Community immunity as a social contract against disease

Membership in community organizations is dropping and people are seeing each other less and less, according to Robert D. Putnam, in his book Bowling Alone.

“There are fewer and fewer of us meeting our neighbors, socializing with other members of the community or socializing outside of the family. Television, internet and texting detaches us from speaking to one another.”

Societal problems can arise from declining socialization, and this “every man and woman for themselves” approach has potentially tremendous effects on public health. Keeping communities healthy and free from viral disease relies in large part on the success of immunity of the overall community.

This principle of Community Immunity rests upon the idea of safety in numbers. If more people are immune to a certain virus, either through vaccination or through already having the disease, then more people in the community, even if they themselves aren’t immune, are protected from the disease.

In our last article, we touched on the concept of community immunity, or herd immunity, as impacted by vaccine compliance. Today we will expand on the concept of herd immunity and discuss why 85 to 90 percent vaccine compliance amongst a community is really a social contract we have with one another against disease.

Herd immunity is defined as the means of protecting a whole community from disease by immunizing a critical mass of its populace, according to Willingham and Helft, in a 2014 posting on NOVA. The concept being that a vaccine protects more than just the vaccinated person. It can, in sufficient numbers, protect a community from the transmission of vaccine-preventable diseases.

However, all diseases are not created equal. Measles, for example, is a communicable disease transmitted through the air that has a higher immunity threshold because it is highly contagious, requiring a 95 percent herd immunity rate within a community. While polio, with a somewhat lower immunity threshold, requires an 80 to 85 percent compliance rate for effectiveness.

Another consideration is the age of the most vulnerable population. With pertussis – or whooping cough – our most vulnerable population is our precious babies who lack protection when too young to begin their own immunization. In these cases, a cocooning protection occurs from immunized community members and provides protection to our babies through sheer numbers of protected individuals against the disease.

Consider this illustration: Let’s look at a bowling alley where people are bowling by themselves. In the first lane is a guy who contracts influenza, and he passes it along to the woman in the second lane. If that woman isn’t immune to influenza, then the disease will likely continue its path, lane by lane, until every person in the bowling alley has contracted influenza.

But if that woman is immune, then the disease stops with her, because the virus has nowhere else to go (assuming the guy in our example had no contact with anyone else). By her immunity, she protected all the people in the subsequent lanes, even if they did not get a flu shot.

As each one of us immunizes for our own protection, we then protect the larger community as well. Similarly, we share the benefit of our waters, clean air, safe roadways, fire and police protection, our schools, our laws and our voices. Protection of the very young, the very old and those with compromised immune systems due to disease are part of our protection as well, making herd immunity in sufficient numbers an imperative.

There is a saying in public health: A major disease disaster is only a plane ride away. No saying was ever truer, as we have become a more mobile society, traversing our country and our world on a daily basis. No longer are we protected by a small and limited society as we encounter individuals from places near and far making diseases closer to us than ever before.

If you have more questions or would like more information, please contact your Mat-Su Public Health Center at 352-6600.