Matthew Baum of Harvard found that people in red states were indeed less likely to get vaccinated — and more likely to die of swine flu. In the end, that swine flu outbreak wasn’t as lethal as many had feared, but it still killed or contributed to the deaths of as many as 400,000 people worldwide. In the United States, it infected 60 million people, caused 274,000 hospitalizations and killed 12,469 people, according to the Centers for Disease Control and Prevention.

“As states become relatively more Republican, swine flu-related deaths rise,” Baum wrote in a 2011 article in The Journal of Health Politics, Policy and Law.

The implication: While right-wing blowhards may infuriate Democrats, they sometimes pose the greatest danger to their own true believers. The bombast of people like Limbaugh and Trump in this case was lethal — but only if you believed them. Doubting them conferred some immunity.

One lesson of that 2009 outbreak is the paramount importance of relying on information from scientific experts, not from ideological soul mates. I’ve been speaking to epidemiologists and other health experts, and they emphasize that in a crisis like the present one, the government must protect its credibility and the public should rely on experts rather than partisans on either left or right.

The problem is that we are all asking questions — How bad will this get? Should I cancel my trip? — that experts can’t easily answer. But living with the wise uncertainty of scientists is preferable to the ranting certainty of demagogues.

Sadly, Trump exemplifies an ideological approach to the coronavirus (and Democrats must avoid the converse tendency to predict the worst just because Trump is in charge). From the beginning, when Trump suggested that warming weather would solve the epidemic, his aim has been to downplay the risks and talk up the stock market, whose strength is key to his argument for re-election.

“We’re going very substantially down, not up,” Trump said on Feb. 26 of the number of infections. This was completely incorrect, and he piled on more narcissism: “We have it so well under control. I mean, we really have done a very good job.”