I’m kind of glad “Contagion” loses dramatic momentum near the end, because if the last half hour had been as terrifying as the first half hour, I would have driven my car out of the theater parking lot and through the window of the nearest CVS to loot its Purell supply. Seriously, though, through the first 30 to 45 minutes of the paranoid thriller, I kept thinking about the farmhouse we looked at today and are thinking about renting, and made plans to stockpile hand sanitizer, tuna fish and ammo in the basement.

Anyone familiar with the work of the public health journalist Laurie Garrett will know how accurate the movie’s scenario is. A new virus somehow jumps out of the animal kingdom into humans (you find out at the very end how it happened), and spreads like wildfire around the world. It kills tens of millions of people in a relatively short period of time. Civil society breaks down as the system cannot handle all the sickness and death. For all that, “Contagion” doesn’t have the grandeur of a typical Hollywood film, which I kind of appreciated — though as I said, the hair-trigger tautness of its first half hour doesn’t last.

Still, as Garrett’s readers know, the drama in “Contagion” is bound to play out in real life sooner or later. When Garrett came to the editorial board of the Dallas Morning News a few years ago to brief us on her work, she compelled me to consider for the first time how difficult it would be to maintain public order and even an economy in a situation of lethal pandemic. Indeed, the friend with whom I saw the film tonight mentioned afterwards how a buddy of his who works in public health at a top US university told him that keeping the power plants running is what worries him most about a crisis like this. In 2005, Nature, the world’s leading science journal, published a fictional account of a global flu pandemic, in an effort to dramatize what scientists believe is inevitable. It’s well worth reading.

After the movie, my friend C. and I talked on the drive home about how we would respond if it happened here. It’s hard to figure that out in advance, but a movie like this forces you to go through the exercise in imagination, especially moral imagination. One thing that emerged from our conversation: while C. and I have the luxury (or the burden) of trying to sort out how we would respond, weighing our obligations to our families against our obligations to our neighbors, there is a class of people who have no moral choice in the matter: doctors, EMTs, and first responders. The firefighters on 9/11 who rushed into the burning towers, all of them had families too, yet in they went to help others.