The results in brief

• Parents who received information during pregnancy that discouraged immunisation were up to twice as likely to not get their children vaccinated on time – the effect was greater if the mother was the one who received the information. Receiving encouraging information, on the other hand, proved to have no effect on the timeliness of immunisations.
• Over half (56%) of pregnant women do not receive any information regarding immunisation of their child prior to her/his birth.
• 39 percent of pregnant women and 30 percent of their partners received information that encouraged immunisation. In comparison, 14 percent of mothers and 13 percent of their partners received information that discouraged them from immunising their child.
• Encouraging information was most commonly given by midwives, family doctors and family members to both pregnant women and their partners.
• Family and friends, and media were the most common sources of information that discourages immunisation for both pregnant women and their partners.
• While healthcare providers were the most frequent source of encouraging information they were also the identified source of 16 percent of the discouraging information.
• One third of pregnant women only received discouraging information about immunisation.

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Negative messages about immunisation have a far greater impact on parents’ decision to delay vaccinations than encouraging information has on vaccinating children on time, reveals a new policy brief released today by the Growing Up in New Zealand study.

The brief shows that pregnant women and their partners who received information that discouraged them from immunising their child were twice as likely to not get their children vaccinated on time compared to parents who did not read the information. The effect was greater if the mother was the parent who received the material, with timely vaccinations dropping from 73 to 60 percent.

Receiving encouraging information on the other hand proved to have no effect at all on the timeliness of immunisations in the first six months of the children’s lives. The rate of immunisations that were given on time remained at 71 percent, regardless of whether parents received encouraging information or not.

“Immunisation is one of the most effective – and cost-efficient– ways to prevent disease and improve health, especially in young children,” says Growing Up in New Zealand Associate Director and Starship paediatrician, Associate Professor Cameron Grant from the University of Auckland.

“Babies in their first year of life are particularly vulnerable to complications from serious diseases that can be stopped with a simple vaccine. This includes whooping cough, diphtheria, measles, polio and some forms of meningitis and pneumonia.”

“That’s why it is concerning to see that warnings against immunisation are having such a big impact on parents’ decision to delay vaccinations or not vaccinate their young children at all.”

To find out about parents’ intentions regarding vaccination, the Growing Up in New Zealand study interviewed 6822 women and 4404 of their partners during the last trimester of pregnancy. The researchers asked questions about parents’ plans to immunise their child, the materials they received about vaccination, and where they received them from. Infants were considered to have been immunised on time if each of the recommended six-week, three-month and five-month vaccines were given within 30 days of the due date.

Close family and friends, and the media were found to be the main influences on parents’ decision not to immunise their child or to delay vaccinations. The study found that parents-to-be were most likely to receive discouraging information about immunisation from their next of kin, and from TV, radio and the internet.

“It is important to understand why positive messages about immunisation are not getting through to all parents-to-be,” says Dr Grant.

“One reason could be that the information does not outline the risk of not vaccinating a child clearly enough. Few of today’s parents would have personally experienced or seen the life-threatening complications that diseases such as diphtheria can cause, thanks to widespread vaccine coverage in New Zealand which is currently sitting at 93% at age 8 months and 2 years for the overall population.”

“We will also need to rethink how official information about immunisation is distributed to parents in light of addressing why there is a high number of parents who don’t receive any information at all, and why some parents only receive warnings through the media, and via family and friends,” says Dr Grant.

Social Policy and Evaluation Research Unit (Superu) Chief Executive Clare Ward says, “This study has revealed that only 44% of pregnant women receive information about immunisation which is the time when these decisions are commonly made.”

“Other areas for improvement that we have learned through this research are to ensure that immunisation information is being aimed at both parents. Additionally, if some parents are stating that the messages they receive from primary health providers on immunisation is negative – can we review what we are saying and how that is possibly being misinterpreted?” asks Ms Ward.

“Through this longitudinal study we will be able to observe these families over time and their future immunisations and health,” says Ms Ward.

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Download the policy brief

Policy Brief 6: Who is saying what about immunisation - evidence from Growing Up in New Zealand (PDF)

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Media coverage

• New Zealand Herald
• Radio New Zealand Morning Report
• TV One News
• Newstalk ZB