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Vaccination of infants aged 0 to 11 months at the Yaounde Gynaeco-obstetric and pediatric hospital in Cameroon: how complete and how timely?

  • 1, 2Email author,
  • 1, 2,
  • 2,
  • 2,
  • 3,
  • 1, 2,
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BMC PediatricsBMC series – open, inclusive and trusted201717:206

https://doi.org/10.1186/s12887-017-0954-1

  • Received: 7 June 2017
  • Accepted: 24 November 2017
  • Published:
Open Peer Review reports

Abstract

Background

Vaccination is a major, but simple and cost effective public health intervention in the prevention of infectious diseases, especially in children. Nowadays, many children still miss scheduled vaccines in the Extended Program of Immunization (EPI) or are being vaccinated after the recommended ages.This study was aimed at assessing vaccination completeness and timeliness in children aged 0 to 11 months attending the vaccination clinic of the Yaounde Gynaeco-Obstetric and Pediatric Hospital.

Methods

This was an observational cross-sectional study over a period of 3 months (1st February to 30th April 2016). 400 mothers were interviewed and their children’s vaccination booklets analyzed. Information on the children and the parents was collected using a pretested questionnaire. Data analysis was done using SPSS version 20 software. Bivariate and multivariate analysis with logistic regression was done to assess the determinants of completeness and timeliness.

Results

A total of 400 mother-infant pairs were sampled. The vaccination completeness rate was 96.3%. This rate varied between 99.50% for BCG and 94.36% for IPV. Most of the children were born at the Yaounde Gynaeco-Obstetric and Pediatric hospital where they were regularly receiving their vaccines. The proportion of correctly vaccinated infants was 73.3%. The most differed vaccines were BCG, PCV13 and IPV. Factors influencing immunization completeness were the father’s profession and the mother’s level of education.

Conclusions

Despite the high immunization coverage, some children did not complete their EPI vaccines and many of them took at least one vaccine after the recommended age.

Keywords

  • Immunization timeliness
  • Immunization completeness
  • Expanded programme of immunization

Background

Vaccination is considered as one of the biggest achievements of the twentieth century and as one of the most cost effective measures in the prevention of childhood diseases [1]. In 1974, the World Health Organization (WHO) launched a worldwide vaccination program known as the Expanded Program of Immunization (EPI), which has been considered one of the major public health interventions aimed at reducing infant morbidity and mortality [2]. During the launching of the EPI in 1976, only about 5% of infants throughout the world were protected against six diseases (diphteria, measles, pertussis, poliomyelitis, tetanus, and tuberculosis). By 2013, the number of protected infants was more than 80% in many countries. It is estimated that vaccination helps to prevent 2 to 3 million infant deaths each year [3].

The Expanded Program of Immunization started in Cameroon in 1976 as a pilot project and targeted infants from 0 to 11 months. Initially it targeted 6 diseases (diphtheria, measles, pertussis, poliomyelitis, tetanus, and tuberculosis), and other vaccines were gradually introduced; the last to be introduced in the EPI was IPV in 2015. Presently, it has vaccines against the following diseases: tuberculosis, diphteria, tetanus, poliomyelitis, pertussis, viral hepatitis B, type b Hemophilus influenza infections, pneumococcal infections, diarrhoea caused by rotavirus, measles, yellow fever, and rubeola. An infant is completely immunized when he or she has received all the vaccines in the EPI. Ensuring that all the doses are not only administered, but given at the appropriate ages, is of crucial importance in ensuring the efficacy of the vaccine in disease prevention [4]. An infant is correctly vaccinated when he or she has received all the vaccines at the recommended ages. Many infants still do not complete their vaccination schedules or are vaccinated after the recommended ages [5, 6].

Given the importance of vaccination in reducing morbidity and mortality in children, we decided to assess the completeness and timeliness of immunization and its determinants at the Yaounde Gyneco-Obstetric and Pediatric hospital, which is a tertiary mother and child hospital in Cameroon. This will ultimately improve the vaccine coverage and reduce obstacles which might hinder effective implementation.

Methods

A cross-sectional analytical study was conducted; over a period of 3 months (1st February to 30th April 2016) in the vaccination unit of the Yaounde Gyneco-Obstetric and Pediatric Hospital (YGOPH), which is a mother and child referral hospital in Yaounde, the capital city of Cameroon. All mothers of infants aged 0 to 11 months coming for routine EPI were enrolled in the study.

Pre-tested questionnaires were filled for all mother-infant pairs at the vaccination unit, after obtaining consent from the mothers or caretakers of the infants (see Additional file 1). Information collected on the infants included age, sex, place of birth, place of first vaccination, the usual vaccination site, vaccines received, and date of vaccination for each antigen received.

Information concerning the parents included: age, level of education, profession, marital status, religion, region of origin, distance from the house to the vaccination unit, satisfaction from vaccination unit as expressed by the mothers or caretakers. The cut offs of 30 years for the mothers’ age and a distance of 5 km, was used in our analysis; same cut offs were used by Hu et al. [6]. The mothers or the caretakers of the infants were first interviewed and then the vaccination booklets of the infants they came with examined (to minimize recall bias); to verify the vaccines received and the dates they were administered.

The sample size (N) was determined using the formula: \( \frac{{\mathrm{z}}^2\mathrm{p}\;\left(1-\mathrm{p}\right)}{{\mathrm{d}}^2} \)

where z is the significance threshold;1.96 for a 95% confidence level, d is the error margin; 5%, and p; 64.3%, is the prevalence of vaccine completeness from the study of Ba Pouth et al. [5] in the Djoungolo health district in 2012.

Definition of variables

The dependent variables were the immunization completeness, and the antigen specific immunization coverage of children aged 0 to 11 months.

An infant was considered as being completely vaccinated if he/she had received all of the doses of the following vaccines: BCG, OPV0, DTP-HepB1-Hib1, OPV1, Rota1, Pneumo131, DTP-HepB1-Hib2, OPV2, Rota2, Pneumo132, DTC-HepB1-Hib3, OPV3, Pneumo133, Measles, Yellow fever and Rubeola vaccines according to the EPI schedule.

The immunization coverage per antigen was defined by the ratio of infants that received the antigen divided by the total number of infants sampled.

Immunization timeliness was defined as being vaccinated at the recommended ages. A period of 2 weeks was considered above which the vaccine was considered as delayed. Any child with delayed administration of one or more antigens was considered not timely vaccinated.

The independent variables were the different socio-demographic characteristics of our sample population. The outcomes were immunization completeness and timeliness.

Data analysis

Data analysis was done using SPSS version 20.0 for windows. The data input control permitted the minimization of errors. The analysis of factors associated to vaccination completeness was done using the ‘backwards’ model of multivariate logistic regression. Logistic regression was first done to obtain the crude odds ratio for each of these factors with their 95% confidence intervals and their P-values. Thereafter the variables with a p-value <0.2 were all entered in a model of multivariate logistic regression to control the confounding factors and determine which characteristics were independent predictors of the immunization completeness of the child. A p-value <0.05 and an adjusted odds ratio (AOR) with its 95% confidence interval not containing 1.00 was considered significant.

Ethical considerations

Prior to carrying out this study, administrative authorization and ethical clearance was obtained from the Yaounde Gynaeco-Obstetric and Pediatric hospital and the Faculty of Medicine and Biomedical Sciences of the University of Yaounde I respectively. A written consent form was signed by each mother or caretaker who accepted to be enrolled and participate in the study, and for those who could not read and write verbal consent was sought after receiving information on the study. Participants in the study were informed on any missed vaccine and any other information concerning the child’s vaccinations. All infants with vaccinations not up-to -date were vaccinated as recommended.

Results

Socio-demographic characteristics of the study population.

Overall, there were 415 mothers eligible for the study, and 15 were excluded (10 did not consent to participate and 5 did not have vaccination booklets). A total of 400 mother-infant pairs were sampled, of which 203 (51%) were females and 197 (49%) males; giving a sex ratio of 0.97. The median age for the infants was 98 days (range 1 day to 266 days). Most mothers (56.5%) were less than 30 years, 61.3% had secondary education, 79% were married and 50.3% lived at more than 5 km from the vaccination site (see Table 1). Almost all the fathers (94.8%) had at least secondary school education and 38.8% worked in the informal sector (see Table 2).
Table 1

Vaccination schedule for children aged 0–11 months in Cameroon [20]

Contacts

Age

Vaccine

Route of administration

Preventable diseases

1st contact

At birth

BCG

Intradermal

Tuberculosis

OPV 0

Oral

Poliomyelitis

2nd contact

6 weeks

DTP-HepB-Hib 1

Intramuscular

Diphteria, Tetanus,

Pertussis,Infection due to

Haemophilus Influenzae

type b, Hepatitis B

OPV 1

Oral

Poliomyelitis

Pneumo 13–1

(PCV)

Intramuscular

Pneumococcal infections

ROTA 1

Oral

Rotavirus Diarrhoea

3rd contact

10 weeks

DTP-HepB-Hib 2

Intramuscular

Diphteria, Tetanus,

Pertussis,Infection due to

Haemophilus Influenzae

type b, Hepatitis B

OPV 2

Oral

Poliomyelitis

Pneumo 13–2

ROTA 2

Intramuscular

Oral

Pneumococcal infections

Rotavirus Diarrhoea

4th contact

14 weeks

DTP-HepB-Hib 3

Intramuscular

Diphteria, Tetanus,

Pertussis,Infection due to

Haemophilus Influenzae

type b, Hepatitis B

OPV 3

IPV

Oral

Intramuscular

Poliomyelitis

Pneumo 13–3

Intramuscular

Pneumococcal infections

5th contact

6 to 11

months

Vit A

Oral

 

At 9 months

MR

Subcutaneous

Measles, Rubella

YF

Subcutaneous

Yellow fever

Table 2

Socio-demographic characteristics of the parents

 

Variables

Number

Percentage (%)

Mother’s age (years)

< 30

226

56.5

≥ 30

174

43.5

Mother’s level of education

Illiterate

4

1.0

Primary

32

8.0

Secondary

205

61.3

Higher

159

39.8

Mother’s profession

Private

50

12.5

Public servant

59

14.8

Informal

85

21.3

Pupil or student

69

17.3

Unemployed

137

34.3

Matrimonial status

Single

84

21.0

Couple

316

79.0

Religion

Christian

367

91.8

Muslim

31

7.8

Others

2

0.5

Parity

Primipara

145

36.3

Multipara

255

63.8

Distance from home to the vaccination unit (Km)

< 5

199

49.8

≥ 5

201

50.3

Satisfaction with the vaccination unit

Yes

333

83.3

No

67

16.8

Father’s level of education

Illiterate

2

0.5

Primary

19

4.8

Secondary

166

41.5

Higher

213

53.3

Father’s profession

Private

93

23.3

Public servant

116

29.0

Informal

155

38.8

Pupil or student

25

6.3

Unemployed

11

2.8

Immunization completeness

Of the 400 infants, immunization was complete in 96.3% of them. Amongst the infants who had completed their vaccination, 75.0% were born at the YGOPH, 90.0% of them started their vaccinations there and 87.0% regularly received their vaccines there. The immunization coverage for BCG, DTP3, Polio3 and measles were 99.8%, 93.3%, 93.3% and 100% respectively.

Vaccine coverage for each antigen is presented in Table 3, and the rates are greater than 90% for each antigen. The measles and yellow fever vaccines had the highest coverage of 100%.
Table 3

Vaccination coverage and timely administration per antigen

Vaccines

Vaccines received

na(%)

Vaccines received timely

nc(%)

BCG + Polio 0 (Nb = 400)

399 (99.8)

332 (83.2)

Vaccines at 6 weeks (Nb = 366)

360 (98.4)

340 (94.4)

Vaccines at 10 weeks (Nb = 269)

261 (97.0)

249 (95.4)

Vaccines at 14 weeks (Nb = 208)

194 (93.3)

182 (93.8)

anumber of children who received the vaccine

btotal number of children at the age to receive the vaccine

cnumber of children who received the vaccine on time

Vaccines scheduled at 6 weeks = DTP-HepB-Hib1, Pneumo131, Rota1, Polio 1; Vaccines scheduled at 10 weeks = DTP-HepB-Hib2, Pneumo132, Rota2, Polio2; Vaccines scheduled at 14 weeks = DTP-HepB-Hib3, Pneumo133, Polio3

Immunization timeliness

We noted that 73.3% of the children were fully vaccinated. The antigen-specific timeliness was 83.2% for BCG, 93.9% for DTP1 and 94.8% for the measles vaccine. The most delayed vaccines were the BCG, IPV and Pneumo133.

Determinants of immunization completeness

The mother’s level of education (secondary or higher level of education) and the father’s profession influenced positively the immunization completeness (Table 4). On bivariate and multivariate analysis, the same determinants: mother’s level of education and the father’s profession increased the infant’s chances of immunization completeness (Table 4).
Table 4

Determinants of immunization completeness

Variables

Immunization completeness

Unadjusted

OR (95% CI)

Unadjusted P value

Adjusted OR (95% CI)

Adjusted P value

Yes

No

Mother’s age

  < 30 years

219(96.9)

7(3.1)

1.51(0.54-4.24)

0.43

  

  ≥ 30 years

166(95.4)

8(4.6)

    

Mother schooled to the higher levela

 Yes

354(97.3)

10(2.7)

5.71(1.84-17.76)

0.007

7.0(2.16-22.68)

0.001

 No

31(86.1)

5(13.9)

    

Profession

 Employed

251(95.4)

12(4.6)

0.47(0.13-1.69)

0.24

  

 Unemployed

134(97.8)

3(2.2)

    

Matrimonial status

 Single

81(96.4)

3(3.6)

1.07(0.29-3.87)

1.00

  

 Married

304(96.2)

12(3.8)

    

Religion

 Christian

352(95.9)

15(4.1)

/

0.62

  

 Muslim

33(100)

0(0.0)

    

Parity

 Primipara

139(96.5)

5(3.5)

1.13(0.38-3.37)

0.83

  

 Multipara

246(96.1)

10(3.9)

    

Father schooled to the higher levela

 Yes

365(96.3)

14(3.7)

1.34(0.16–10.41)

0.56

  

 No

20(95.2)

1(4.8)

    

Father’s profession

 Employed

378(96.7)

13(3.3)

8.31(1.57-43.95)

0.04

12.39(2.21-69.26)

0.004

 Unemployed

7(77.8)

2(22.2)

    

asecondary + university education levels

Determinants of immunization timeliness

Term babies, born at the YGOPH and who were regularly vaccinated there had better chances of being correctly vaccinated. After logistic regression analysis, only term babies had the greatest chance of being correctly vaccinated at the recommended ages (Table 5).
Table 5

Determinants of immunization timeliness

Variables

Timeliness

Unadjusted

OR (95% CI)

Unadjusted P value

Adjusted OR

(95% CI)

Adjusted

P value

Age

 

Yes

No

    

  < 30 years

165 (73)

61 (27)

0.9 (0.6–1.5)

0.9

  

  > 30 years

128 (76.6)

46 (26.4)

    

Level of education

 None/Primary

26 (72.2)

10 (27.8)

0.9 (0.4–2)

0.9

  

 Secondary/Higher

267 (73.4)

97 (26.6)

    

Mother’s profession

 Employed

192 (73)

71 (27)

0.9 (0.6–1.5)

0.9

  

 Unemployed

101 (73.7)

36 (26.3)

    

Matrimonial status

 Single

65 (77.4)

19 (22.6)

1.3 (0.7–2.3)

0.3

  

 Couple

228 (72.2)

88 (27.8)

    

Religion

 Christian

239 (73.3)

98 (26.7)

1 (0.5–2.3)

0.9

  

 Muslim

24 (72.7)

9 (27.3)

    

Parity

 Primipara

105 (72.9)

39 (27.1)

0.9 (0.6–1.5)

0.9

  

 Multipara

188 (73.4)

68 (26.6)

    

Distance from home to vaccination unit

  < 5 Km

149 (74.9)

50 (25.1)

1.2 (0.8–1.8)

0.5

  

  > 5 Km

144 (71.6)

57 (28.4)

    

Father’s profession

 Employed

287 (73.4)

104 (26.6)

1.4 (0.3–5.6)

0.7

  

 Unemployed

6 (66.7)

3 (33.3)

    

Place of birth

 YGOPH

221 (75.9)

70 (24.1)

1.6 (1.01–2.6)

0.04

1.01 (0.9–3.3)

1

 Others

72 (66.1)

37 (33.9)

    

Gestation age

 Term

286 (81)

67 (19)

24.4 (10.5–56.8)

< 0.001

19.3 (8.1–46.1)

< 0.001

 Premature

7 (14.9)

40 (85.1)

    

Place vaccination started

 YGOPH

261 (74.8)

88 (25.2)

1.8 (0.9–3.3)

0.07

  

 Others

32 (62.7)

19 (37.3)

    

Usual place of vaccination

 YGOPH

252 (75.2)

83 (24.8)

1.8 (1.01–3.1)

0.04

2.1 (0.9–4.6)

0.08

 Others

41 (63.1)

24 (36.9)

    

No factor related to the mother or father had a statistically significant relationship with immunization timeliness.

Discussion

An immunization completeness rate of 96.3% was noted. In South Africa, Fadnes et al. [7] in 2011 had a rate of 94%, similar to ours. In Turkey, Torun et al. [8] had a rate of 84.5%, Bofarraj et al. [9] recorded a completeness rate of 81%. Other studies had rates which were much lower than ours: Ba Pouth et al. in 2012 in Cameroon(64.3%) [5], Barreto et al. [10] in Brazil (47%), Chidiebere et al. [11] in Nigeria (30.6%), and 24.3% for Lakew et al. in Ethiopia [12]. These differences could be explained by the fact that these studies were done in communities and on age ranges different from ours. They worked on infants aged 12 to 23 months while we worked on infants aged 0 to 11 months.

The immunization coverage for BCG, DTP3, OPV3 and the measles vaccine [6] were 99.5%, 97.18%, 97.18% and 97.91% respectively. Similar figures were noted by Hu et al. in China, 90.16%, 91.63%, 92.70% respectively for DTP3, OPV3 and the measles vaccine. In Turkey, Ozcirpici et al. [13] noted lower rates, 76.7%, 62%, 62% and 62.7% for BCG, DTP3, OPV3 and measles vaccine respectively.This could be explained by the fact that they worked on larger samples. Lower rates were equally noted by Mohamud et al. [14], in Ethopia with an observed completeness rate for BCG, DTP3, OPV3 and measles vaccine of 41.8%, 41.1%, 41.1% and 24.9% respectively. This difference could be due to the fact that they worked in rural areas.

The father’s profession had a statistically significant relationship with immunization completeness. This relationship persisted after multivariate analysis. Although the vaccines of the EPI are free, there are indirect costs such as transport fees to vaccination sites. If the father is working, these indirect costs could easily be covered; as in the African context, the father is directly responsible for the needs and health of the entire family [15].

For the mother, only the level of education significantly influenced immunization completeness. This association was also found by Gidado et al. in Nigeria [16], Ozcirpici et al. in Turkey [13], Mohamud et al. in Ethiopia [14] and Hu et al. en China [6]. In Yaounde the level of scholarization is 94.3%, and ranks highest amongst all the regions of the country [17]. A litterate woman will better understand messages on vaccination during educational talks, and this increases her awareness of the importance of vaccination. In China, Hu et al. [6] found a significant relationship between the mother’s age, her profession and immunization completeness. In Nigeria, the mothers’s knowledge on vaccination, prenatal care, and information on vaccination, had a positive influence on immunization completeness [16], whereas only the mother’s age was a significant factor, in Ethiopia [14].

No statistically significant association was found between any of the infant’s variables with immunization completeness. However, the place of birth influenced immunization completeness in some studies [6, 14]. It is likely that when a child is born in a hospital, the mother is counseled on maternity and on the care of her baby, and especially on the vaccination schedule.

We observed in our study that 73.3% of the infants were correctly vaccinated. Rates of 88%, 56% and 50%, have been noted respectively in South Africa [7], New Zealand [18], and in the United States [19]. These differences could be explained by the differences in the study sites, sample sizes and study design used. Infants not immunized at the recommended immunization ages have reduced immunity, conducive for development of diseases.

The antigen-specific timeliness was 83.2% for BCG, 93.9% for DTP1 and 94.8% for the measles vaccine. Similar figures have been noted by some authors: BCG (99%), DTP1 (87%) and measles vaccine (85%) [7]; while others had lower figures, 44.59%, 45.38% and 59.25% respectively for BCG, DTP1 and measles vaccine [6].

Children born at term, at the YGOPH, and who were regularly receiving their vaccines there, were more likely to be well vaccinated at the recommended ages. Premature neonates often have to wait untill they are medically stable before starting vaccinations, and this could explain the delay in starting vaccination at the recommended postnatal ages. Besides, children born in the YGOPH and who are regularly vaccinated there, receive more counselling than the others. In China, Hu et al. noted that timeliness of vaccination for specific vaccines was associated with the mother’s age, maternal education level, immigration status, siblings, birth place and distance from the house to the immunization clinic [6]. In South Africa, Fadnes et al. found, the level of education of the mother and the socio-economic status of the parents [7], to be determinants of immunization timeliness.

The fact that the study was done in a single site, which was the vaccination unit of a referral hospital, and in an urban setting in which most mothers are well educated constitutes major limitations of this study. The results might not neccessarily reflect the vaccination status of the entire Yaounde community or Cameroon at large.

Conclusion

This study shows that immunization completeness was quite high but the number of children correctly vaccinated was relatively low. We suggest that more sensitization campaigns be done so as to enlighten parents on the importance of vaccination and on the importance of vaccinating children at the recommended ages.

Abbreviations

AOR: 

Adjusted Odds Ratio

BCG: 

Bacille de Calmette et Guérin

DTP: 

Diphteria tetanus pertusis

EPI: 

Expanded program of immunization

HepB: 

Hepatitis B

Hib: 

Hemophilus influenzae b

IPV: 

Inactivated polio vaccine

OPV: 

Oral polio vaccine

PCV 13: 

Pneumococcal conjugated vaccine 13

Polio: 

Poliomyelitis

WHO: 

World Health Organization

YGOPH: 

Yaounde Gynaeco-Obstetric and Pediatric Hospital

Declarations

Acknowledgements

The authors would like to thank the mothers and caretakers of the children enrolled this study, for their consent to participate and for providing all the required information needed in filling the questionnaires.

Availability of data and material

The dataset analyzed during the current study is available from the corresponding author upon request.

Funding

This study was not funded.

Authors’ contributions

AC, FDN conceived the study. FDN, FN, MK, KK conducted the data collection. GN-T, SN, EM did the data analysis. FN, FDN wrote the first draft of the manuscript. AC, FA revised the draft document and the final manuscript. All authors read and approved the final manuscript.

Ethics approval and consent to participate

The study was approved by the Ethical and Institutional Committee for Research on Human Health of the Yaounde Gynaeco-Obstetric and Pediatric hospital. Reference: No 263/CIERSH/DM/2015 of 8th February 2016. A written consent form was signed by each mother or caretaker who accepted to be enrolled and participate in the study, and for those who could not read and write verbal consent was sought after receiving information on the study.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests; but the corresponding author (Andreas Chiabi) is Associate Editor of BMC Pediatrics – Infection

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Authors’ Affiliations

(1)
Yaounde Gynaeco-Obstetric and Pediatric Hospital, Yaounde, Cameroon
(2)
Faculty of Medicine and Biomedical Sciences, University of Yaounde I, Yaounde, Cameroon
(3)
Institut Supérieur des Sciences de la Santé, Université des Montagnes, Bangangte, Cameroon

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