Contents

11 Measles

11.3 Epidemiology

11.3.1 Global burden of disease

Mortality

Measles is the most common vaccine-preventable cause of death among children throughout the world. The disease is highly infectious in non-immune communities, with epidemics occurring approximately every second year.

In 2000 the estimated global measles mortality was 535,000 deaths (95% CI: 347,200–976,400). In 2008 all WHO member states endorsed a target of a 90 percent reduction in measles mortality by 2010, compared to 2000 levels. By 2010 the global measles mortality had decreased by 74 percent to 139,300 (95% CI: 71,200–447,800). India accounted for 47 percent of estimated measles mortality in 2010, and the WHO African region accounted for 36 percent.5

Measles elimination

Indigenous cases of measles, mumps and rubella have been eliminated from Finland over a 12-year period using a two-dose measles, mumps and rubella vaccine (MMR) schedule given between 14 and 16 months and at age 6 years.6 The WHO region of the Americas eliminated indigenous transmission of measles in 2002.7

In October 2005 the Regional Health Assembly of the Western Pacific Region of WHO endorsed a target that by 2012 measles would be eliminated from the Western Pacific Region. In 2012 measles incidence in the region declined to a record low of six cases per million population.8 As at March 2013, 33 out of 37 countries may have interrupted endemic measles virus transmission,9 meaning that the virus cannot spread within the population (unless it is imported).

In May 2012 the 194 member states of the World Health Assembly endorsed the Global Vaccine Action Plan 2011–2020,10 which aims to eliminate measles in at least four WHO regions by 2015 and in five WHO regions by 2020.

11.3.2 New Zealand epidemiologyTop

Measles vaccine was introduced in 1969 and moved to a two-dose schedule (as MMR vaccine) in 1992. Measles became a notifiable disease in 1996. The current two-dose schedule at ages 15 months and 4 years was introduced in 2001 (see Appendix 1 for more information about the history of the Schedule).

The most recent measles epidemics occurred in 1991 (the number of cases was estimated to be in the tens of thousands – although hospitalisation data does not support this figure) and 1997 (2169 cases identified).

Smaller outbreaks continue to occur, the most recent in 2009 (248 cases notified, 205 of which were due to three outbreaks) and 201111 (597 cases notified, 560 of which were due to six outbreaks). The largest outbreak in 2011 mainly affected Auckland, with 489 confirmed or probable cases. It started with an unimmunised child, who became infected on a family trip to England, then developed measles when back in Auckland. Many of the secondary cases were in unimmunised school children. The outbreak officially ended in July 2012.12

In 2012, 68 cases of measles were notified (1.5 per 100,000) and 55 (80.9 percent) were laboratory confirmed. This was a significant decrease from 2011 (597 cases; 13.6 per 100,000). Of the 68 cases, 57 (83.8 percent) had a known vaccination status. Of these, 40 were not vaccinated, including 20 cases aged under 15 months (not eligible for the first dose of MMR vaccine). Ten cases had received one dose of vaccine and seven cases had received two doses.13

Measles cases significantly decreased again in 2013, with four hospitalisations (20 hospitalisations in 2012), eight notifications and three laboratory-confirmed cases.

Figure 11.1 shows hospital discharges, notifications of measles and laboratory-confirmed cases.

Figure 11.1: Hospital discharges from measles, 1970–2013, notifications, 1996–2013, and laboratory-confirmed cases, 1984–2013

Figure 11.1: Hospital discharges from measles, 1970–2013, notifications, 1996–2013, and laboratory-confirmed cases, 1984–2013

Source: Ministry of Health and the Institute of Environmental Science and Research

To eliminate measles epidemics, modelling suggests that New Zealand needs to achieve a coverage level of greater than 90 percent for both doses of MMR.14 If this coverage level is achieved and maintained, the length of time between epidemics will increase and may lead to the elimination of measles.