After the recent warning distributed by the Health Service Executive (HSE) to Dublin universities about mumps outbreaks, a conversation around vaccines is once again taking place. Mumps is a serious disease that can cause deafness in children, infertility and even death. Aside from this, many students receive vaccinations during their time at college, whether it is required for their course, a precaution before a trip abroad or protection against a disease that is circulating at home. It is therefore unsurprising that many have questions – as well as some misconceptions – surrounding vaccines.
The recent mumps outbreaks across Ireland, and indeed Trinity, have led many to question the efficacy of the Measles, Mumps, Rubella (MMR) vaccine. But the reason for the virus’s recent outbreaks is, in fact, largely due to low vaccination rates in the original outbreak areas. Low vaccination rates lead to a loss of “herd immunity”, which prevents the spread of disease. If a high enough portion of people in a given population are immune to a disease, it is not able to spread very well and may eventually be eradicated entirely, as smallpox was in the 1970s.
Herd immunity is especially important for viral infections, such as mumps or influenza, as viruses can only survive and replicate within the cells of a host. Of course, lots of people wonder how it’s then possible that people who have had their two MMR vaccinations can still contract the virus in question at all. Well, vaccinated individuals are highly unlikely to contract the virus, but it’s still possible if they have been in close contact with someone who has the disease. If they do end up getting sick, their symptoms will be much less severe than those of an unvaccinated person.
To many healthy people, the flu seems more of a burden than a serious threat and so many decide not to pay for the flu vaccine that may or may not even protect them
It’s important to remember, however, that if enough of the population were vaccinated for herd immunity to kick in, these outbreaks would not happen at all. Vaccinated people would then be completely safe from the mumps infection. Those who refuse to vaccinate, therefore, put the entire population at a greater risk. Viral infections like to mutate, which means that they change their genetic makeup, potentially giving them new abilities. If mumps continues to spread, it is only a matter of time before a mutation arises, which gives the virus an ability to be unaffected by the powerful immune response against it that is present in vaccinated individuals. In this case, a whole new vaccine would have to be created.
The efficacy of vaccines should not be disputed, yet it often is. In the vaccine conversation, one of the most common statements I hear goes something along the lines of “I got the flu vaccine last year and still got the flu”. While some might take this as proof that the vaccine is not effective and some defenders of vaccines may dismiss this statement as false, it is in fact true that you can still contract the flu when you have received the flu vaccine. Naturally enough, people might then ask: “Why take a vaccine that doesn’t work?” To answer that question, we first need to understand the influenza virus itself. There are three groups, or “genus”, of influenza that infect humans. Within one of these groups there are about eleven variations, or “serotypes” of the virus. Each of these variations is recognised by our immune system as completely separate pathogens, which makes vaccinating against the flu particularly tricky.
When flu season comes around, the vaccine that is distributed is intended to protect against what the World Health Organisation (WHO) predicts to be the three main circulating variations of the virus that year. This is why its effectiveness varies, and why those vaccinated can still be infected from other types of flu virus that are circulating. However, if the vaccine was well matched to the main circulating variation of that year, many people will be protected.
It’s important to remember, however, that if enough of the population were vaccinated for herd immunity to kick in, these outbreaks would not happen at all
A follow-up question to this is often: “In that case, why bother with a vaccine for the flu anyway?” To many healthy people, the flu seems more of a burden than a serious threat and so many decide not to pay for the flu vaccine that may or may not even protect them. But some groups, such as the elderly, receive the flu vaccine for free, as they are at a higher risk of suffering from serious complications, or even death, as a result of the flu. It is therefore strongly recommended to get vaccinated if you are in contact with any of the at-risk groups: the idea is that you receive the flu vaccine to help protect the most vulnerable.
New flu vaccines are constantly being developed, as it is known to be a virus that mutates rapidly. There is a lot of work being put into development of a universal flu vaccine that would protect against all variations of the virus. If enough of the population received this vaccine, the flu virus would no longer be able to spread and mutate further to protect itself against the vaccine.
So next time you receive a vaccine, as you brace for the sting of the needle, take solace in the fact that you are not only protecting yourself, but playing your part in protecting the whole population, especially those most vulnerable to disease. It might just make that little pinch a little more bearable.
