Vaccine not fully effective, but still the 'best way' to protect against mumps
More than 20 west Aucklanders vaccinated for mumps still contracted the viral illness.
Auckland Regional Public Health Service (ARPHS) confirmed there was a mumps outbreak in the region - 148 cases as of July 7, with 82 of those cases from west Auckland.
Of the 82, 24 were fully vaccinated with the measles, mumps and rubella (MMR) vaccine.
ARPHS clinical director Dr Julia Peters said MMR was 88 per cent effective at preventing mumps.
"So a small number of people may still get the disease, even if they have been vaccinated," Peters said.
"Furthermore, some people who have received MMR may have waning immunity after about 10 to 20 years, meaning they may still catch the mumps infection when they are older."
She said 58 of the people who became ill in west Auckland were not fully vaccinated with the MMR vaccine.
Peters said 44 of those who had fallen ill were Pacific Islanders. Mumps cases among Samoans numbered 24, with 21 Maori people also contracting the viral illness.
The suburb of Massey recorded the highest number out cases with 31, Henderson had 17 cases of mumps and Ranui 11.
12 west Auckland schools had reported 40 cases of mumps.
Peters said getting vaccinated was still the "best way" to protect against mumps.
Vaccinated people who became ill with mumps were also likely to suffer less severe complications of the infection, she said.
"The MMR vaccine has an excellent safety record.
"Side effects are few and usually mild in comparison to the serious consequences of having measles, mumps, or rubella."
The MMR vaccine was introduced in New Zealand in 1990. It is routinely given at age 15 months, and again at four years.
Before MMR Peters said there were large outbreaks of mumps every three to four years.
The last epidemic was in 1994.
"To prevent mumps outbreaks, a high proportion of the population, that is at least 92 per cent, needs to be fully immune."
Peters said majority of Auckland's mumps cases were in the 10-to-29 age group, part of an age group the National Immunisation Register (NIR) did not have vaccination data for.
NIR collects vaccination information on all children born only from 2005 onwards.
"The NIR does not have vaccination data for young people aged 12 years and above.
"The current outbreak suggests there is a relatively high proportion of 10-29 year olds who are not fully immune."
Peters said people needed to check with their doctors if they have been vaccinated, or needed to catch up with a second dose of MMR.
Children who were at close contact with a mumps case were eligible to receive their first MMR vaccine at 12 months during an outbreak, and receive a second dose four weeks later.