Q: I get cold sores several times a year. Is there a way to keep them from coming back?

It usually starts with a tingling at the edge of your lip. Painful, fluid-filled bumps emerge. Then they pop, ooze, scab over and eventually heal. Every few months, this cycle repeats.

Cold sores, also known as fever blisters, can develop after infection with the herpes virus. (They’re commonly caused by a version of the virus called herpes simplex virus type 1, or HSV-1, which is different from the version that typically causes genital herpes.)

But Mr. Westwood and his colleagues found the opposite. In the weeks after the attack, Americans’ support for partisan violence, and murder specifically, diminished — and fell most sharply among Republicans who identify with Mr. Trump.

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For many, the lesions are “unsightly and painful,66jogo” said Dr. Christine Johnston, a professor of infectious diseases at the University of Washington School of Medicine. They’re also common, she added: Roughly half of people in the United States have HSV-1.

Here’s how to treat cold sores, and whether you can prevent them.

What causes cold sores?

The herpes virus is “very contagious,” said Dr. Dean Blumberg, chief of pediatric infectious diseases at UC Davis Health. You can pick it up through close contact with someone who is infected, such as through kissing or sharing food or drinks.

And it’s not always easy to tell whether someone is contagious, Dr. Blumberg said. People can transmit oral herpes without a visible cold sore.

If you do become infected, you might not develop a cold sore right away or even at all, Dr. Blumberg added. It could take years before you have an outbreak, Dr. Johnston said, or maybe you never get one.

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