AYA Column by Marit van Gils

Every other week, AYA members will share their insights in the world of academia.
Marit van Gils
06/09/2019
Marit van Gils
06/09/2019

The downfall of success; the story of the measles vaccine

The story of the smallpox vaccine best illustrates the success of vaccines. This was the first vaccine, discovered in 1796 by Edward Jenner, and resulted in the eradication of the smallpox virus in 1980 due to high vaccine coverage. Hoping to replicate this success, great efforts and progress have been made to also eradicate other diseases through vaccination, such as polio and measles. Yet, everybody has read the stories about the rise of measles, seen the contradicting statements on vaccine safety, and had emotional debates about whether we should vaccinate. Everybody has the right to choose whether or not to vaccinate; this is the privilege of living in an era of great medical progress and concerns our rights of autonomy and self-determination. These rights should greatly be respected. However, self-determination will only work when all facts are clear, fake news is marked as such and questions are taken seriously. But why should we worry about measles?

Vaccine hesitance is dominated by the persistent belief that a link exists between the vaccine and severe side effects such as autism, despite this link being refuted by a body of evidence from at least 4 independent studies with a total of over one million children. Yet, vaccination hesitance relies on more arguments than just that one. There is a growing popular belief that undergoing childhood diseases would be beneficial. A couple of days of fever, coughing and rashes, it is believed, would make you stronger and this effect could not be achieved by a vaccine. Again, this belief is not based on science, as science has shown that vaccination provides the same immune responses and protection against new measles viruses as being ill, without the negative effects of being ill. And we should not forget, as many seem to do, that this is really not an innocent disease. 1 in 5 patients end up in hospital, 1 in 20 get pneumonia, 1 in 1000 develop encephalitis that could lead to convulsions and can leave the child deaf or with intellectual disability. But there are also other consequences of measles which are often not mentioned and which I believe will show the real importance of measles vaccines.

Have you ever heard of subacute sclerosing panencephalitis? It is a progressive neurological disorder caused by the measles virus. It occurs on average 7 years after the infection with the virus in 1 in 1000 to 10,000 measles infected people, especially babies. No cure exists and the condition is almost always fatal in on average 2-3 years after the start of symptoms. Still, you could argue that the risk of this is very low, but there is one final blow the measles gives us. The virus preferentially infects cells of our immune system and kills these cells. This itself is not a major problem as the body can easily replace these cells, similar to healing a cut in your skin. But the venom is the killing of cells we call immunological memory. These cells are responsible for protecting us from diseases we have encountered in the past, including vaccines mimicking this. As a consequence, measles infection increases overall childhood infectious disease morbidity and mortality. In other words, measles infected children have a higher risk of getting seriously ill or even die from other infectious diseases for up to 30 months after a measles infection compared to measles vaccinated children and this happens in everyone who catches a measles infection.

Turning this around, measles vaccines have increased the success of other vaccines and sustained the protection against previously encountered diseases. Any parent will remember the numerous illnesses their children have had in the first years. By not getting their child vaccinated against the measles, parents will not only take the risk of hospitalization, pneumonia, deafness and neurological disorders affecting their child but also the risk of going through more childhood diseases after the infection, with additional risks of morbidity and mortality, and of catching diseases for which the child was vaccinated in the past. We could say the measles vaccine together with other vaccines have dug their own graves because we forgot how severe childhood diseases can be since we never encounter them due to the success of vaccines. This may change with the decline in (measles) vaccine coverage, but hopefully we will not let the diseases win.