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 Table of Contents  
Year : 2023  |  Volume : 4  |  Issue : 1  |  Page : 36-41

Age-appropriate vaccination and its determinants among children <24 months in Kano, Nigeria

1 Department of Community Medicine, Aminu Kano Teaching Hospital, Kano, Nigeria
2 Department of Community Medicine, Aminu Kano Teaching Hospital; Department of Community Medicine, Bayero University Kano, Nigeria
3 Department of Community Medicine, Abubakar Tafawa Balewa University, Bauchi, Nigeria
4 Department of Community Medicine, University of Maiduguri Teaching Hospital, Maiduguri, Nigeria

Date of Submission06-Apr-2022
Date of Decision18-May-2022
Date of Acceptance28-May-2022
Date of Web Publication15-Feb-2023

Correspondence Address:
Dr. Fatimah Isma'il Tsiga-Ahmed
Department of Community Medicine, College of Health Sciences, Aminu Kano Teaching Hospital and Bayero University Kano, Kano
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jphpc.jphpc_13_22

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Background: Administration of vaccines at recommended ages and according to recommended intervals between doses of multi-dose antigens provides optimal protection, ultimately reducing the possibility of propagating the transmission of vaccine-preventable diseases. A sizable discrepancy in the median age at vaccination has been shown in Nigeria. This study assessed age-appropriate vaccination and related factors among children aged 0–23 months attending immunization clinics in the Kano metropolis. Materials and Methods: An adapted and pretested semi-structured interviewer-administered questionnaire was used to obtain information from a cross-section of 384 pairs of mothers/babies who presented to the immunization clinics of selected primary health centers within Kano metropolis. Results: The median ages at vaccination were 13, 49, 91, 122, and 282 days for BCG, pentavalent-1, pentavalent-2, pentavalent-3, and measles antigens, respectively. Proportions of children who had received age-appropriate vaccines were 83.8%, 81.6%, 64.9%, 60.4%, and 40.3% for BCG, pentavalent-1, pentavalent-2, pentavalent-3, and measles vaccinations, respectively. Children who were 4 months or older were 80% less likely to be age-appropriately vaccinated compared to those 3 months or younger (adjusted odds ratios [aOR]: 0.2, 95% confidence interval [CI]: 0.1–0.7). Furthermore, children with a previous experience of an adverse event following immunization were 50% less likely to be age-appropriate for the index vaccination (aOR: 0.5, 95% CI: 0.3–0.9). Conclusion: Many children in the Kano metropolis were not age-appropriately vaccinated. The measles vaccine had the least proportion of age-appropriately vaccinated children. Sensitization and health education of caregivers on timely vaccination cannot be overemphasized.

Keywords: Age-appropriate, children, determinants, Kano, vaccination

How to cite this article:
Maizare HI, Tsiga-Ahmed FI, Faruk SL, Ahmad AY, Abulfathi AA. Age-appropriate vaccination and its determinants among children <24 months in Kano, Nigeria. J Public Health Prim Care 2023;4:36-41

How to cite this URL:
Maizare HI, Tsiga-Ahmed FI, Faruk SL, Ahmad AY, Abulfathi AA. Age-appropriate vaccination and its determinants among children <24 months in Kano, Nigeria. J Public Health Prim Care [serial online] 2023 [cited 2023 Jun 5];4:36-41. Available from: http://www.jphpc.org/text.asp?2023/4/1/36/369661

  Introduction Top

The World Health Organization (WHO) has declared that approximately 1.5 million deaths among children aged 1–59 months are vaccine-preventable.[1],[2],[3] Developments in vaccines have contributed to a decline in the incidence, disability, and death from vaccine-preventable diseases worldwide.[4],[5] As a result of this, about 4–5 million lives have been saved with significant impacts on the health of individuals, communities, and nations.[6]

According to the WHO's Expanded Program on Immunization schedule, children are age-appropriately vaccinated if they have received all vaccines for their age.[6],[7] Therefore, childhood vaccines must be administered at the recommended ages and intervals to achieve optimum protection against vaccine-preventable diseases. Timeliness could be early, timely, or late.[6],[8] Reducing the timing intervals between doses of vaccines may hamper the body's antibody response.[2],[8],[9] Increasing vaccine timing, on the other hand, could result in the pooling of children with incomplete vaccination status, ultimately leading to increased disease susceptibility and epidemics when a vaccine-preventable illness is introduced into a community.[2] Major risk factors for delay in age-appropriate vaccination relate to vaccination practices, logistics of providing vaccines, perceived contraindications, beliefs and attitudes toward vaccines, and socioeconomic determinants.[2],[8],[10]

Studies have shown that few children received all recommended vaccine doses on time, even with high up-to-date coverage.[2],[9],[11],[12] A study, which analyzed the timeliness of vaccination in 31 Countries, reported significant vaccination delays, with a median of 41% for timely DPT3, despite reasonably high vaccination coverage.[6] Another study from Pakistan reported an OPV3 completion rate of 80.3% with an OPV1 to an OPV3 dropout rate of 7.7% compared with DTP3 completion of 55.9%, DTP1 to a DTP3 dropout rate of 14% and completion rate for measles was 62.5%.[7] Late immunizations occurred in 65.5% for third doses of the OPV and DTP series, early (21.9%) for measles vaccine. Timely immunization of DPT1 helped ensure timeliness for DPT2, and DPT3.[8] BCG immunization was timely in 70.1% of children compared with 77.1% for OPV0, 48.0% of OPV1 immunization were timely as compared with 36.4% of OPV2 and 27.4% of OPV3. For DPT 1 immunization, 49.0% were timely for DPT 1 as compared with 35.5% for DPT 2, and 27.4% for DPT 3.[8]

In sub-Saharan African countries, substantial delay in timely vaccination receipt has been reported. Although 82.3% of infants aged 3–12-months-old received all recommended vaccines in Ethiopia, only 55.9% of these vaccinations were timely.[12] From Uganda, it was reported that 45.6% of the 10–23 months old children surveyed received all vaccines within the recommended time ranges. Timely receipt of vaccinations was highest for the BCG vaccine (92.7%), and lowest for measles (67.5%) and 10.7% of the measles vaccinations were administered earlier than the recommended time.[13] A similar study from Ghana reported that vaccine uptake was generally timely for earlier antigens; 87.3% of vaccines were received on time, with only 5.3% of vaccines received after 28 days of the recommended date.[2]

From southern Nigeria, it was reported that 67.3% of children received their pentavalent vaccine promptly, while only 40% received measles and yellow fever vaccines on time.[11] Another study from a similar setting in Nigeria observed that children presented late for the first vaccine, with over a third appearing after 4 weeks of life.[8] From Jos, North-central Nigeria, Approximately 53.8% of newborns received at-birth vaccination within 24 h of life.[14]

An efficient and thorough immunization program in which vaccines are timely administered can prevent childhood diseases and save many lives, particularly in Northern Nigeria, where child health indicators are not encouraging. This study sought to assess age-appropriate vaccination and its determinants among children <24 months in Kano, Nigeria.

  Materials and Methods Top

Study area and population

This study was conducted within Kano's metropolitan Local Government Areas (LGAs) in northern Nigeria. The estimated population of Kano in 2021 was 14,065,260, with about 2,813,052 children under 5 years of age. The study population included caregivers of children <24 months attending immunization clinics of selected Primary Health Centers (PHCs) and their babies. Babies presenting for the first vaccine and those with no immunization card were excluded.

Study design and sampling

This was a hospital-based, descriptive cross-sectional study. Using the formula for calculating single proportions,[15] we estimated that a minimum sample size of 301 will allow us to determine the prevalence of infants who were timely for vaccination in Kano, within 8% precision of 53.8% (a value obtained from northern Nigeria),[14] α = 0.05 and 80% power. This was increased by 10% to account for nonresponse, finally giving a sample of 332.

A three-stage sampling technique was used to select eligible respondents. The first stage involved the selection of four out of the eight metropolitan LGAs via balloting. Two PHCs were then randomly selected out of the four selected LGAs. Respondents were then selected by systematic sampling at each PHC. All eligible respondents who were present on the available days of data collection were subsequently included in the study.

Measures and data collection

Data were collected from eligible respondents using a pretested structured interviewer-administered questionnaire adapted from a previous study.[7] Information on age, age at the commencement of vaccination, and the date of receipt of various vaccines were retrieved from the immunization cards. Age at receipt of vaccination was calculated in days using the dates of birth and the dates of vaccines. The period until a child received a vaccine dose was calculated by subtracting the birth date from the date of vaccination.

Children were considered age-appropriately vaccinated if they received all vaccines according to the time recommended by WHO's Expanded Programme on the Immunization schedule, with timeliness categorized as early, timely or late. According to the Nigerian schedule, BCG is given at birth but considered timely if given within 0–28 days, pentavalent-1 is given at 6 weeks (42 days) but timely if given between 39 and 70 days, pentavalent-2 is recommended at 10 weeks (70 days) but timely between 67 and 98 days, pentavalent-3 at 14 weeks (98 days) but timely if given 95–126 days and measles is recommended at 39 weeks (273 days) but timely if given between 270 and 301 days.

A vaccine was considered early if received earlier than the recommended dates and late if received later than the recommended dates.

Statistical analysis

Data were coded and entered into a spreadsheet on Microsoft Excel and analyzed using SPSS version 22 (IBM Corp., Armonk, NY, USA). Numerical variables were summarized and presented using mean and standard deviation (SD) or median and interquartile range (IQR). The categorical variables were summarized using frequencies and percentages. Pearson's Chi-square or Fisher's exact test as appropriate was used to assess the association between sociodemographic variables and being age-appropriately vaccinated. Type I error was fixed at 5% for all tests. Binary logistic regression models were developed for age-appropriate immunization. Independent variables with P < 0.10 at the bivariate level were included in the logistic regression model. The mother's age and education were considered a priori confounding variables. Adjusted odds ratios (aORs) and their 95% confidence intervals (CIs) were used to measure the strength and direction of the effect of determinants.

Ethical considerations

The Kano State Ministry of Health research ethics committee reviewed and approved the study protocol (Reference-MOH/OFF/797/T. I/1168). Participants were informed about the study objectives and that involvement was entirely voluntary.

All provisions of the Helsinki declaration were adhered to.

  Results Top

A total of 377 mother/baby pairs participated in the study. The age of the index child ranged from 1.5-15 months, with a mean and SD of 4.4 ± 2.8 months. Almost half of the children (49.3%, n = 186) were <3 months of age, and 52.9% (n = 201) were males. About three-quarters (75.9%, n = 286) were delivered in the hospital, and approximately one-third were of the second birth order (32.9%, n = 124). The majority of the children (97.6%, n = 368) were apparently healthy when they presented for immunization. The mothers' age ranged from 15 to 50 years, with a mean and SD of 26.4 ± 6.0 years. Over two-thirds of the respondents were of the Hausa ethnic group (63.7%, n = 240), and almost all were married (98.4%, n = 371). More than half of the respondents (61.5%, n = 232) were educated up to secondary school and 34.2% of the respondents (n = 129) had four or more children alive [Table 1].
Table 1: Sociodemographic characteristics of index children and their mothers

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Age-appropriate vaccination

The median ages at vaccination for the respondents were 13 days IQR: 8, 21 for BCG, 50 days (IQR: 43,62) for pentavalent-1, 86 days (IQR: 75,103) for pentavalent-2, 118 days (IQR: 105,136) for pentavalent-3 and 282 days (IQR: 262,304) for measles [Figure 1]. Based on the index visit, 7.7% (n = 29) were early, 63.4% (n = 239) were timely, 28.9% (n = 109) were late for the recommended vaccine.
Figure 1: Median ages at vaccination among respondents

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[Table 2] shows the various proportions of respondents based on categories of timeliness. The majority (83.8%, n = 315) of infants were age-appropriately vaccinated for BCG. Precisely 81.6% (n = 307), 64.9% (n = 178), 60.4% (n = 90), and 40.3% (n = 23) were appropriately vaccinated for pentavalent-1, pentavalent-2, pentavalent-3, and measles antigens, respectively. Approximately a third of the respondents were late for pentavalent-3 (3.1%, n = 52) and a similar proportion were early for measles (31.6%, n = 18) vaccines. Pentavalent-1 had the least proportion of respondents who were late (13.3%, n = 50) and pentavalent-2 had the minimum number who were early for receipt of vaccine (4.7%, n = 7).
Table 2: Age-appropriate vaccination among respondents

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Bivariate analyses revealed a relationship between age-appropriate vaccination and age of the child, index visit, birth order, and a previous history of adverse events following immunization (AEFI). However, on multivariate analysis, the relationship only persisted for the child's age and prior history of adverse events following vaccination. Children who were 7 months or more were 80% less likely to be age-appropriately vaccinated compared to those 3 months or younger (aOR: 0.2, 95% CI: 0.1–0.7). Similarly, children with a previous history of AEFI were 50% less likely to be age-appropriately vaccinated compared to those with no history (aOR: 1.9, 95% CI: 1.2–3.4) [Table 3].
Table 3: Multivariable logistic regression for determinants of age-appropriate vaccination among index children, Kano, Nigeria (n=377)

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  Discussion Top

We assessed age-appropriate vaccination and its determinants among children <24 months in Kano, Northern Nigeria. We found that at the index visit, about a third were late for receipt of the recommended vaccine. Nearly 8 in 10 children were age-appropriately vaccinated for BCG and pentavalent-1, approximately 6 in 10 for pentavalent-2 and pentavalent-3 and only 4 in 10 were age-appropriately vaccinated for measles. Age-appropriate vaccination at the index visit was predicted by the child's age and a prior history of an AEFI.

Similar to our findings, delays have been reported in receiving routine childhood immunizations within Nigeria and across the globe.[2],[7],[16],[17] About a third of children from Southern Nigeria presented for their first vaccine after 4 weeks of life.[7] In Saudi Arabia, 23% of children surveyed had delayed vaccinations for more than 4 weeks,[16] a figure lower than ours but much higher than 5.3%, a value obtained from a neighboring African country.[2] While delays in receipt of vaccinations have been aligned to service and client-related reasons, contextual differences are bound to influence these factors. For instance, cultural beliefs that have hindered the vaccination process in the northern part of the country may contribute to the delays in receiving these vaccines.

Our study revealed that BCG was the most timely vaccine. At the same time, measles was the least timely received vaccine, similar to what was found from studies conducted in Benin, southern Nigeria,[7] and Uganda.[13] Nonetheless, our findings contrast revelations from Cameroun where measles was administered in a more timely fashion compared to BCG.[18] The prompt receipt of BCG in this study might be explained by the fact that three-quarters of the children in this study were delivered in a health facility. Delivery in a health facility has been shown to improve the timeliness of hepatitis B birth dose, a vaccine given alongside the BCG.[19] In Nigeria, it is expected that children born in the hospital should receive the first vaccine before discharge.

Measles had the highest number of children who were immunized before the recommended schedule of nine months. The Nigerian national guideline for response to measles outbreaks in Nigeria recommends an “Outbreak Response Immunization” during measles outbreaks. In addition to other things, this involves vaccinating all children 6 − 59 months who present to health facilities in the affected places.[20] In recent years, there have been measles outbreaks in the different parts of Northern Nigeria, a reason why some children would have received the measles antigen before the recommended age.

This study discovered a decreased likelihood of being age-appropriately vaccinated with the advancing age of the child, similar to the results from a Lebanese study.[21] This finding may not be unrelated to the lower proportion of age-appropriately vaccinated children among the later vaccines. Forgetfulness and the view of reduced relevance of later visits as well as engagement of mothers at workplaces have been possible explanations proffered for this finding.[2] Similarly, we realized that a previous history of AEFI among the respondents predisposed participants to being inappropriately vaccinated for age. An untoward experience with a vaccine can cause a delay or hesitation toward receipt of the subsequent doses of the vaccine. Parental concerns about AEFIs have been recurring reasons for vaccine hesitancy in children.[22]


The findings from this study must be viewed within the realms of its strengths and limitations. One such limitation is the study's cross-sectional design; results showing a relationship between the variables do not denote causality. In addition, selecting participants from the facility does not eliminate selection bias. However, the selection of respondents from different health centres will ensure less variability and improve generalizability.

  Conclusion Top

The study reported a high proportion of age-inappropriate vaccinations with a steady decline in receiving age-appropriate vaccines from BCG to measles. Increasing age and a prior history of AEFI in the child were found to be risk factors for age-inappropriate vaccination.

Routine vaccination timeliness and completeness are still public health challenges. We recommend the sensitization, advocacies and health education of caregivers, traditional and religious leaders on the importance of age-appropriate vaccination. There is a need to include the age-appropriateness of immunization as an indicator of vaccination program performance. Qualitative research to explore the causes of age-inappropriate vaccination should be considered.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

World Health Organization (WHO). Immunization. World Health Organization (WHO) Fact Sheets; 2019. Available from: https://www.who.int/news-room/facts-in-pictures/detail/immunization. [Last accessed on 2020 Jul 05].  Back to cited text no. 1
Laryea DO, Abbeyquaye Parbie E, Frimpong E. Timeliness of childhood vaccine uptake among children attending a tertiary health service facility-based immunisation clinic in Ghana. BMC Public Health 2014;14:90.  Back to cited text no. 2
World Health Organization. WHO vaccine-preventable diseases: monitoring system. 2020 global summary. 2020. Geneva, Switzerland: World Health Organization. 2020.  Back to cited text no. 3
Di Pasquale A, Bonanni P, Garçon N, Stanberry LR, El-Hodhod M, Tavares Da Silva F. Vaccine safety evaluation: Practical aspects in assessing benefits and risks. Vaccine 2016;34:6672-80.  Back to cited text no. 4
WHO. Vaccine-Preventable Diseases and Vaccines-2017 Update. International Travel and Health. WHO; 2012. p. 1-63.  Back to cited text no. 5
Rauniyar SK, Munkhbat E, Ueda P, Yoneoka D, Shibuya K, Nomura S. Timeliness of routine vaccination among children and determinants associated with age-appropriate vaccination in Mongolia. Heliyon 2020;6:e04898.  Back to cited text no. 6
Sadoh AE, Eregie CO. Timeliness and completion rate of immunization among Nigerian children attending a clinic-based immunization service. J Health Popul Nutr 2009;27:391-5.  Back to cited text no. 7
Zaidi SM, Khowaja S, Kumar Dharma V, Khan AJ, Chandir S. Coverage, timeliness, and determinants of immunization completion in Pakistan: Evidence from the Demographic and Health Survey (2006-07). Hum Vaccin Immunother 2014;10:1712-20.  Back to cited text no. 8
Bassoum O, Kimura M, Tal Dia A, Lemoine M, Shimakawa Y. Coverage and timeliness of birth dose vaccination in Sub-Saharan Africa: A systematic review and meta-analysis. Vaccines (Basel) 2020;8:E301.  Back to cited text no. 9
Hu Y, Chen Y, Guo J, Tang X, Shen L. Completeness and timeliness of vaccination and determinants for low and late uptake among young children in eastern China. Hum Vaccin Immunother 2014;10:1408-15.  Back to cited text no. 10
Jc N, Maduka O. Completeness and timeliness of immunization among children aged 12 to 23 months in South-South Nigeria. J Community Med Prim Heal Care 2019;31:22-31.  Back to cited text no. 11
Masters NB, Tefera YA, Wagner AL, Boulton ML. Vaccine hesitancy among caregivers and association with childhood vaccination timeliness in Addis Ababa, Ethiopia. Hum Vaccin Immunother 2018;14:2340-7.  Back to cited text no. 12
Babirye JN, Engebretsen IM, Makumbi F, Fadnes LT, Wamani H, Tylleskar T, et al. Timeliness of childhood vaccinations in Kampala Uganda: A community-based cross-sectional study. PLoS One 2012;7:e35432.  Back to cited text no. 13
Danjuma SD, Ibrahim AI, Shehu NY, Diala MU, Pam CV, Ogbodo CO. At-birth vaccination timeliness: An analysis of inborns in the highlands of Jos, North-Central Nigeria. Niger Postgrad Med J 2020;27:209-14.  Back to cited text no. 14
[PUBMED]  [Full text]  
Ajay S, Micah M. Sampling technique and determination of sample size in applied statistics research: An overview. Int J Econ Commer Manag United Kingdom 2014;2:32-3.  Back to cited text no. 15
Alrowaili GZ, Dar UF, Bandy AH. May we improve vaccine timeliness among children? A cross sectional survey in northern Saudi Arabia. J Family Community Med 2019;26:113-7.  Back to cited text no. 16
Riise ØR, Laake I, Bergsaker MA. Nøkleby H, Haugen IL, Storsæter J. Monitoring of timely and delayed vaccinations: A nation-wide registry-based study of Norwegian children aged <2 years. BMC Pediatr 2015;15:180.  Back to cited text no. 17
Chiabi A, Nguefack FD, Njapndounke F, Kobela M, Kenfack K, Nguefack S, et al. Vaccination of infants aged 0 to 11 months at the Yaounde Gynaeco-obstetric and pediatric hospital in Cameroon: How complete and how timely? BMC Pediatr 2017;17:206.  Back to cited text no. 18
Mansour Z, Said R, Brandt L, Khachan J, Rady A, Fahmy K, et al. Factors affecting age-appropriate timeliness of vaccination coverage among children in Lebanon. Gates Open Res 2018;2:71.  Back to cited text no. 19
Isere EE, Fatiregun AA. Measles case-based surveillance and outbreak response in Nigeria; an update for clinicians and public health professionals. Ann Ib Postgrad Med 2014;12:15-21.  Back to cited text no. 20
Noh JW, Kim YM, Akram N, Yoo KB, Cheon J, Lee LJ, et al. Determinants of timeliness in early childhood vaccination among mothers with vaccination cards in Sindh province, Pakistan: A secondary analysis of cross-sectional survey data. BMJ Open 2019;9:e028922.  Back to cited text no. 21
Sankaranarayanan S, Jayaraman A, Gopichandran V. Assessment of vaccine hesitancy among parents of children between 1 and 5 years of age at a tertiary care hospital in Chennai. Indian J Community Med 2019;44:394-6.  Back to cited text no. 22
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