A retrospective cohort study of childhood immunisation status in northern Sydney

Resources for assessing parents' vaccine hesitancy: a systematic review of the literature

The concept of Vaccine Hesitancy has begun to appear in the scientific landscape, referring to the reluctance of a growing proportion of people to accept the vaccination offer. A variety of factors were identified as being associated with vaccine hesitancy but there was no universal algorithm and currently there aren’t any established metrics to assess either the presence or impact of vaccine hesitancy. The aim of this study was to systematically review the published questionnaires evaluating parental vaccine hesitancy, to highlight the differences among these surveys and offer a general overview on this matter. This study offers a deeper perspective on the available questionnaires, helping future researches to identify the most suitable one according to their own aim and study setting.

Predictors of incomplete immunisation in Victorian children

OBJECTIVE

Using probabilistic record linkage, this study aimed to determine the predictors of incomplete immunisation in Victorian children.

METHODS

Records of all births in Victoria in 1998 were linked with records from the Australian Childhood Immunisation Register (ACIR). The outcomes of interest were the predictors of immunisation status at 12 and 24 months of age.

RESULTS

A total of 91.1% of birth records were linked with records from the ACIR (n=55,129). Immunisation coverage was 92.8% at 12 months and 89.2% at 24 months. After multivariate analysis, the following maternal factors were significant predictors of incomplete immunisation in children aged 12 months: higher parity, 12-23 months interval between pregnancies, not being married, Aboriginal or Torres Strait Islander or born overseas, younger age, no private health insurance, home birth, metropolitan place of birth, and being in the highest or lowest socioeconomic quintiles. Low birthweight and singleton birth were also significant predictors. All of these factors were also predictive of incomplete immunisation in children aged 24 months, with the exception of low birth weight, which was only significant in the very low birth weight category. Congenital malformations or prematurity were not significant predictors.

CONCLUSIONS AND IMPLICATIONS

Record linkage is an effective means of determining the relationship between immunisation status and socio-demographic and health-related factors. It enabled small groups within a large population to be studied, confirming findings from previous survey studies and indicating that several population groups were at increased risk of incomplete immunisation. The main limitation of the study was the under-reporting of immunisation status to the ACIR.

Mothers' health post-partum and their patterns of seeking vaccination for their infants

A cohort of 159 mothers were recruited post-partum and followed for seven months to examine the relationship between mothers' health post-partum and their patterns of seeking vaccination for their infants. Vaccination records for infants were obtained from a state-wide database. Only 44% of the mothers had maintained all age-appropriate vaccinations for their infant up to six months of age. Mothers who had two or more older children were four times more likely to have an infant who was not age-appropriately vaccinated at six months. Women experiencing mental health problems including anxiety and depression, seven months following the birth, were between three to five times more likely to have started the vaccination schedule late or not at all. The findings have implications for midwives and for nurses practising in maternal and child health, paediatrics and public health environments. Strategies focusing on enhancing mothers' psychosocial well-being postnatally through improved service delivery should improve their patterns of seeking vaccination for their infants.

Increases in vaccination coverage for children in child care, 1997 to 2000: an evaluation of the impact of government incentives and initiatives

OBJECTIVE

To compare vaccination coverage of children in child care before (1997) and after (2000) implementation of government immunisation strategies including parent/providers incentives and surveillance of vaccination uptake.

METHODS

Cross-sectional parent surveys of vaccination coverage for children (<3 years old regularly attending child care) in 47 child care centres and 19 councils operating family day care in metropolitan Melboume.

RESULTS

Data were collected for 1,578 (72%) children in 1997 and 1,793 (72%) in 2000. In 2000, 93% were completely immunised, a 9% (95% CI 6%-11%, p<0.001) increase from 1997. Less than 1% of children were unimmunised (0.8% in 1997, 0.5% in 2000). For those >2 years, 94% were completely immunised before their second birthday in 2000 compared with 80% in 1997. Immunisation levels were 10% (95% Cl 6-12) higher in 2000 than in 1997 for those receiving child care benefits compared with a 7% (95% Cl 3-10) increase for families not receiving benefits. In 1997, 8 (17%) child care centres and 4 (21%) councils reported > or = 90% children completely immunised increasing to 33 (70%) and 16 (84%) in 2000 respectively. Fewer families reported delaying immunisations because of minor illness in 2000 (27%) compared to 1997 (44%, p<.001). Updating immunisation data by child care coordinators increased from 51% in 1997 to 98% in 2000.

CONCLUSION

A substantial increase in immunisation uptake has been achieved for this population of young children attending child care. This study provides evidence that the increase in vaccination rates is attributable to some extent to increased surveillance of immunisation rates and both parent and provider incentives to immunise.

Immunization coverage of Australian-born children of Arabic-speaking background in Central Sydney

OBJECTIVES

To examine the immunization coverage rates of 12-36-month-old Australian-born children from an Arabic-speaking background in Central Sydney as determined by parental report and documentary evidence.

METHODOLOGY

Eligible children were identified by examination of the records of five hospitals. Eligibility criteria were that the mother gave an Arabic speaking country of birth and a Central Sydney post code (as her place of residence) and the child was born between 1 May 1994 and 30 April 1996. Parents of all eligible children were invited to participate, either by a special appointment to answer a structured questionnaire, or by telephone survey. Of the 1157 eligible children identified from hospital birth records, only 641 could be contacted, of whom 584 (91.1%) agreed to participate. Full information on age appropriate immunization rates, as reported by parents and documented in records, could be assessed for 403 children.

RESULTS

Parents reported that 97.6% of children were fully immunized. When the child's immunization status could be verified from either the child's personal health record and/or the service provider, the rate of full, age-appropriate immunization was 94.3% (95% confidence intervals 92.0-96.6) compared to a parent-reported rate of 98.0%. General practitioners provided 76.2% of immunizations.

CONCLUSION

While a substantial proportion of children identified from birth records could not be contacted, comparisons with census data and other analyses indicate that this sample is likely to be representative of the general population of 12-36-month-old Australian-born children from an Arabic-speaking background. This group appeared to be highly immunized. Further studies examining why the rates for this ethnic group are high in Central Sydney may determine strategies which will enhance immunization rates in other communities.

An attempt to swindle nature: press anti-immunisation reportage 1993-1997

There is some evidence that low childhood immunisation rates in Australia may be attributed partly to parental antipathy toward immunisation. The anti-immunisation movement is becoming more organised in its efforts to lobby against childhood immunisation, while the lessening of the public's exposure to the effects of vaccine-preventable disease has provided a climate ripe for such a lobby to have a disproportionate influence on parents. Forty months of Australian print media coverage of immunisation were reviewed for anti-immunisation arguments and their underlying ideological subtexts. Of 2440 articles about childhood immunisation, 115 (4.7 per cent) contained statements opposing immunisation. Eight subtexts that referenced wider discourses about medicine, the state and the body dominated anti-immunisation discourse (cover-up; excavation of the facts; unholy alliance for profit; towards totalitarianism; us and them; vaccines as poisonous chemical cocktails; vaccines as cause of idiopathic ills; and back to nature). Attempts to redress claims made against immunisation must not only address specific claims about vaccine efficacy and safety but be grounded in a reframing of the ideological appeals that currently frame the contents of anti-immunisation discourse.

Fragmentation of scheduled visits and missed doses among infants receiving multiple injected vaccines

A retrospective cohort study was used to determine the extent to which immunisation visits due in the first year of life are split into separate visits. A one-month birth cohort of infants registered in early childhood health centres in the former Eastern Sydney Health Area was followed up when the infants were 8 to 11 months of age. A telephone questionnaire sought documented dates of each dose in the primary series of diphtheria-tetanus-pertussis (DTP), Haemophilus influenzae type b (Hib) and hepatitis B (HBV) vaccination. Of the 141 subjects, 130 had received all due doses of DTP and Hib vaccines and 63 (45 per cent) had been enrolled in the neonatal hepatitis B program. Infants in the latter group received the first DTP-Hib dose on average one week later than did those not in the hepatitis B program (DTP, P = 0.016; Hib, P = 0.047). The greatest percentage of missed DTP or Hib doses occurred in infants not receiving HBV vaccination (7.1 per cent of doses) or those high-risk infants enrolled in the neonatal hepatitis B program (2.9 per cent). Overall, 12 infants had 28 (6.9 per cent) of the 404 possible scheduled visits fragmented into two separate visits. In all cases, parents reported that this was at the suggestion of the general practitioner. We found no greater likelihood of fragmentation for infants who had also received hepatitis B vaccine. Only 17 infants (29 per cent) had received the third hepatitis B vaccine and DTP doses at the same visit, as recommended. These findings confirm anecdotal reports of fragmentation of scheduled visits and missed doses for infants due to receive multiple injections, and some delay in uptake among those receiving hepatitis B vaccine. Universal infant hepatitis B immunisation should not be considered until combination vaccines (which should also include a Hib component) become available in Australia.

An evaluation of 1994 school entry immunization certificates on the Central Coast of New South Wales

OBJECTIVE

To evaluate school entry immunization certificates and document the immunization status of children enrolled during 1994 in kindergartens on the NSW Central Coast.

METHODOLOGY

Immunization certificates and non-statutory documentation of immunization for school entry presented by parents were evaluated during visits to 68 NSW Central Coast schools in May and June 1994.

RESULTS

Immunization information for 3741 kindergarten enrollments was reviewed. Of these enrollments, 79% presented immunization certificates of which 10% were incomplete, 14% presented non-statutory documentation and 7% had no certificate or non-statutory documentation. It was considered that 19% of children were incompletely immunized; 8% of certificates presented were incorrectly completed.

CONCLUSIONS

The study found that about 80% of Central Coast school entrants were fully immunized. Reliance on immunization certificates as evidence of immunization may overestimate vaccination completion rates, as some certificates may be incorrectly completed. Education of parents, school staff and certificate providers should help to improve both immunization completion and documentation.

A population-based survey of immunisation coverage in two-year-old children

A cross-sectional, population-based, cluster-sample survey of 187 children was conducted in the Newcastle area to assess the proportion of two-year-old children who were fully immunised, to ascertain whether administration of these vaccines was age-appropriate and to look for factors predicting incomplete immunisation. Parents or guardians were interviewed at their homes and the immunisation status of the children was verified either by the parent-held record or by the immunisation-provider-held record. Levels of full immunisation were 77 per cent at the time of interview and 72 per cent at the second birthday if Haemophilus influenzae type b (Hib) vaccine was excluded. If it was included, the full immunisation level was 51 per cent. Coverage was highest for oral polio vaccine and lowest for Hib vaccine. Twenty-nine per cent of all immunisations were given early, 44 per cent were given on time and 20 per cent were given late. Doses of vaccines due at older ages were more likely to be given late or not at all. Factors predicting incomplete immunisation were: the principal caregiver being aged under 25 years, being born outside Australia, having post-secondary qualifications, being female and having more than one child in the household. Immunisation coverage levels were not high enough to protect against outbreaks of pertussis and measles and cases of Haemophilus influenzae type b. Immunisation providers should aim to increase coverage to protect the population against all vaccine preventable diseases, and aiming at high-risk groups could more effectively do this.