NEWS FOCUS:The measles epidemic is being driven by a failure to vaccinate
THE MEASLES virus is re-emerging in Europe, and officials in Ireland are urging parents to ensure their children get both doses of the MMR vaccine.
For many, the word “measles” conjures up an image of the characteristic rash an infection brings. But for a small number of people, an infection can result in far more serious complications, such as pneumonia or encephalitis, and it can even kill.
And with measles currently resurging in various parts of the world, officials are urging more widespread vaccination to curb its spread.
Vaccinations had been dampening down the virus, explains Diane Griffin, who is Alfred and Jill Sommer professor and chair in Molecular Microbiology and Immunology at Johns Hopkins University Bloomberg School of Public Health.
“There had been dramatic decreases in cases of measles associated with initiatives to improve measles vaccination worldwide,” says Prof Griffin, who was in University College Dublin earlier this month at a meeting of the Global Virus Network.
“That was mainly reflected in Africa, where there was a low in 2008 due to the introduction of mass campaigns. But mass campaigns are expensive and there is global pressure on funding – and in 2009 there was a resurgence, which was noticed first in South Africa. By 2010 there were tens of thousands of cases.”
An ongoing epidemic in Europe has France at its epicentre, while the US is “seeing more cases than we have had for a decade” and Canada probably has 10 times more cases [than the US], according to Griffin.
“What is driving this epidemic is the failure to vaccinate,” she says. “Measles control continues to be a problem in both developing and developed countries due to lack of vaccination.”
So what has been happening in Ireland? “We have never had a year without measles,” says Dr Suzanne Cotter, a specialist in public health medicine with the Health Protection Surveillance Centre.
The year 2000 was a particularly bad one with more than 1,600 reported cases of measles in Ireland and three associated deaths, and in 2010, 403 cases were reported, nearly exclusively among non or partially vaccinated children, according to Cotter.
“This year, what is notable is that of the 254 cases reported so far , 220 have been in the Dublin region,” she says. “And what we have identified in the analysis of the data is that it is [in] the children who are unvaccinated predominantly. Some children had one dose of vaccine, and we know that one dose will protect most children but not all children.”
The recommendation in Ireland is to receive one dose of the MMR vaccine at about 12 months of age and then a second dose at about age four to five, typically when the child starts school.
“The second one is not given as a booster to improve the impact of the first one,” says Dr Brenda Corcoran, a consultant in public health medicine and head of the National Immunisation Office in the HSE. “When you give the first measles vaccine to a group of children, about 90 per cent of them will respond to it and you have got 10 per cent you have given the vaccine to but they are not protected. So you give the vaccine again, and 90 per cent of the 10 per cent get protected, so by giving two doses of MMR, 99 per cent of children are protected against measles.”
The rates of uptake for the first MMR dose have generally improved in Ireland, says Corcoran. “When we had the outbreak in 2000, the national uptake rate was 69 per cent,” she said.
“We are now at 91 per cent, which is very good, but it’s still not the 95 per cent, and that is only for the first dose. We need the uptake rate to be 95 per cent for the two doses, otherwise we will continue to have outbreaks .”
An infamous 1998 study led by Andrew Wakefield sparked concerns among parents about links between the MMR vaccine and autism and bowel disease, which had a negative impact on vaccination uptake, says Corcoran. “There’s no doubt that the adverse publicity had a huge impact on the level of uptake of MMR in Ireland and the UK primarily,” she says.
“But you have to remember that the research Wakefield did was on a tiny number of children. It has [since] been totally discredited by the journal and by other research that looked at hundreds of thousands of children, none of whom have had any link between the vaccine and autism or the vaccine and bowel disease.”
The risks associated with the MMR vaccine are “minuscule”, according to Corcoran. “Most will get a sore arm and a small number of children will get ‘mini-measles’, which is not contagious and it shows the vaccine is working.
“If you compare that with the risks of the pneumonias, the neurological [problems] or encephalitis or the other serious complications of measles, there is no contest.”
See immunisation.ie
