregivers was 42.02±2.442 years, whereas the mean age for children
was 27.11±2.45 months. Amongst the caregivers, most of them 71 (24.6%) reported to have one (1) child.
More than average; 154 (53.3%) of the caregivers reported that their children were up to date with malaria
vaccination as scheduled.
Regarding other immunizations, 254 (87.9%) of the caregivers reported that their children were up to date with
all other required immunizations. On diagnosis with malaria in the last six (6) months, a high proportion; 130
(45.0%) observed that their children had been diagnosed with malaria, but it was not severe. When it came to
seeking treatment, it was slightly above average; 155 (53.6%) reported that they sought treatment from
hospital. Almost all of the participant; 274 (94.8%), reported that they received information (Table 1).
Table 1. Participant Profile
n=289
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Characteristic
n
Percentage (%)
Up to date with malaria vaccine schedule
No
135
46.7
Yes
154
53.3
Up to date with other immunizations
Yes
254
87.9
No
35
12.1
Diagnosis with malaria last 6 months
No
93
32.2
Yes, and it was severe
66
22.8
Yes, and it was not severe
130
45.0
Place of treatment for children above 9 months
Buy drugs from pharmacy
79
27.3
Hospital
155
53.6
Manage symptomatically
55
19.0
Receipt of information on malaria vaccine from county
Yes
274
94.8
No
15
5.2
About gender, a high proportion of the participants; 209 (72.3%) were females, with a high percentage of them
106 (36.7%) reporting to have certificate as the highest level of education. In line with marital status, slightly
more than average; 151 (52.2%) were married. Slightly more than a quarter of the participants; 75 (26.0%)
reported that farming was their main source of income
Uptake of Third and Fourth Doses
Regarding the uptake of malaria vaccine, an average; 147 (50.9%) had received the third dose of malaria
vaccine whereas a paltry; 30 (10.4%) had received the fourth dose of malaria vaccine as shown in figure 1. A
few key informants said the uptake has excitement after birth, which then slows down; This may be attributed
to overwhelmed and unfriendly staff and stocks outages at health facilities offering immunization. KII
Muhoroni Subcounty Community Focal Person
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Figure 1. Uptake of Third and Fourth Doses
Factors Associated with Third Dose Uptake
Chi-square analysis indicated that the highest level of education was significantly associated with uptake of the
third dose (χ²=8.331, df=3, p=0.040). Gender, marital status, and income source were not statistically
significant. Logistic regression showed that caregivers with a bachelor’s degree had 1.3 times higher odds of
third dose uptake compared to those with no formal education (OR=1.27; 95% CI: 0.56–2.89; p=0.043) (Table
2).
Table 2. Association between socio-demographic factors and uptake of third dose of malaria vaccine
Variables
χ
2
p-value
Socio-demographic characteristic
Yes n (%)
No n (%)
Male
35 (12.1)
45 (15.6)
2.241
0.086
Female
112 (38.8)
97(33.6)
Highest level of education
Bachelors’ degree
17 (5.9)
17 (5.9)
8.331
0.040*
Certificate
48 (16.6)
58 (20.1)
Diploma
52 (18.0)
29 (10.0)
No formal education
30 (10.4)
38 (13.1)
Marital status
Divorced
13 (4.5)
9 (3.1)
6.177
0.186
Married
83 (28.7)
68 (23.5)
Separated
9 (3.1)
11 (3.8)
Single
24 (8.3)
39 (13.5)
Widowed
18 (6.2)
15 (5.2)
50.90%
10.40%
49.10%
89.60%
0.00% 20.00% 40.00% 60.00% 80.00% 100.00%
Third Dose
Fourth Dose
Uptake of Third and Fourth Malaria Vaccine
No Yes
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Income source
Farming
42 (14.5)
33 (11.4)
6.286
0.179
Formal employment
30 (10.4)
38 (13.1)
Informal employment
19 (6.6)
18 (6.2)
Large scale business
23 (8.0)
12 (4.2)
Small scale business
33 (11.4)
14.2)
Factors Associated with Fourth Dose Uptake
Participant’s gender was significantly associated with uptake of fourth malaria vaccine (χ2=5.228, df=1,
p=0.022, CI=95%). In addition, highest level of education was significantly associated with uptake of fourth
malaria vaccine (χ2=16.556, df=3, p=0.001, CI=95%). Income source was further found to be significantly
associated with uptake of fourth vaccine does (χ2=9.834, df=4, p=0.043, CI=95%). However, marital status
did not demonstrate significant associations with uptake of fourth dose of malaria vaccine (p=0.341) as shown
in Table 3
Table 3. Association between socio-demographic factors and uptake of fourth dose of malaria vaccine
Variables
Uptake of Fourth Dose
χ
2
p-value
Yes n (%)
No n (%)
Socio-demographic characteristic
Male
3 (1.0)
77 (26.6)
5.228
0.022*
Female
27 (9.3)
182 (63.0)
Highest level of education
Bachelors’ degree
4 (1.4)
30 (10.4)
16.556
0.001*
Certificate
3 (1.0)
103 (35.6)
Diploma
8 (2.8)
73 (25.3)
No formal education
15 (5.2)
53 (18.3)
Marital status
Divorced
1 (0.3)
21 (7.3)
4.513
0.341
Married
21 (7.3)
130 (45.0)
Separated
1 (0.3)
19 (6.6)
Single
5 (1.7)
58 (20.1)
Widowed
2 (0.7)
31 (10.7)
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Income source
Farming
11 (3.8)
64 (22.1)
9.834
0.043*
Formal employment
8 (2.8)
60 (20.8)
Informal employment
7 (2.4)
30 (10.4)
Large scale business
1 (0.3)
34 (11.8)
Small scale business
3 (1.0)
71 (24.6)
Logistic regression analysis showed that gender influenced uptake of fourth dose of malaria vaccine by 5 times
(OR=4.647, 95% CI=1.305-16.543, p=0.018). Logistic regression analysis showed that education level did not
have a significant influence on uptake of fourth dose of malaria vaccine (OR=0.522, 95% CI=0.119-2.289,
p=0.388). Similarly, main source of income level did not have a significant influence on uptake of fourth dose
of malaria vaccine (OR=3.499, 95% CI=0.874-14.011, p=0.077).
Qualitative Findings
The key informants also described the third and fourth uptake is erratic. This is confirmed by the quantitative
data. According to the key informants, the high uptake of initial doses may be due to many factors, including
convenient schedule with the other vaccines in the KEPI schedule, effective public mobilization and education
through the community strategy(CHPs) , accessibility of the vaccine as it was offered in all the health
facilities, availability of the vaccine, and the high morbidity and mortality of the children due to malaria that
made the caregivers count on the new intervention. “…The initial doses are considered by the caregivers as
important, and they are timed at crucial months when the child is vulnerable and is still a priority to the mother
and visits the health facility regularly for other services. The caregiver does not need to make a trip just for the
malaria vaccine, but for other child wellness clinic (CWC) services.…”
DISCUSSION
This study investigated socio-demographic factors influencing the uptake of the third and fourth doses of the
RTS, S/AS01E malaria vaccine in Muhoroni Sub-County, Kenya. The findings reveal a substantial drop in
vaccine coverage from the third to the fourth dose, consistent with national and regional patterns (Moturi et al.,
2023; Okanda et al., 2023).
Interpretation of Key Findings
The uptake of the third dose (50.9%) and especially the fourth dose (10.4%) falls significantly short of the
WHO target of 90% for complete malaria vaccination. Higher caregiver education was associated with
increased likelihood of third dose uptake, echoing previous research linking education to vaccine literacy,
understanding of disease prevention, and health service utilization (Kempter & Upadhayay, 2022;
Chukwuocha et al., 2018).
For the fourth dose, gender, education, and income were significantly associated in bivariate analysis, although
only gender remained significant after adjustment. This suggests that female caregivers may be more
committed to ensuring completion of the vaccination schedule, potentially due to their primary role in child
healthcare, a finding supported by studies in similar African settings (Ateke et al., 2024; Yeboah et al., 2022).
Barriers to Vaccine Completion
Qualitative findings identified several barriers: vaccine fatigue, competing household responsibilities,
perceived side effects, unfriendly health worker attitudes, and occasional stock-outs. These factors mirror those
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reported in Western Kenya and other malaria-endemic regions (Hill et al., 2024; Hoyt et al., 2023). The
alignment of early vaccine doses with other routine immunizations may partially explain higher initial uptake,
while the 24-month schedule for the fourth dose, often requiring a separate visit, contributes to attrition.
Comparison with Existing Literature
The observed dose completion gap aligns with the Health Belief Model and Social Cognitive Theory, which
highlight how perceived benefits, barriers, and cues to action influence health behaviours (Rosenstock et al.,
1988; Strecher & Rosenstock, 1997). Trust in the healthcare system, convenience of services, and accurate
information emerge as critical determinants of vaccine adherence. Similar multi-factorial barriers have been
reported in Ghana, Cameroon, and Nigeria, underscoring the need for locally adapted strategies (Grant et al.,
2022; Asmare, 2022; Ojakaa et al., 2014).
Implications for Practice and Policy
Improving completion rates for the RTS, S/AS01E malaria vaccine in Muhoroni Sub-County requires a
combination of community engagement, health system strengthening, and targeted follow-up. Community-
driven awareness campaigns led by trusted leaders, including religious and cultural influencers, can help
address misinformation, cultural barriers, and misconceptions about vaccine safety and necessity.
Strengthening the health system to ensure consistent vaccine availability, reducing waiting times, and
enhancing the friendliness of service delivery will improve caregiver satisfaction and encourage return visits
for subsequent doses. Integrating the later malaria vaccine doses with other child health services, such as
growth monitoring or deworming, can reduce the burden of additional clinic visits and help sustain adherence.
Furthermore, targeted follow-up of households at higher risk of default—particularly those with lower
education or income levels—through home visits, reminder systems, or transport support may close the gap in
late-dose uptake. These combined strategies can address both demand- and supply-side barriers, ultimately
improving vaccine completion rates and contributing to sustained malaria control in high-transmission settings.
Strengths and Limitations
The study’s strengths include a sub-county-wide sampling frame, 100% response rate, and the use of mixed
methods, which allowed triangulation of quantitative and qualitative data. However, the cross-sectional design
limits causal inference, and self-reported data may be affected by recall or social desirability bias. Findings
may not be generalizable beyond similar rural, high-transmission settings.
CONCLUSION
This study demonstrates that uptake of the third and fourth doses of the RTS, S/AS01E malaria vaccine in
Muhoroni Sub-County remains well below the WHO target of 90%. Education level, gender, income source,
and access to health facilities were key factors influencing uptake, while cultural beliefs, vaccine fatigue,
competing responsibilities, and stock-outs emerged as significant barriers. These findings highlight the need
for targeted interventions that combine community-driven awareness campaigns, culturally sensitive health
education, integration of later doses with other child health services, and system-level improvements to ensure
consistent vaccine availability. Addressing both demand- and supply-side challenges will be essential to
improving vaccine completion rates, maximizing the protective benefits of the RTS, S/AS01E vaccine, and
reducing malaria-related morbidity and mortality among children in high-transmission settings.
RECOMMENDATIONS
Based on the study findings, the following recommendations are crucial to enhance the uptake of the third and
fourth doses of Malaria vaccine:
Due to the 3rd and 4
th
vaccine dose not meeting WHO uptake target, action from all stakeholders
implementing the malaria vaccine in Muhoroni Subcounty is required to intensify the uptake in the rolling out
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the malaria vaccination programs in this area with specific focus to strategies which can accelerate the fourth
dose uptake. The intervention needs to take into context the demographic factors
ACKNOWLEDGEMENT
I am profoundly grateful to Maseno University, School of Public Health and Community Development, for the
academic environment and institutional support that made this work possible. I extend my deepest appreciation
to my supervisors, Dr. Doreen Othero and Prof. Collins Ouma, for their insightful guidance, meticulous
reviews, and unwavering encouragement throughout every stage of this study.
I thank the Kisumu County Department of Health, the management and staff of Muhoroni Sub-County
Hospital, and the Community Health Promoters (CHPs) for their collaboration, facilitation, and logistical
support in the field. I am especially indebted to the caregivers of children under five who participated in this
research; your time, openness, and trust were indispensable to the generation of these findings.
Ethical and regulatory approvals and permissions are gratefully acknowledged from the Great Lakes
University of Kisumu Scientific and Ethics Review Committee (GLUSERC), the National Commission for
Science, Technology and Innovation (NACOSTI), and the relevant administrative authorities. I also appreciate
the dedication of my research assistants, whose professionalism and care ensured high-quality data collection.
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