Do socio-demographic variables influence the uptake of ...



Socio-demographic variables and parental decision-making about childhood vaccines - is education more important than deprivation?

Stephanie Palmer, PhD, Tumana Research, Coromandel

Rob McNeill, PhD, Centre for Health Service Research & Policy, Univeristy of Auckland

Abstract

This paper provides a new platform for considering the role of demographic variables in decision-making about childhood vaccines by New Zealand. 436 parents and guardians, of at least one child aged 16 years or younger completed an anonymous survey on demographic variables; completeness of childhood vaccines and intention to vaccinate or accept a hypothetical new vaccine. Despite evidence of social disadvantage, Māori care-givers were more likely to have fully vaccinated, less likely to have partially vaccinated children, had the highest vaccination intentions and were most willing to accept a new vaccine. Across all ethnic and income groups, care-givers with a university degree or higher were consistently least likely to vaccinate. This research suggests a child’s vaccination status is mediated by parental education which, in turn, interacts with both ethnicity and income. Such outcomes challenge national coverage data in which lower rates of vaccination have been firmly attributed to ethnicity and deprivation.

Introduction

There are studies to both uphold and refute the role of socio-demographic variables in determining parental uptake of childhood vaccines. In the provincial town of Wairoa, for example, an audit of general practices found no evidence to suggest ethnicity or poverty were deterrents (1). Several international studies have also shown that uptake is not associated with parental race (2, 3), country of origin, ethnicity in a low income urban population (4), maternal co-residence with father (3), marital status, gender, maternal age, number of children, median age of oldest child, education, occupation (5-7), income, employment and socio-economic status (8, 9).

However, a far greater body of work suggests the uptake of childhood vaccines may be associated with, even determined by, socio-demographic variables. Indeed, lower uptake has been consistently associated with the poorest sectors of society. In the USA, a number of large studies have shown that under-vaccination is significantly more common among children of younger, less educated, multiparous, unmarried or sole-parenting mothers in non-White minority groups as well as low income, inner city and larger families (3, 10-15). Similarly, in Australia and the UK, partial or incomplete immunisation has been associated with indigenous or minority group ethnicity, higher maternal parity, closely spaced pregnancies, larger family size, lone or teenage parenthood, inner city or rural dwelling, unemployment, living in the lowest socio-economic quintile and other indicators of disadvantage such as no private health insurance, maternal smoking in pregnancy, low birthweight and infant admission to hospital before 9 months (16-18). Among a million Scottish children, born 1987-2004, late vaccination was predicted by deprivation and social disadvantage (19). Furthermore, lower rates of uptake have been associated with family transience, maternal drug-use, refusal to participate in supplementary state support programmes, grandparents not living in the household, urban-based families and inadequate access to health care services (13, 18, 20-22).

Within Aotearoa, several indicators provide reason to suggest uptake is lower among the socially disadvantaged. The latest coverage survey, of more than 1300 households (23), found full immunisation was less likely when children were living in low income or mobile households with caregivers who were lone parents, of Māori ethnicity or without formal qualifications. Indeed, household mobility and indigenous Māori ethnicity were significant risk factors for incomplete vaccination at 2 years of age. Compared with Europeans and other minority groups, Māori children were less likely to be vaccinated on time or up-to-date with the recommended schedule of vaccines at 5 months, 1 year and 2 years of age.

General description of raw data gathered through the recently established National Immunisation Register (NIR) further highlights the influence of disadvantage (24-26). In comparison with children in all other ethnic groups, indigenous Māori have consistently demonstrated the lowest rates of coverage. By socio-economic deprivation, this database also shows children living in the most disadvantaged households are least likely to be fully immunised at 6 months, 1 year, 18 months and 2 years of age. Such findings are supported by a few qualitative studies (27, 28). Among Pasifikā children, for example, lower uptake has been linked to maternal smoking, high parity and experience of transport difficulties (29, 30).

Irrespective of ethnicity or deprivation, NIR data for the last three years shows coverage levels are lowest when babies are 6 months old, peak at twelve months then decline after the first year of life. Such findings suggest parental decisions about the uptake of vaccines may be influenced by their child’s age. New Zealand’s literature has also shown Pasifikā mothers with higher levels of education and fluency in English may be less likely to vaccinate (29). Indeed, parents who choose not to immunise are known to be very highly educated, often with a tertiary qualification (31). Highly educated parents, who are usually more affluent, also have more concerns about the safety of vaccines and school-based vaccination campaigns (32, 33). Furthermore, up to 25 percent of practice nurses may have concerns that could undermine parental confidence in childhood vaccines (34).

A raft of international studies have produced evidence which suggests that highly educated parents have more concerns about childhood vaccines and are less likely to vaccinate (35-40). After adjusting for other socio-demographic factors, several Australian studies have shown that children of the highly educated are less likely to have had the triple-DTP, MMR or varicella vaccines (9, 18), more likely to be completely unimmunised (41) and have more risk of incomplete vaccination (42-44). Highly educated Australian parents are also more likely to decline vaccines (45), have more concerns about the safety of vaccines and are less confident about the benefits of routine vaccination (18). Similar themes are evident in peer-reviewed literature from the United States (2, 5, 10, 12, 13, 46, 47), Netherlands (6, 48), United Kingdom (7, 16, 38, 49-52), Canada (53), Scotland (19, 54), Switzerland (55), Sweden (56), Israel (57), Turkey (58) and Belgium (59).

It seems highly educated parents (who are often more affluent) are both more and less likely to vaccinate (5, 18). In Australia, for example, incomplete vaccination is predicted by socio-economic status in the lowest and highest groups (17). Affluent Scottish parents tend to vaccinate promptly or not at all (19). Children in higher socio-economic groups have also been shown to be at more risk of partial vaccination and not being up-to-date with vaccines (2),(58) as well as less likely to receive the Hepatitis A, Hepatitis B or MMR vaccines (47) (54) (57). Other studies have shown that highly educated parents are less likely to say vaccination is important (46), less likely to support universal vaccination (56), more likely to refuse vaccines (47) (7, 16) (57, 58) and have more concerns about vaccine safety as well as school-based vaccination campaigns (6) (7), (38).

In the UK, two population studies found MMR coverage was higher among the affluent prior to 1998 then declined more rapidly in affluent than deprived areas (50, 51). By way of explanation, the authors have suggested the affluent are first to take up practices known to improve child health which, in the latter part of this decade, has involved questioning the need for childhood vaccines. In accordance with this theme, selective refusal of childhood vaccines is known to be more prevalent among patients in private practice (60) and highly educated parents are less likely to enter their infants in a phase III vaccine trial (53). In comparison with the general population, it seems health professionals may have more negative attitudes to vaccines (12, 48, 61). In Switzerland, for example, many health professionals, including paediatricians, are known to decline, delay or not follow government recommendations when vaccinating their own child (55), Similarly, in Israel, a fifth of the mothers who declined to give their newborn infant the Hepatitis B vaccine worked in medicine or health-related fields (57). In comparison with their community-based peers, one study has found that hospital-based health professionals have more concerns about childhood vaccines (62).

It seems the socio-demographic characteristics which determine under-vaccination may differ from those of not being vaccinated at all. Indeed, various studies have shown that under-vaccination is associated with, even predicted by, deprivation and disadvantage but non-vaccination, or not being vaccinated at all, is more aptly linked to social advantage (6, 10, 12, 16, 18-20, 39, 58, 59). In decision-making about the varicella vaccine, for example, highly educated Australian parents declined because their child had already been infected or the disease itself was considered mild. In contrast, parents in the lower socio-economic groups didn’t vaccinate because the service was hard to access but they had more concerns about the complications of disease and felt it was more serious (9).

With mixed results, a number of authors have tried to quantify the impact of socio-demographic factors on vaccination status or intentions. Some have said more than 80 percent of the variance in under-immunisation is attibutable to social disadvantage and associated inequalities in healthcare (11). In contrast, a New Zealand study found demographic variables accounted for less than 1 percent of the variance in vaccination intentions but emotional factors and risk/benefit perceptions explained 21 to 42 percent (63). Others have suggested social disadvantage accounts for less than 10 percent of the variance in under-immunisation (64). Using complex Bayesian techniques with synthesis of qualitative and quantitative evidence, a conclusive study has shown that structural issues, including access and socio-economic variables, have less influence on vaccination status than lay beliefs, advice received from health professionals and child’s health history or wellness on the day (65).

Amidst such uncertainty, there is a need for studies which help to clarify the role of socio-demographic variables in decision-making about childhood vaccines by New Zealand parents. Alongside parental education, it would be of interest to know whether vaccination is more likely among first born infants (14, 20) or less likely when mothers are older (66),(16) and, in any way associated with a child’s age (8, 23, 24, 50), maternal parity or family size. (2, 7, 16, 17, 20, 29) The following paper examines these issues using data extracted from a survey which looked at parental decision-making about childhood vaccinations in a provincial region of New Zealand.

Methodology

Parents and guardians, of at least one child aged 16 years or younger, were invited to complete an anonymous survey which collected data on demographic variables; whether tamariki in their care had received all, some or none of the scheduled vaccinations and intention to vaccinate the next child or mokopuna in their whānau as well as accept a hypothetical new vaccine.

The recruitment strategy was initially self-selecting with respondents having the opportunity to complete and return the survey by freepost within a 3 month period. Pre-schools, kindergartens, playcentres, Kōhanga Reo, schools and Kura Kaupapa Māori throughout the region distributed the survey to students and whānau. Midwives, La Leche League, Parent’s Centre, Homebirth Aotearoa and other relevant organisations helped with distribution of the survey. Display-boards containing the information sheet and survey forms were set-up in health shops, medical centres and local hospital. Participation was promoted in media interviews, posters and fortnightly newspaper notices. After this initial 3 month period, a more active strategy of kānohi kitea, or face-to-face meetings, with Kōhanga Reo and Kura Kaupapa whānau was implemented to encourage Māori participation.

Raw data was entered onto an EXCEL spreadsheet then checked and analysed using SPSS for Windows, version 13. Data-analysis primarily aimed to compare differences in response patterns for vaccination status and intentions. General exploratory techniques were used to describe all variables. Pearson’s correlation was used to check for statistical significance when-ever a logical linear relationship was possible between two variables. Chi2 and one-way ANOVA helped to explore and identify between-group differences. Estimated marginal means (EMM) were used to check for interaction between variables. A vaccination score was constructed from average responses to the items on individual child vaccination status.

Results

Table 1 presents the demographic profile of 436 parents and caregivers who completed the survey during April-October 2006. Most participants were in the main parenting age-group 26-45 years but 3 percent were younger than 25 years and 16 percent were 46 years or older. In comparison with Pākehā, Māori participants were more likely to be teenagers or older than 46 years.

Eighty-two percent were of Pākehā/European ethnicity and 16 percent self-identified as Māori. The 12 remaining participants affiliated with Pasifikā, Asian or other ethnicities, mostly English and South African. Over 90 percent of participants were women including 38 wāhine hapū (pregnant women) of whom 8 were Māori. Most participants had gained a post-school certificate or diploma but 34 percent had high school education and 24 percent had obtained a university degree. Older participants were significantly more likely to have a degree (r = .102, p ................
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