In May, an outbreak of monkeypox began in Europe and North America. While it has so far primarily affected gay and bisexual men, anyone can get monkeypox through close personal contact.

The monkeypox virus is transmitted from animals and from person to person via close contact. This can include skin-to-skin contact, kissing and contact with contaminated clothing, bed linens or surfaces. It also can be transmitted through respiratory droplets at close range, but it doesn’t spread through the air over longer distances, like the coronavirus that causes COVID-19. It is not yet known whether monkeypox is directly sexually transmitted through semen or vaginal fluid, but it does spread via contact with sores during sex.

Monkeypox has an incubation period of up to three weeks, and the illness usually lasts two to four weeks. It typically causes flu-like symptoms, swollen lymph nodes and a rash. The sores can appear on the face, in the mouth or elsewhere on the body. In the current outbreak, many men have presented with lesions on the genitals or in the anal area. The sores often start out as flat red spots and progress to firm, raised lesions that fill with clear fluid and then pus. The rash may resemble chickenpox or common sexually transmitted infections, such as herpes or syphilis.

To reduce the risk of monkeypox transmission, avoid sexual contact and social gatherings, seek medical care if you feel ill or have a rash and ask sex partners about their health too. Avoid sharing sex toys or personal items like toothbrushes. Wear long sleeves and pants at crowded gatherings to minimize skin-to-skin contact. Although it is unclear whether condoms can prevent transmission via semen, some health agencies recommend them as a precaution.

People who test positive for monkeypox should isolate for three weeks. Those who think they might have been exposed should self-monitor for symptoms. Wearing a mask can help protect household members and caregivers during face-to-face contact. Cover sores with clothing or bandages. Monkeypox remains infectious until the sores heal completely and scabs fall off.

Smallpox vaccination can prevent monkeypox as well. In the United States, people around age 50 or older who were previously vaccinated may still have some protection, but immunity could have waned over time.

A new, safer nonreplicating smallpox and monkeypox vaccine (Jynneos or Imvanex) was approved in 2019. An older live virus vaccine (ACAM2000) can cause adverse side effects, especially for immunocompromised people and people with skin conditions.

Monkeypox can be contained through targeted vaccination of close contacts of an infected person. Because the virus has a long incubation period, vaccines may be used as post-exposure prophylaxis within several days after exposure. But contact tracing can be difficult or incomplete, so the Jynneos vaccine is also given as pre-exposure prophylaxis for people at high risk, such as gay and bi men with multiple sex partners.

Most people with monkeypox recover without treatment, and there have been no deaths in the current outbreak. But the sores can leave scars, and people with more severe disease may develop complications, including bacterial infections, pneumonia and vision loss. Some anti-viral medications used to treat smallpox can also be used for monkeypox.

Severe outcomes are more likely among children, pregnant people and immunocompromised individuals. People on antiretroviral therapy with well-controlled HIV do not appear to be at greater risk, but those with unsuppressed HIV and a low CD4 count may have worse outcomes.

Viruses don’t discriminate based on identity—anyone can get monkeypox—but some types of behavior do help them spread. When considering sex or other close contact, be aware of your health and seek care if you have a rash or other symptoms.