By Professor Nigel Brown FRSB, President of the Microbiology Society.
Since 1998 there has been a lot of debate about the safety of vaccination. This originated with a paper that argued that the triple Measles-Mumps-Rubella (MMR) vaccination in infants is related to autism. There have also been statements that vaccines contain toxic compounds and that vaccination overloads the child’s immune system. Such has been the public concern that levels of vaccination have fallen considerably.
These low levels of vaccination have caused problems. In a group that has not been vaccinated, a disease, such as measles or whooping cough, can spread from child to child quite easily. However, if most children are vaccinated, the disease is unlikely to spread. For example, in a class of 40 schoolchildren a 70% vaccination rate means that on average 12 children are not vaccinated and could catch the disease. A 95% vaccination rate means that only two children are not vaccinated and if one falls ill, there are 11 times fewer opportunities to pass the disease on.
The 95% vaccination rate is considered by experts to be the level required to prevent epidemics. This is known scientifically as ‘herd immunity’, although I prefer the term ‘community immunity’. The levels of vaccination against measles in Swansea prior to the 2013 measles epidemic fell below 70%. This was an epidemic waiting to happen. Many children were immunised during the outbreak, bringing levels up to the 95% required for ‘community immunity’.
So why did vaccination rates fall? A paper appeared in The Lancet by Andrew Wakefield and others in 1998 suggesting a link between MMR vaccination and autism. That study has now been shown to be falsified and Wakefield has been struck off the medical register. The paper has been withdrawn by the Editor of The Lancet. It was simply incorrect.
Some people have suggested that vaccines may be toxic, due to the mercury-containing preservative, thimerosal. This is not the case; thimerosal is present now in very few vaccines, and is not toxic at the concentrations used. Others have suggested that the sheer number of vaccinations an infant receives may overload the immune system. This is also not the case; by the very act of breathing, a child inhales many hundreds of things that raise an immune response.
Some people say ‘Measles is not a serious disease’ or ‘Surely it is the right of every parent to decide whether to immunise their child?’. For those who think measles is not serious, read Roald Dahl’s open letter about the death of his daughter from measles. As to parents’ rights, the decision of many parents not to immunise allowed the Swansea measles epidemic. However, there are some people who cannot be vaccinated – very young infants, transplant patients or others on immunosuppressive drugs – they need ‘community immunity’ to protect them, so that it is unlikely that they come into contact with an infected individual. In my view, therefore, it is not just a personal decision to vaccinate your child, but it is a socially responsible one.
Professor Brown FRSB is writing an article each month for The Bridge, a local magazine delivered to every home in the villages of Corsley and Chapmanslade in Wiltshire.
The Royal Society of Biology is sponsoring these articles through our regional grant scheme, which supports locally focussed activity.