Charlottesville, Va.

IN early fall, a few weeks after the start of school, cold viruses wing their way from one young nose to another and thence to families and the workplace, infecting people at three to four times the rate at other times of year. And so the cold season begins and, with it, the relentless sneezing, coughing and sniffling that continue well into winter.

Most of us come down with at least a couple of colds a year; children get up to a dozen. But we all know people who seem never to catch one. What’s their secret? Do they have extraordinarily robust immune systems, and the rest of us, pathetically weak ones? You might think this was key, given the number of nutritional supplements, cold remedies and fortified cereals on the market that purport to augment the immune system  often with the help of vitamins, zinc or ginseng  and by so doing stave off colds.

But science and experience don’t back this up. On the contrary, if you’re keen on tamping down your own cold, “boosting” your immunity may be the last thing you want to do.

To understand why this is so requires a bit of knowledge about how colds work. There are more than 200 cold viruses, the most common of which are rhinoviruses (from the Greek “rin-,” for “nose”). When you encounter a particular strain, your body eventually produces antibodies to it, which remain on hand to quash that virus the next time you’re exposed. But with so many flavors of cold virus circulating, there’s always a new one to catch.