How herd immunity is protecting you and your child and why you should be concerned if you rely on herd immunity

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How’s THAT for a title? Catchy, right?

More and more I hear people ask, ‘why is my unvaccinated child a risk to your vaccinated child if vaccines are so good?’

Here’s the thing. Vaccines are fantastic, but none of them is a 100% guarantee against illness all on its own. For example, the efficacy of the MMR vaccine is approximately 97%. It’s an extremely effective vaccine and does a great job of directly protecting those 97% of people. But what about the other 3%?

Simple – herd immunity! The MMR vaccine is given to a high enough percentage of the population that it provides wide protection for those 3%. With high enough participation, there are fewer doors for things like measles and mumps to get through and find a foothold in the population, so those 3% benefit from the mutual participation of their community and are kept safe by the shared general interest in not having a measles outbreak.

What happens as participation drops?

Here’s the problem. Those members of a community who have previously not been protected by everyone else’s immunity begin to lose the walls that keep these diseases away from them. This includes people who have failed to develop their own immunity from their own vaccine (3% in the case of MMR) and people who have not participated in vaccination are at higher risk. There is no natural immunity to measles, for example, without getting the measles. Our natural immune systems are great, but before they have learned to fight a particular disease they are vulnerable. Members of higher risk groups (young children, pregnant women, the elderly, and people with underlying health issues) have an increased vulnerability and are more susceptible not only to contracting these illnesses, but to suffering much more serious consequences from them.

This is why members of our communities who opt against vaccine participation have an effect on their communities. If every vaccine were 100% effective, then those who opt out would be choosing only to impact their own chances of contracting illness, without affecting anyone else around them. But that is not the case, and so every time someone chooses not to vaccinate, they’re essentially choosing not to put up a wall against an illness that will affect their own health and the health of their family, and providing a door for it to come in to the general population.

Let’s apply this to influenza. As we all know, influenza is an unstable disease. What this means is that it mutates quickly enough that a strain will look different from one year to the next, making vaccine creation a new challenge with each flu season. I’ve recently seen some misunderstanding about how they create each year’s flu shot, most commonly a belief that they simply use the previous year’s strains. This would be ineffective, and this is not what they do. In reality there are dedicated teams who closely monitor global flu patterns throughout the year and watch the way they grow and change to prepare for what they might look like when they arrive in a region. The CDC offers a fuller explanation. Because we can’t know definitively how influenza will look each year before it arrives, it takes a lot of careful work to anticipate the presentation of strains and work from there. Efficacy for the flu shot typically averages around 50-60%, though some years have a fantastic match and others have a poor one, based on the way the strains mutate between vaccine production and the start of flu season.

Because we don’t have influenza in check, and because it isn’t possible to get it in check at this point in time with a universal vaccine (one is in the works, and may be available for influenza A within five to ten years), it also isn’t possible to achieve participation that will result in herd immunity. What we can achieve, though, is a greater number of walls providing our communities and the more vulnerable members of our communities with a greater chance of avoiding contracting these infectious diseases.

Do you have high risk people in your community? A pregnant coworker? A child with a health issue that may compromise his or her immune system? A friend with a heart condition? Elderly neighbours? Your participation in vaccination and other infectious disease prevention might be the wall that stops an infectious disease from reaching that person and putting them at risk for a serious illness that they might be unable to fight. And your neighbour, coworker, or friend getting their vaccinations might be the walls that protect you and your family.

As the movement against vaccination picks up more steam, and more people reject the overwhelming evidence that a vaccinated population is healthier than an unvaccinated one, we put our more vulnerable members of our population at greater risk. This means that unvaccinated children who were previously benefiting from their community’s vaccination choices are left with fewer walls to protect them, and the greater number of unvaccinated members of our community also increase the risks of infection for the general population. These are the conditions that open doors to outbreaks and epidemics.

If you have opted against vaccination I encourage you to speak with your doctor about any concerns you might have with regards to vaccines, and aim for high standards when looking for information online. Insist on science over anecdotes, and look at what you’re reading objectively. Avoid echo chambers and seek out facts. Understand the terminology and understand what VAERS data really is. If a doctor has been discredited after having produced fraudulent work as fact, and his claims have never been proven by any scientific study, look instead for solid peer-reviewed studies, and trust that your own physician has dedicated his or her life to keeping you healthy.

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