A persistent and pernicious infection is tearing through America as the new year dawns. But it’s not called delta or omicron. It’s not caused by a virus. And it cannot be prevented by wearing a mask or standing 6 feet away from the next customer at the grocery.

This plague is an epidemic of error, an infection of information — or rather, disinformation — and it’s not spread casually or accidentally. It’s being transmitted deliberately and cynically. And it’s crippling our ability to confront two lethal threats to our national health: one medical, the other political.

The first threat comes from the rapidly mutating COVID-19 virus and the adamant refusal of a militant minority to get vaccinated. According to the Centers for Disease Control and Prevention, only 62% of all Americans and 73% of adults are fully inoculated, and the biggest reason for the resistance is a shadowy conspiracy of confusion that turns reality on its head.

Vaccines are dangerous, goes their mendacious message, when the exact opposite is true. Avoiding a jab is far riskier than getting one. As President Biden put it recently, “Almost everyone who has died from COVID-19 in the past many months has been unvaccinated.”

Yes, Donald Trump pushed hard for the development of those vaccines, and has even urged his followers to get immunized, but he still bears a huge responsibility for this miasma of misinformation.

For months, he fostered the falsehoods that the virus would disappear with the changing seasons, that quack cures could work, that medical experts couldn’t be trusted. No wonder his own followers booed him recently when he promoted vaccinations. And no wonder the resistance to scientific evidence falls heavily along partisan lines.

“Republicans make up an increasingly disproportionate share of those who remain unvaccinated, and political partisanship is a stronger predictor of whether someone is vaccinated than demographic factors such as age, race, level of education or insurance status,” reports KFF, an authoritative science news service. “These results suggest substantial challenges for any efforts to further increase vaccine uptake among U.S. adults.”

The second threat from the plague of propaganda is political: the Big Lie that the election of 2020 was rigged by the Democrats and stolen from Trump. He continues to perpetuate his deceit at every opportunity, and his followers have embraced it enthusiastically.

In the latest Washington Post poll, 58% of Republicans say Biden was “not legitimately elected,” while 62% maintain — with no proof of any kind — that there is “solid evidence” to support Trump’s cries of fraud.

“There’s a very sophisticated infrastructure of disinformation by design — including both right-wing TV and social media rabbit holes — so if people want to live in this narrative, they can, very happily,” writes CNN’s Donie O’Sullivan.

Rep. Adam Kinzinger, a dissident Republican who has broken with Trump, says of that infrastructure, “The thing that’s most concerning is that it has endured in the face of all evidence. I’ve gotten to wonder if there is actually any evidence that would ever change certain people’s minds.”

The implications of this insanity are enormous. It leads more than half of Republicans to tell CBS that the violent insurrectionists who stormed the U.S. Capitol last Jan. 6 were “defending freedom.” And it justifies a concerted effort by Republican state legislatures across the country to weaken the safeguards that prevented Trump and his followers from perverting the democratic process a year ago. Election officials who believe in the rule of law are being replaced by toadies who believe in the rule of Trump.

Distributing the disease of disinformation is nothing new for Trump. He entered public life telling a lie: that Barack Obama was not born in the U.S. During his campaign, and then from the White House, he became a super-spreader of untruths while trying to undermine and discredit every individual or institution that tried to hold him accountable — from journalists, judges, intelligence analysts, scientific advisers and — ultimately — his own attorney general and vice president.

He became the Lord of the Lies, leading Rep. Liz Cheney, the conservative Republican from Wyoming, to warn on Twitter: “The Republican Party has to make a choice. We can either be loyal to our Constitution or loyal to Donald Trump, but we cannot be both.”

Democracy can only function if it bases decision-making on a common set of facts, a shared understanding of reality. The epidemic of error is already eroding the foundation of that system.

 Steven Roberts teaches politics and journalism at George Washington University. He can be contacted by email at stevecokie@gmail.com.