The Importance of Community Immunity

This blog post is adapted from our Parents’ Guide to Children’s Vaccines.

You’ve probably heard of community immunity, or “herd immunity,” which means that when the majority of a population is vaccinated, it provides protection to the rest of the population that’s not vaccinated.

Community immunity means that we’re able to protect the most vulnerable populations among us: babies who aren’t yet old enough to get vaccines; senior citizens; people with weakened immune systems; pregnant women; or anyone allergic to a vaccine and unable to receive it.

Vaccines rates + community immunity

Each disease requires a different vaccination rate in order to provide community immunity. For example, for polio, 80-85% of people must be vaccinated in order to provide community immunity.

For measles and pertussis, on the other hand, 90-95% of a population must be vaccinated in order to protect the community.

Regardless of the disease, the vaccination rate of the community must be significant in order to protect the unvaccinated population.

This is one of the reasons that vaccinating yourself and your children is a great way to protect your family’s health — and the health of aging grandparents, neighbors, and little ones.

Setting the record straight on community immunity

Some people misunderstand the idea of community immunity and think that because some of these serious diseases are no longer prevalent in society, it means that we no longer need to vaccinate against them.

community immunity (2).png

Unfortunately, this just isn’t the case. When people choose not to vaccinate and vaccination rates go down, serious diseases reappear in communities again.

A good analogy for this is a community garden, filled with flowers, fruits and veggies. If we all do our part to take care of, water, and weed the garden, it will thrive. But if we decide that we have weeded enough and no longer need to do it, the weeds will eventually sprout up all throughout the garden and threaten the flowers and food.

Just like a garden that becomes overgrown with weeds when we stop weeding, if we stop vaccinating just because we see fewer instances of a disease, the disease will return and cause damage to our community.

The story in our communities

In Oregon and Washington, we’ve seen this happen firsthand. As of March 22, there have been 74 confirmed cases of measles in Washington this year, and 10 confirmed cases in Oregon (four of which are linked to the Clark County, Washington outbreak). Whereas measles had previously been considered eliminated from society, the disease has reappeared in recent years, primarily in communities with higher rates of unvaccinated people. (For further reading, see our post on how to protect your infant or young child from the measles outbreak.)

For some diseases, Oregon’s vaccination rates fall short of the 80-95% threshold for community immunity. In fact, in some schools, only about 20-60% of children are fully vaccinated.

Low vaccination rates pose a serious risk to our state’s most vulnerable populations.

The good news is that when you choose to vaccinate, you’re not only protecting your family’s health, but also boosting community immunity and protecting the community in which you live.

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