At some point in history vaccinations became politically divisive.

I’m not sure exactly when that happened, but it must have been sometime after American physician Jonas Salk invented the polio vaccine in the 1950s, because at that time, people seemed to have no qualms about lining up themselves and their children for injection.

Salk so believed in his experimental creation that in 1953 he bravely tested the so-called “killed-virus vaccine” on himself and his family. Then just one year later he tested it on 1.6 million children in Canada, Finland and the United States.

It worked.

Salk understood the importance of equitable access to his vaccine, and he believed elimination efforts would not work without universal low- or no-cost vaccines.

Parents so feared the highly infectious disease that was leaving so many young children paralyzed or worse that they didn’t question the vaccine. By 1957, annual cases of polio dropped from 58,000 to 5,600, according to a polio history on the World Health Organization web site. By 1961, incredibly only 161 cases remained.

I, too, was vaccinated against polio, but not with an injection. I was the first in my family to receive the live-attenuated vaccine that was given orally on a sugar cube.

As a young child I remember comparing my upper arm, sans the round scar, to everyone else in my family — and feeling somehow left out. My mother often has joked it was devouring that vaccine-soaked sugar cube that triggered my fierce sweet tooth and sugar cravings that I still have today.

Apparently, Americans aren’t quite as dedicated to the idea of vaccinations anymore.

Vaccination rates for U.S. kindergartners dropped last year, triggering growing concern among medical experts.

The Associated Press reported last week that usually 94 percent to 95 percent of kindergartners are vaccinated against measles, tetanus and certain other diseases. But those vaccination rates dropped below 94 percent in the 2020-2021 school year, during the first year of the COVID-19 pandemic.

A Centers for Disease Control and Prevention study released Thursday found rates dropped again in the 2021-2022 school year, this time to about 93 percent.

The pandemic disrupted vaccinations and other routine health care for children, and also taxed the ability of school administrators and nurses to track which children weren’t up-to-date on shots.

But that’s not the only reason. CDC officials believe decreased confidence in vaccines is another likely contributor to the vaccine declines.

Public schools typically require vaccinations as a condition of attendance, though some exemptions are allowed. Such exemptions were up slightly last school year, the AP reported.

The new numbers suggest that as many as 275,000 kindergartners lack full vaccine protection.

Falling vaccination rates open the door to outbreaks of diseases once thought to be in the rearview mirror, experts say. They point to a case of paralytic polio reported last year in New York, and to recent measles surges in Minnesota and Ohio.

Those outbreaks coincide with anecdotal and survey information suggesting more parents are questioning bedrock childhood vaccines long celebrated as public health success stories.

An analysis of 2021-22 estimated kindergarten vaccination coverage by state is listed on the CDC’s web site. It includes a look at measles, mumps and rubella; diptheria, tetanus and acellular pertussis; polio; and chickenpox vaccines.

Polio, for example, has a 93.5 percent national estimate.

In Ohio, known as a red state politically, only 88.9 percent of kindergartners are vaccinated against polio.

In neighboring Pennsylvania, a more blue state, 95.1 percent of kindergartners are vaccinated.

In California, also consistently a blue state politically, 96.2 percent of kindergartners are vaccinated against polio.

In New York, also blue, 97.4 percent of kindergartners are vaccinated against polio.

But in Florida, notoriously red, polio vaccination rate is at 91.7 percent.

The trend seems to remain consistent, according to the chart, when comparing other vaccines.

Of course it’s no secret that the political divide was equally apparent in COVID vaccination rates.

And while I’m unsure exactly why that is, I doubt the gaps in vaccination rates between Republicans and Democrats will disappear anytime soon.

Linert is editor of the Tribune Chronicle and The Vindicator.

blinert@tribtoday.com