Dr Catherine Conlon: Why vaccination against measles is so important
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The combination of a fall in the uptake of the measles vaccine combined with measles outbreaks being reported in a number of countries including Austria, the US, and South Africa has led to the HSE urging parents to make sure their children are up to date with their MMR vaccines, particularly before they travel abroad during the easter or summer break.
HSE Immunisation Lead and Consultant in Public Health Medicine, Dr Lucy Jessop, said that the uptake of the second dose of MMR in Ireland for children for the 2020/2021 school year was 88%. "This is down from 91% reported for the 2019/2020 school year. Both of these uptake rates are well below the 95% uptake rates recommended by WHO to stop measles transmission and indicate gaps in immunity."
The drop in vaccination rates was likely linked to disruption to schooling during the pandemic as well as children staying at home after catching covid. But why is vaccination against measles so important?
Measles is a highly contagious, serious disease. Before the introduction of the measles vaccine in 1963 and widespread vaccination, major epidemics occurred approximately every two to three years and measles caused an estimated 2.6 million deaths a year.
In 2018, more than 140,000 people died from measles — mostly children under the age of five, despite the availability of a safe and effective vaccine. Transmission is normally through direct contact and through the air. The virus infects the respiratory tract, then spreads throughout the body.
The first sign of measles is usually a high fever, which begins about 10 to 12 days after exposure to the virus and lasts four to seven days. This can be accompanied by a runny nose, cough, red watery eyes and small white spots inside the cheeks. After several days, a rash erupts usually on the face and upper neck. Over about three days the rash spreads, eventually reaching the hands and feet. The rash lasts five to six days and then fades.
Most measles-related deaths are caused by complications associated with the disease. Serious complications are more common in children under the age of five, or adults over the age of 30.
The Centre for Disease Control and Prevention (CDC) report that ear infections occur in about one in every 10 children with measles while diarrhoea is reported in less than one in 10 cases. Some people may suffer from severe complications such as pneumonia and encephalitis (swelling of the brain).
The CDC report that about one in five unvaccinated people who get measles are hospitalised, one in 20 children with measles get pneumonia, the most common cause of death from measles in young children.
About one child out of every 1,000 who get measles will develop encephalitis that can lead to convulsions and result in deafness or intellectual disability. Nearly one to three of every 1,000 children who become infected with measles will die from respiratory and neurologic complications, the CDC reports.
Measles may cause pregnant women who have not had the MMR vaccine to give birth prematurely or have a low-birthweight baby.
Subacute sclerosing panencephalitis (SSPE) is a very rare but fatal disease of the central nervous system that results from a measles virus infection acquired earlier in life, generally developing seven to 10 years after a person has measles, even though the person seems to have fully recovered from the illness.
Unvaccinated young children are at highest risk of measles and its complications, including death. Unvaccinated pregnant women are also at risk. Any non-immune person (who has not been vaccinated or was vaccinated but did not develop immunity) can become infected.
Measles is one of the world’s most contagious diseases. It is spread by coughing and sneezing, close personal contact or direct contact with infected nasal or throat secretions. The virus remains active and contagious in the air or on infected surfaces for up to two hours. It can be transmitted by an infected person from four days before to four days after the rash appears.
There is no specific antiviral treatment. Routine mass vaccination for children is a key public health strategy to reduce global death rates. The measles vaccine has been in use for nearly 60 years. It is safe and effective.
In Ireland, the measles vaccine is incorporated with mumps and rubella vaccine. It is equally safe in the single or combined form.
Vaccination has had a major impact in reducing measles deaths. From 2000 to 2018, the WHO estimates that measles vaccination prevented 23.2 million deaths. In real terms, global measles deaths have decreased by almost three quarters (73%), from 536,000 deaths in 2000 to 142,000 deaths in 2018.
Without sustained attention, hard-fought gains can be easily lost. Where children are unvaccinated, outbreaks occur. Because of low coverage nationally or in pockets, multiple regions were hit with large measles outbreaks in 2018, causing many deaths.
Based on current trends of measles vaccination coverage and incidence, the WHO Strategic Advisory Group of Experts on Immunisation (SAGE) concluded that measles elimination is greatly under threat, and the disease has resurged in a number of countries that had achieved, or were close to achieving, elimination.
No child should die from measles.
"A booster dose is offered by HSE school vaccination teams when children are in Junior Infants. If a child has missed their MMR vaccines it’s not too late to get protected," said Dr Jessop.
"Parents should enjoy their time abroad but please don’t get ill with measles or bring it home," she concluded.
With summer rapidly approaching, the country will fill with tourists from countries across the globe. Measles outbreaks have occurred in Austria, the US, South Africa and Nepal in 2023.
"The measles virus will always find unvaccinated children," said Henrietta Fore, UNICEF executive director. "If we are serious about averting the spread of this dangerous but preventable disease, we need to vaccinate every child, in rich and poor countries alike.
"The only protection against measles is vaccination. Two doses of MMR vaccine are needed and if a child is not fully protected then MMR vaccines can be obtained from your GP or travel health clinic."
- Dr Catherine Conlon is a public health doctor in Cork and former director of human health and nutrition at safefood