They gathered in the cold, carrying signs and grudges. One sign read: “Vaccines: the more you KNOW, the more you NO!”

With a measles outbreak among unvaccinated children in the Vancouver area causing Washington Gov. Jay Inslee to declare a health emergency last month, hundreds of protesters turned out at the state capitol in Olympia to oppose a bill that would restrict personal exemptions to vaccines for school-age children.

So-called “anti-vaxxers” are part of a homegrown fringe movement, one that is suspicious of scientific data about the safety and efficacy of vaccinations. But they unwittingly have been getting overseas help in recent years.

Russian President Vladimir Putin isn’t trying to mess only with America’s elections. He has set loose his undercover opinion manipulators to promote fear of vaccines and set pro- and anti-vaccination Americans against one another, a recent study concluded.

The overarching objective in this ongoing offensive: to divide and terrify Americans -- and win a second Cold War.

For the most part, Russia has taken this fight to where we live: on social media.

“Compared with average users, Russian trolls, sophisticated bots and ‘content polluters’ tweeted about vaccination at higher rates,” the study concluded last fall. The research, published in the American Journal of Public Health, found that “[a]ccounts masquerading as legitimate users create false equivalency, eroding public consensus on vaccination.”

An example of a “disinformation” tweet: "Did you know there was a secret government database of #Vaccine-damaged child? #VaccinateUS."

Another tweet argued the other side: “#VaccinateUS You can’t fix stupidity. Let them die from measles, and I’m for #vaccination!”

Both tweets, it appears, came from “bad actors” in Russia.

"By playing both sides, they erode public trust in vaccination, exposing us all to the risk of infectious diseases,” John Hopkins University computer-science professor Mark Dredze told the BBC.

The American Journal of Public Health study linked malicious propaganda on the issue to social-media accounts from Russia’s Internet Research Agency, which Robert Mueller’s special-counsel office has indicted for its role in 2016 election interference.

The U.S., it must be noted, isn’t the only Western country where measles outbreaks have returned in recent years. The BBC reports that higher rates of measles are being found throughout Europe as well.

-- Douglas Perry