In the history of medicine few discoveries have had the impact that vaccination has had. For the sheer number of lives saved, vaccination ranks with clean water: Unicef estimates it saves nine million lives a year. Immunisation has eradicated smallpox and turned once ubiquitous illnesses such as polio into rarities. Despite this, a legacy alternating between complacency and hostility towards immunisation continues to have serious consequences.

Measles is a good example; it is incredibly infectious, with each case leading to 12-18 secondary infections. It is airborne, readily transferable and difficult to avoid. Its effects can be devastating and even fatal, killing 160,000 annually. The vaccine saves more than a million lives a year but, due to the tenacity of measles, the collective resistance of the population has to be high to stop it becoming endemic, so individuals with immunity provide a “firewall”, protecting those who cannot be vaccinated, such as infants. For a disease as virulent as measles, the herd immunity has to be about 94 per cent.



Outbreaks on the rise

Yet this isn’t happening and outbreaks are on the rise worldwide – California and New York are in the midst of their greatest measles outbreaks in decades; and 2011 saw 26,000 cases of measles in Europe, nine deaths and 7,288 hospitalisations. Infections in the UK have surged to 20-year highs. The same trend is evident in Ireland – the 402 cases in 2010 were more than double the 2009 figure. One outbreak in west Cork in 2012 infected more than 50 people, 88 per cent of whom had not received even a single dose of the vaccine. In north Cork, vaccination figures of a shockingly low 26.5 per cent have been reported.

This apathy towards or opposition to vaccination is not solely confined to MMR; cases of whooping cough in Ireland have increased dramatically too, despite a simple vaccine being available. Protection rates this low are courting disaster.

It is unsurprising teenagers have been badly affected: these children were toddlers back in 1998 when the now discredited research from Andrew Wakefield linked the MMR vaccine to autism.

Yet sensationalism sells – by 2002, MMR was the dominant science scare story. Anti-MMR campaigners abounded, and targeted non-science journalists, ensuring their stories were uncritically disseminated and perpetuating the false impression that MMR was dangerous.

This had tragic consequences; and the un-immunised continue to be the biggest victims of this.

Sadly, much of the opposition to vaccines is psychological in nature – as a 2011 New England Journal of Medicine editorial put it: “the spectrum of anti-vaccinationists ranges from people who are simply ignorant about science . . . to a radical fringe element who use deliberate mistruths, intimidation, falsified data and threats of violence in efforts to prevent the use of vaccines and to silence critics”.

Studies have found anti- vaccination campaigners tend to have traits of denialism, conspiratorial thinking, reasoning flaws, preference for anecdote over data and low cognitive complexity in thinking patterns.

Some of the staunchest opposition comes from the alternative medicine community: a study of Australian homeopaths, for example, showed 83 per cent warned patients against immunisation while peddling useless homeopathic interventions.

Conspiracy theories about vaccination abound, usually claiming it is just a money-spinning tool of “big pharma”, despite the fact most vaccines have low profit margins.

Parents who deny their children appropriate vaccines are putting not only their own children but other vulnerable people at risk. Vaccination has saved countless lives. Let us not take that for granted.



Dr David Robert Grimes is a science writer and physicist at Oxford University. He blogs at davidrobertgrimes.com