Weighing up the risk

No decision is risk-free and everything in life carries some level of risk. When parents make the decision about immunisations for their child, they need to weigh up whether the risk of their child catching the diseases and having complications is greater than the risk of potential reactions to the immunisation.

The overwhelming majority of parents believe in immunisation for their children. We have however included here the views of a few parents who do not believe immunisation is right for their own child based on their personal beliefs. Their views represent a small proportion of the population.

In order to make an informed judgment about risk, parents need to be sure that facts which are used to weigh up the risk are based on reliable, scientific evidence and there is now a mass of this information available (see 'Information for making decisions'). 

It is important to know that you are comparing like with like. For instance, comparing the chance of your child developing inflammation of the brain (encephalitis) as a rare complication of measles (1 in 1,000-2,000 cases of infected children - Oxford University - Oxford Vaccine Group June 2019) and the chance of developing encephalitis as a complication of MMR (less than 1 child in a million). 

Deciding that the risk of their child getting the disease was greater 

Parents who decided that the risk of their child getting the disease was greater than the side effects from the immunisation took several things in to consideration:
  • They reviewed the suggestion a link between inflammatory bowel disease, autism and MMR and decided that ithere was not enough evidence, that it was one study based on a biased sample, with tentative findings, where there might have been a conflict of interest, now discredited by most of the team that produced it and by the editor of the Lancet who published the study findings. 
  • They believed the media had exaggerated the risk attached to the immunisation.
  • They considered the risk of other side effects to be very small and not high enough to warrant not giving their child the immunisation.
  • They assessed the chances of their child getting a disease where they lived. For example, if they lived in an area where many people didn't immunise, or if there had been outbreaks of measles or mumps in their neighbourhood, the chance of their child getting one of these diseases was increased.
  • They didn't want these diseases returning in the population and if there were epidemics they believed the risk of catching the disease would be higher for their child.
  • They didn't want their child to be ill when it could prevented.
  • They considered it better to have a short-term risk from a reaction to the vaccine than a long-term risk through childhood of their child not being protected from the diseases.
  • They were concerned that the health care their child might need if they had a complication from measles would not be available.

Deciding that MMR was less risk than single vaccines

Parents who decided that MMR was less of a risk than single vaccines considered the following:

  • Single vaccines were unlicensed in the UK.
  • They were only available in private clinics and they couldn't be sure how trustworthy the clinic was.
  • There would be opportunity for unscrupulous people to set up clinics for single vaccines to take advantage of parents' concerns.
  • Because they were unlicensed they were possibly less reliable and could give less immunity than MMR.

Deciding that single vaccines were less risk than MMR.

One parent we interviewed who decided that single vaccines were a safer option than MMR personally believed that if there was a small but potential risk that her daughter would get a reaction to the MMR, she didn't want to take that risk. She believed that if the vaccines were imported from America or France the risk of them being unsafe was lower. The MMR vaccine also comes from abroad. She also personally believed that going to a clinic in Harley Street would be less risky. 

Deciding that the risk of side effects from the immunisation was greater

A very small number of parents who decided that the risk of potential side effects from the immunisation was greater than the risk of their child getting the disease took several things in to consideration:

  • They personally believed that while these diseases could be unpleasant, they were not particularly serious unless a child developed complications. Around 1 in every 15 children with measles will develop more serious complications which include ear infections, pneumonia and diarrhoea and encephalitis (Oxford University - Oxford Vaccine Group June 2019). They personally believed the chance of a complication occurring to be quite low, so they decided to take a chance that if their child caught the diseases, they wouldn't develop a complication and they would be able to nurse them through the illness (see 'Parents' views of the diseases').
  • They personally believed that the media and the health authorities portrayed these diseases as more serious than they actually were. Before immunisation was introduced, most people who have measles and mumps did not suffer serious complications. Around 1 in every 15 children with measles will develop more serious complications which include ear infections, pneumonia and diarrhoea and encephalitis(Oxford University - Oxford Vaccine Group June 2019). When these rates are applied to the whole population, the complications of measles and mumps caused a serious number of hospital admissions and long-term disability.
  • They believed that it was better to have the disease than be immunised against it and it helped to build up the immune system. Gaining immunity from actually having the disease involves the risk of a child developing a complication.
  • A few of these parents personally believed that building up their child's immune system, through diet and homeopathy, was better than having immunisations. The protection against measles, mumps and the other vaccine-preventable diseases comes from have antibodies (immunity) which is specific for each disease. This specific protection can be produced only if the immune system is stimulated by the vaccine or the natural infection. General measures to strengthen the immune system do not give the protection against the disease and its complications. While it is true that a child with an underlying health condition is more likely to have complications and/or die from measles, healthy children can be very ill too. Allowing them to catch the diseases means that they run the risk of complications.
  • They considered the benefits of immunisation and were unhappy that they didn't give 100 per cent protection.
  • They were unhappy with the ingredients in vaccines and they personally believed that the chance that these might cause a reaction in their child was a riskier option.

Last reviewed August 2019.
Last updated August 2019.


Please use the form below to tell us what you think of the site. We’d love to hear about how we’ve helped you, how we could improve or if you have found something that’s broken on the site. We are a small team but will try to reply as quickly as possible.

Please note that we are unable to accept article submissions or offer medical advice. If you are affected by any of the issues covered on this website and need to talk to someone in confidence, please contact The Samaritans or your Doctor.

Make a Donation to

Find out more about how you can help us.

Send to a friend

Simply fill out this form and we'll send them an email