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| Journal of the New Zealand Medical Association,
06-August-2004, Vol 117 No 1199
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Maternal and demographic factors associated with
non-immunisation of Pacific infants living in New Zealand
Janis Paterson, Teuila Percival, Sarnia Butler, Maynard
Williams
Compared with most New Zealand children, Pacific children
are at increased risk of poor health with a higher incidence of respiratory
infections, meningococcal disease, and infectious diseases such as
measles.1–3
Immunisation has been described as the first line of defence
against disease, and one of the most effective health advantages available to
children.4,5 Ensuring full and equitable
distribution, accessibility, and acceptability of this health opportunity is an
important health priority.5 The New Zealand
immunisation schedule commences at 6 weeks of age and national immunisation
targets have been set to achieve at least 95%
coverage.6
Despite the demonstrated effectiveness of immunisation,
current policies have become increasingly controversial due to concerns about
vaccine safety. However, national and international scientific consensus is that
any risks associated with immunisation are outweighed by its
benefits.7
There are no reliable New Zealand population-derived data on
immunisation rates for 6-week infants. A recent study found that 93.2% of a
cohort of 979 children (registered with the childhood register in Wellington)
had received their 6-week vaccines. However, this information was collected from
those who remained registered with the practice and was calculated after 9
months of age.8
Research has shown that children who are not immunised on
time are likely to be from families of low socioeconomic status, to live in
urban areas, and to be members of ethnic minority
groups.9,10 Other identified risk factors
associated with sub-optimal uptake of immunisation include low parental
educational level, inability to access appropriate transport, and single parent
family.11 Also found to contribute are rising
parity,12 inadequate antenatal
care,13,14 negative beliefs about
immunisation,9,11 and child health on the day
of the appointment.9 Such risk factors suggest
the need for further investigation into specific populations and the
identification of barriers within subgroups.11
In view of the high rates of infectious disease and
hospitalisation among Pacific infants,1–3
the Pacific Islands Families Study included questions designed to identify the
proportion of infants who had not received their first dose of the primary
immunisation series, as well as the maternal and demographic factors associated
with non-immunisation.
MethodsData were collected as part of
the Pacific Islands Families: First Two Years of Life (PIF) Study. The PIF Study
is a longitudinal investigation of a cohort of 1398 infants born at Middlemore
Hospital, South Auckland during the year 2000.
Middlemore Hospital was chosen as the site for
recruitment of the cohort as it has the largest number of Pacific births in New
Zealand and is representative of the major Pacific ethnicities. All potential
child participants were selected (from live births at Middlemore Hospital) if
the child had at least one parent who identified as being of a Pacific Island
ethnicity and who also was a New Zealand permanent resident.
Recruitment procedures occurred through the Birthing
Unit in conjunction with the Pacific Islands Cultural Resource Unit that
provided a daily list of Pacific admissions. Mothers were given a general
description of the interview protocol, but specific areas such as immunisation
were not discussed at the time of recruitment.
Approximately 6 weeks after the birth of their child,
Pacific interviewers, fluent in both English and a Pacific language, visited the
mothers in their homes to carry out the first interview. However, as some
mothers were difficult to trace, it was not possible to administer all
interviews precisely at 6 weeks.
Once eligibility criteria were established and informed
consent gained, mothers participated in a 1-hour interview concerning the health
and development of the child and family functioning. This interview was carried
out in the preferred language of the mother. All procedures and interview
protocols had ethical approval from the National Ethics Committee. Detailed
information about the cohort and procedures is described
elsewhere.15
Mothers responded to questions about whether their
child had been immunised, who administered the vaccines, and how satisfied they
were with the care and treatment of their child in that context. Maternal and
sociodemographic factors that may be associated with non-immunisation was
assessed by univariate and multivariate logistic regression procedures.
ResultsNinety-six percent (n=1590) of
potentially eligible mothers of Pacific infants (who had been born between 15
March and 17 December 2000) gave consent to be visited in their homes when the
infant was 6 weeks old.
Of the 1477 mothers contacted and who met the eligibility
criteria, 1376 (93.2%) agreed to participate in the study. A more conservative
recruitment rate of 87.1% would include mothers who consented to contact and
were confirmed eligible, or of indeterminable eligibility due to inability to
trace.
Of the 1376 mothers in the cohort (1.7% gave birth to
twins), 47.2% self identified their major ethnic group as Samoan, 21% as Tongan,
16.9% as Cook Islands Maori, 4.3% as Niuean, 3.4% as Other Pacific, and 7.2% as
Non- Pacific.
The Other Pacific group includes mothers identifying equally
with Pacific and Non-Pacific groups, or with Pacific groups other than Samoan,
Tongan, Cook Island Maori, or Niuean. The Non-Pacific group refers to mothers of
infants fathered by Pacific men. The mean (SD) age of mothers was 27 (6.2)
years, 80.5% were married or in de
facto partnerships, 33% of mothers were New Zealand-born, and 27.4% had
post-school qualification.
Approximately 73% of the mothers reported that they had
immunised their infant. The majority of these mothers (97.1%) reported that they
were satisfied with the care provided by their doctor. The main problems that
were cited by mothers were being unhappy with the treatment, or having
difficulties associated with communicating with the doctor.
Table 1 lists the variables examined for potential
association with non-immunisation of infants in the cohort. For the categories
within each variable, the numbers and percentages of mothers who did not have
their infant immunised are given, along with the associated odds ratios. Mothers
who were under 20 years of age, with post-school qualifications, and those who
described themselves as fluent in English were significantly less likely to have
had their infant immunised at 6weeks of age.
Strong cultural alignment with the Pacific, but not New
Zealand, way of life and customs, and difficulties with transport were also
significantly (p<0.05) associated with non-immunisation. With regard to
specific ethnicity, Samoan mothers were significantly more likely to report that
they had immunised their infant. The age of the infant at the time of the
interview was also significantly associated with non-immunisation. Those infants
who were older than 8 weeks were significantly more likely to have been
immunised than younger infants.
Maternal birthplace, household income, attendance at
antenatal classes, parity, social marital status and number of years lived in
New Zealand did not reach significance.
Table 1. Numbers (row percentages) and univariate odds
ratios for non-immunisation of 6-week infants by selected variables
When controlling for the effects
of all Table 1 variables in a multiple regression model, factors that were
significantly associated (p<0.05) with non-immunisation were ethnic group,
maternal birth place, parity, difficulty with transport, and age of the baby at
the time of the interview.
DiscussionThe finding that over a quarter of
mothers (26.7%) had not had their child immunised at approximately 6weeks of age
demonstrates the need for education about the importance of immunisation and
schedules, together with community resources to support mothers in the context
of this infant healthcare initiative.
When controlling for a range of potentially confounding
variables, including the age of the child at the time of the interview, those
mothers who were less likely to have their child immunised with the first dose
of the primary immunisation series were: Pacific born, had more than 5 children,
and had difficulty with transport.
Pacific-born mothers may have less knowledge about
immunisation schedules, which is likely to impact on their decision as to
whether to have their child immunised in infancy. These findings also suggest
that those mothers with a large number of children and those who had limited
access to transport may find it difficult to get to their GP or clinic. It
appears that improving immunisation coverage through education may not be
sufficient and that the more widespread issues of deprivation and social equity
need to be addressed.16 In terms of ethnicity,
Tongan, Cook Islands Maori, Niuean, Other Pacific, and Non-Pacific mothers were
significantly less likely than Samoan mothers to have had their child immunised.
The age of the infant when the interview was conducted was
significantly associated with non-immunisation, with those infants older than 8
weeks more likely to have been immunised. Thus, if all interviews had been
carried out at 8 weeks, then the proportion of infants who had received their
first immunisation dose is likely to be higher.
We did not look at factors that may be associated with a
delay in immunisation. One factor that has been highlighted in previous research
is that Pacific parents are more than twice as likely to believe that
immunisations are too upsetting and painful for very young
children.17
Information and reassurance (pertinent to specific problems
that parents are experiencing) are thought to have maximum effect on parental
commitment to immunisation.18 Studies have
shown that some children are not appropriately immunised because their mothers
are not given satisfactory information. Furthermore, many parents lack
first-hand experience with diseases, and may underestimate their communicability
and potential harm.16
Findings from qualitative investigations have highlighted to
the problems associated with long waiting times,
12 lack of discussion time with the
doctor,19 crowded clinics, and the bringing and
minding of other children.11
It has been suggested that opportunistic immunisation by
doctors,20 flexible immunisation provision, and
government incentives 21 may be the key to
higher immunisation levels. Accurate, accessible and current records, and
effective tracking systems would further facilitate a clear understanding of
immunisation status, and help identify children who are at high risk. It is
equally important that interventions provide ongoing supportive environments (to
facilitate access to immunisation services for mothers at each point in the
immunisation process).
There are several limitations that need to be considered.
Firstly, the study does not provide a comparative group of non-Pacific infants.
Secondly, it was the intention of the study to collect data at 6 weeks; however,
due to difficulties tracking some families, all infants were not reached
precisely at that time. Our data shows that those infants visited later were
more likely to have been immunised, thus it is possible that the infants visited
earlier (at 6 weeks), who were not immunised, may have received their
vaccinations in the following months.
However, the Pacific Islands Families Study does begin to
provide data in this area of recognised public health importance where, despite
being a Child Health priority, robust contemporary data are lacking.
Furthermore, longitudinal analysis at 12 and 24 months will build a clearer
picture of immunisation patterns among Pacific children living in New Zealand.
Author information:
Janis Paterson, Associate Professor and Co-Director, Pacific Islands Families:
First Two Years of Life Study, Auckland University of Technology, Auckland;
Teuila Percival, Paediatrician, Kidz First Children’s Hospital and
Community Services, South Auckland Health; Sarnia Butler, Research Fellow,
Pacific Islands Families: First Two Years of Life Study, Auckland University of
Technology, Auckland; Maynard Williams, Senior Research Fellow and Statistician,
Faculty of Health, Auckland University of Technology, Auckland
Acknowledgments The
Pacific Islands Families (PIF) Study is funded by grants awarded from the
Foundation for Research, Science and Technology, the Health Research Council of
New Zealand, and the Maurice & Phyllis Paykel Trust. The authors gratefully
acknowledge the families who have participated in the study as well as other
members of the research team. In addition, we thank the PIF Pacific Advisory
Board for their guidance and support.
Correspondence: Dr
Janis Paterson, Faculty of Health Studies, Auckland University of Technology,
Private Bag 92006, Auckland. Fax: (09) 917 9877; email: janis.paterson@aut.ac.nz
References
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