How to Keep Your Immune System in Fighting Shape When Cold Season Is in Full Force

We’ll spare you the lecture about how you should’ve gotten one in November, but if you still haven’t, it’s not too late. Yes, effectiveness varies year to year, but it can reduce your risk by up to 60 percent—and there’s no downside. (OK, maybe a teensy bit of pain.)

Yes, that means your hands—remember to scrub for 20 seconds or as long as it takes to sing the “Happy Birthday” song twice—but also your desk, your keyboard, your iPhone… It might feel like overkill to bust out the Lysol daily, but you’d be surprised (and grossed out) at the number of germs that live on commonly used surfaces (including money—ew).

Raise your hand if you’ve ever thought, I’ll kill whatever germs are in me with alcohol! Sadly, that logic doesn’t work inside your body: Too much booze actually inhibits white blood cells’ ability to destroy bacteria. A drink here or there shouldn’t be a problem, but maybe hold off on Wine Wednesdays until everyone’s feeling 100 percent.

We know; it’s tragic. But that chocolate-chip cookie isn’t doing you any favors. Not only because it’s taking the place of more vitamin-rich food, but because it suppresses your immune system in the same way that alcohol does.

With Pinot Grigio and doughnuts off the table, what can you eat? Easy: nutrient-rich foods like oats (which have antimicrobial properties), shellfish (which helps regulate immune response), garlic (a natural infection-fighter) and green tea (high in antioxidants). Oh, and your mom’s insistence on chicken soup? It’s actually valid: The specific amino acids in chicken broth are especially good at fending off respiratory trouble.

Not all bacteria is bad: The healthy strains that live in your digestive system can actually keep the bad stuff from getting in. Keep those levels optimal by taking a supplement and eating yogurt (unsweetened, of course), apple cider vinegar and fermented foods like kimchi.

Your New Yorker definition of “enough” might be five and a half hours, but your body doesn’t know that. Sleep deprivation can reduce antibodies and increase inflammation—in other words, your susceptibility to illness skyrockets. Aim for at least seven uninterrupted hours. (And if you’re prone to insomnia, try these secret weapons.)

No, you don’t have to wear one of those surgical masks, but every minute you’re stuck on a packed Q train, you’re breathing any airborne germs your fellow commuters might have brought in (yuck.) Pull your scarf over your nose and mouth, and if you hear someone sneeze, hold your breath for 15 to 20 seconds (that “Happy Birthday” trick works here, too).