Immune system fights infection

Vaccines are on everyone’s mind lately — since they offer hope that COVID-19 can be contained, even defeated. But we’re hearing that most folks don’t understand how they work or what can be expected from them. So here’s our 101 on the immune system and vaccination.

The body’s multilayered defense against infection works like this: Bacteria and viruses can be stopped by the quick response of your innate immune system when the microbes come into contact with your skin or your nasal and intestinal layers. Inflammatory cells and soluble proteins get activated. Blood circulation increases and an affected area can become swollen and hot. Sometimes you get a fever.

If that doesn’t eliminate the invader, then scavenger cells or phagocytes get into the act in the body’s tissue and blood, gobbling up the pathogens. Hungry macrophages (a kind of white blood cell) react to the antigens (parts of the invading germs). Natural killer cells then get into the act, identifying cells in your body that are infected, so that those killer cells, along with white blood cells that produce antibodies, can be activated.

The adaptive immune system launches a more targeted reaction using the immune system’s T and B cells, which can spot specific invaders in tissue and fluids, but it can take several days (or more) for there to be a robust response.

Vaccines are designed to stimulate your body’s built-in defenses to infection by introducing an altered version of the infecting agent — one that makes your immune system mistakenly think you are being attacked by a fully active virus when you are not. This revs up your killer T cells and your antibody-producing B cells, stopping a virus before it makes you sick.

So, watch for the launch of various COVID-19 vaccines. We will write about the vaccine when we judge it’s safe enough to get ourselves — and we hope you’ll get yours then, too.

Mehmet Oz, M.D. is host of “The Dr. Oz Show,” and Mike Roizen, M.D. is Chief Wellness Officer and Chair of Wellness Institute at Cleveland Clinic. To live your healthiest, tune into “The Dr. Oz Show” or visit www.sharecare. com.