Progress to immunisation coverage in NZ 2013
Measles is a highly infectious virus that spreads easily from person to person through the air, by breathing, coughing and sneezing. It affects both children and adults and is easily stopped by vaccination.
The National Serosurvey of Vaccine Preventable Diseases 2005-2007 shows that immunity against measles increases with age. In the recent years, given the combined effect of increasing immunisation coverage and decreasing incidence of measles, immunisation has been the main contributor to measles immunity.
The 2011-2012 measles outbreak showed measles incidence rate decreased with age, also supporting that immunity increases with age. As well, the secondary peak of measles incidence seen in 2009 and 2011 outbreaks in the 10-14 age group is compatible with the lower immunity of those born between 1990 and 2000 found in the serosurvey.
The most vulnerable age groups remain children under one year of age followed by those between 1 and 4 years: these were the groups the most affected by the 2011-2012 measles outbreak—particularly the children between 6 and 24 months of age.
According to the World Health Organisation, 95% of the population need to be immune in order for measles to be eliminated. This means 95% of people born since 1969 need to have two shots of measles vaccine. The New Zealand National Immunisation programme supports timely routine immunisation.
Further information on measles immunisation coverage and measles immunity is presented here. Figure 1 shows that an average of 81% of two-year-old children have been immunised with the first dose of measles containing vaccine over the 1980–2012 period. In 2011, New Zealand had the highest ever recorded coverage for first dose of MMR (93.2%).
Figure 1: Immunisation coverage of first dose of measles vaccine at the age of two years (1980 to 2012)
Recent Measles Mumps Rubella (MMR) vaccine coverage rates by birth cohort
Recent MMR vaccine coverage rates by birth cohort were analysed by using enrolment and MMR vaccination data extract from National Immunisation Register (NIR) on 2 September 2013.
Nationally, the MMR coverage for dose one was 93.1% for the 2011 birth cohort and it ranged between 92.0% and 94.0% for the birth cohorts 2006–2011. MMR coverage for dose two was around 89% for the 2006 and 2007 birth cohorts. This coverage is not high enough to stop outbreaks of measles. Catch up measles vaccination is free to anyone who needs it.
MMR coverage for dose one is shown for each yearly cohort of children from 2006 to 2011. MMR coverage for dose two is shown for children born in 2006 and 2007. The cohorts of children born during 2008 were still completing their second dose in 2013 (scheduled for age four). MMR coverage for dose one and two is reported at national and DHB level, as well as by ethnicity and deprivation quintiles (NZDep 2006).
Table 1 presents national immunisation coverage by birth cohort for dose one and two from 2006 to 2011. It shows the number of children in each cohort at the national level and the MMR immunisation coverage of children who completed their MMR immunisation.
|Number of children||62,699||65,796||66,355||65,509||64,768||62,040|
|MMR dose one coverage||92.0%||92.7%||93.4%||94.0%||94.0%||93.1%|
|MMR dose two coverage||89.4%||88.7%||N/A||N/A||N/A||N/A|
N/A: not available
Coverage by District Health Board (DHB)
Figure 2 presents DHB immunisation coverage by DHB and birth cohort from 2006 to 2011.
It shows that Southern, South Canterbury and Hawkes Bay DHBs have had consistently the highest MMR vaccine coverage and the lowest coverage was found in West Coast DHB.
Figure 2: MMR dose one coverage by birth cohort and DHB (2006 to 2011)
Figure 3 shows the dose two MMR coverage for DHBs. Low coverage is considered to be less than 90% and is noted at Bay of Plenty, Counties Manukau, Lakes, Northland, Waikato, Waitemata and West Coast DHB.
Figure 3: MMR dose two coverage by birth cohort and DHB (2006 and 2007)
Coverage by ethnicity
Table 2 presents national immunisation coverage by prioritised ethnicity of MMR dose one by birth cohort from 2006 to 2011.
|New Zealand European||92.8%||92.7%||92.8%||93.5%||93.3%||92.8%|
Among the 2011 cohort, Asian and Pacific children have the highest coverage (97.0% and 94.9%) for MMR dose one. New Zealand European children achieved 92.8%, children from ‘other’ ethnicities 91.6%, and Māori children have the lowest coverage at 91.2% although from 2006 to 2010, Maori and Pacific coverage was consistently higher than New Zealand European.
Table 3 presents national immunisation coverage by ethnicity of MMR dose two by birth cohort of 2006 and 2007.
|New Zealand European||90.4%||89.9%|
Among the 2007 cohort, Asian, New Zealand European and Pacific children have the highest coverage (90.6%, 89.9% and 88.4% respectively) for MMR dose two. Māori children have slightly lower coverage of 86.7% and children of other ethnicities had a coverage of 85.1%.
Coverage by socioeconomic status
For MMR dose one, there is no significant coverage difference noted by deprivation level (Table 4). However for MMR dose two, coverage decreases with the increase in deprivation level and children living within higher deprived areas (Dep 9–10) have lower coverage rates (88.5%) (Table 5). By monitoring deprivation, general practices are now better able to meet the needs of their community and increase coverage in deprived areas.
|Deprivation index*||Birth cohort|
|Deprivation index||Birth cohort|