MANY PARENTS worry about the safety of the standard childhood vaccinations recommended by the health services. Of most concern is generally the safety of the three-in-one vaccination against measles, mumps and rubella (MMR). However, studies attest to the safety of these vaccinations and also show that unvaccinated children are at risk of contracting serious diseases, such as measles. The medical profession should become more proactive in promoting this message.
A significant minority of parents believe vaccinations can induce serious side effects, and either do not bring their children for the full range of recommended vaccinations or delay the timing of them. Some also think, because certain diseases such as polio, measles and tetanus are rarely seen nowadays, their children are not at risk. Others believe certain diseases prevented by vaccine, such as chicken pox and measles, are not serious. Each of these three beliefs is false, as MF Daley and JM Glanz explained in Scientific Americanlast month, summarising the current situation regarding childhood vaccination.
Apart from sometimes causing mild fevers, there is little evidence that vaccinations cause serious side effects. Fears about vaccines peaked in 1998, when a paper by Andrew Wakefield and others, published in the Lancet, proposed that the measles vaccine could cause autism in susceptible children. This proposal has been thoroughly disproved, and over a dozen studies in the meantime have shown vaccines do not cause autism. The Lancetretracted Wakefield's article in 2010, and he lost his licence to practice medicine.
Preliminary data from Finland and Sweden in 2010 linked a spike of narcolepsy among 4- to 19-year-olds with Pandemrix, a vaccination against swine flu. Swedish data estimated the vaccination might cause three cases of narcolepsy for every 100,000 vaccinations. However, a study published last month in the Annals of Neurology,by Fang Han and others, claims the narcolepsy is triggered by the swine flu infection and not by the vaccine.
The concept of safety is commonly misunderstood by the public. There is no such thing as absolute safety; there is only probability of risk. Vaccinations are not 100 per cent effective: a tiny proportion of people vaccinated against a disease still contract the disease, usually displaying only mild symptoms. It may also be that one in several million vaccinations will induce a serious side effect. It is equally true that the other several million vaccinations will produce no serious side effect but will ensure effective protection against disease. And without a vaccination you are at significant risk of contracting a serious disease.
Daley and Glanz studied hundreds of thousands of children in Colorado. They found that, compared to vaccinated children, unvaccinated children were 23 times more likely to develop whooping cough, nine times more likely to develop chicken pox and 6.5 times more likely to be hospitalised with pneumonia.
One out of 20 previously healthy children who get measles will come down with pneumonia. One out of 1,000 will get inflamed brains that can lead to convulsions and intellectual disability. And one or two out of 1,000 will die. Chicken pox can lead to severe skin infections, swelling of the brain and pneumonia.
In Ireland, the HSE is concerned about the rise of measles. The MMR vaccine is the only protection against measles. In 2000, an outbreak in Dublin saw cases rise to 1,600; three children died. Since the start of 2011, 135 cases of measles have been recorded, over 70 per cent of them in north Dublin city. Of the more than 26,000 cases across Europe, six deaths, 444 cases of severe pneumonia and 14 neurological complications were recorded.
Measles is highly contagious. At present, only 90 per cent of children have received one dose of MMR by the age of two, well below the 95 per cent target necessary to prevent cases of measles and measles spread by contagion.
Prior to developments in vaccines and antibiotics, humankind was completely vulnerable to innumerable diseases. We must not lower the barriers against disease now by adopting a wrong-headed attitude towards vaccination. By avoiding recommended vaccinations, you swap a minuscule risk of a significant side effect for a much larger risk of contracting a potentially fatal disease.
William Reville is Public Awareness of Science Officer and a Professor in the Biochemistry Dept at UCC. See understandingscience.ucc.ie