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  • Healthline asked three infectious diseases specialists what is currently know about monkeypox transmission and what they think of the CDC’s recent recommendations.
  • The route of transmission in the current outbreak appears to be close skin-to-skin contact and close respiratory contact during sexual activity
  • People who develop monkeypox may be ill for three or more weeks.

Last week the U.S. Centers for Disease Control and Prevention (CDC) released guidance on how people can practice safer sex if they think they’ve recently been exposed to monkeypox

Monkeypox primarily spreads through close contact with infectious sores, lesions and bodily fluids. It can also spread through respiratory droplets during face-to-face contact. 

The most likely route of transmission in the current outbreak appears to be close skin-to-skin contact and close respiratory contact during sexual activity

Many cases in the recent outbreak have been traced back to sex at two raves in Spain and Belgium. The vast majority of patients include men who have sex with men.

The CDC has offered new advice to limit the risk of disease transmission during sex. These recommendations included virtual sex, masturbating together at a distance of at least 6 feet, having sex while clothed, and avoiding kissing.

We asked three infectious diseases specialists what we know about monkeypox transmission and what they think of the CDC’s recent recommendations. Here’s what they said. 

Dr. Stanley Deresinski, a clinical professor of medicine and infectious diseases at Stanford Medicine

Dr. Monica Gandhi, an infectious disease specialist with the University of California, San Francisco 

Dr. Richard A. Martinello, a Yale Medicine infectious disease expert

Healthline: How easily can monkeypox spread through sexual contact? 

Gandhi: In the current outbreak, over 3,100 cases have been reported in 58 non-endemic countries, mainly among men-who-have-sex-with-men (MSM). Although this outbreak is very concerning and relevant communities need to be aware and protected, monkeypox is likely not spreading very efficiently given the degree of sexual activity worldwide and the relatively low number of cases reported in comparison.

Martinello: While we do not consider monkeypox to be a sexually transmitted disease, the close contact and potential exposure to body fluids, including respiratory tract droplets, allows monkeypox to be spread during sexual contact.

Deresinski: It can readily be spread through skin-to-skin contact, as occurs during sex. The virus has been reported to be present in semen, but the role of semen in transmission has not been demonstrated. Body fluids, including respiratory tract droplets, allow monkeypox to be spread during sexual contact.

Healthline: It seems as though exposure to an infected person’s lesions has a greater risk compared to exposure to an infected person’s respiratory droplets. Why is this? 

Deresinski: Transmission of the virus requires close contact – there is no evidence of aerosol transmission, as occurs with, e.g., SARS-CoV-2 (although it must be remembered that the smallpox virus, a close relative of monkeypox, was transmitted by aerosol).  

In contrast to small aerosol particles, large respiratory droplets do not remain suspended in air for long and do not travel distances. Past experiences with monkeypox in the U.S. confirms its limited transmissibility.  

Gandhi: Monkeypox has never spread efficiently by respiratory droplets as evidenced by the endemic outbreaks which are usually the result of animal exposure. For example, prior to current outbreak, the last case in the U.S. was identified on July 15, 2021 in a U.S. resident who had traveled from Nigeria to the U.S. on two commercial flights. Contact tracing revealed 200 contacts and none developed symptoms indicating the rarity of human to human transmission by casual respiratory contact.

Martinello: I am not aware of any data showing that exposure to an infected person’s respiratory droplets are less risky than exposure to their lesions

Healthline: If a person’s partner is infected, how long should they follow the CDC’s safer sex tips?

Martinello: Persons who develop monkeypox may be ill for 3 or more weeks. While we typically consider persons to be no longer contagious once the lesions have all scabbed and the scabs have fallen off, it is not clear how long there remain a risk for transmission of monkeypox during sexual contact. It would be best for a recovering person to speak with their physician and the department of public health to receive the latest guidance for this question.

Deresinski: Monkeypox typically lasts 2 to 4 weeks before complete resolution.

Gandhi: Patients can develop an [early symptom] of fever and the skin lesions usually progress over 2-3 weeks from flat (macular) to raised (papular then vesicular) to looking like pus-filled blisters (pustular), before scabbing over and resolving. A person can be infectious until the lesions scab over which can take up to 3 weeks. 

Healthline: The CDC recently issued guidance on practicing safer sex to avoid monkeypox transmission. What are your thoughts on the guidance? 

Deresinski: Overall okay, except that it would be safer to more carefully select your sex partners until this outbreak is resolved. Wearing clothes during sex may well be insufficient to prevent transmission.  

Martinello: There remains much unknown about the actual mode(s) of transmission of this virus. Since there is concern for monkeypox to be spread by respiratory droplets, more precise guidance on the protection from transmission (as we see for HIV and STDs) is not possible until additional research is completed.

Gandhi: CDC guidance can often be unrealistic such as counseling Americans to not eat sushi or cookie dough.  Similarly, counseling people to have sex with “their clothes on” can be perceived as unrealistic, although both the CDC and the WHO have employed messaging on this recent monkeypox outbreak that is more akin to “harm reduction” messaging by not recommending complete abstinence

This concept of “harm reduction” in infectious diseases originates from the HIV epidemic and involves public health recommendations that both minimize the impact of a pathogen, while accounting for the needs of the individuals and communities involved.

Healthline: What led the CDC to issue this guidance?

Martinello: At least some of the current outbreak of monkeypox is due to spread associated with sexual contact. CDC highlighting this concern and advising the public on how monkeypox can be spread during sexual contact is an important public health message. 

Gandhi: As above, monkeypox was not reported to spread through sexual contact before but this large recent outbreak in non-endemic countries is mainly occurring among MSM reporting sexual activity and so the CDC is issuing appropriate guidance on avoiding sexual risk.

Deresinski: It has been known that skin-skin contact transmits the virus and direct sexual contact involves such contact. The concern about sexual contact in the current outbreak arises from the identification of skin lesions in the [anus and genital] area and the epidemiology of cases in the outbreak.

Healthline: Are there any tips you’d like to reinforce or offer an alternative suggestion to? 

Deresinski: The soundest advice from CDC: “If you or a partner has monkeypox, the best way to protect yourself and others is to not have sex of any kind (oral, anal, vaginal) and not kiss or touch each other’s bodies while you are sick, especially any rash or sores. Do not share things like towels, fetish gear, sex toys, and toothbrushes.”

Martinello: It is always a good idea to know any sexual partner well, communicate, and ensure they are free of any communicable disease prior to sexual activity in addition to using condoms to help prevent the spread of STDs, HIV and monkeypox.

Gandhi: Avoiding close physical contact with someone with active lesions which resemble monkeypox will be protective.

Healthline: Is there anything else we can be doing to reduce the risk of contracting monkeypox? 

Deresinski: There are vaccines that provide protection, although the supply of the preferred vaccine is limited. However, the U.K. has initiated vaccination of highest risk individuals.

Martinello: It is important to know that monkeypox is not a risk for most people currently — there is no need for unnecessary concern. However, now is the time to learn about monkeypox, the illness it causes and understand if you need to take any actions to decrease your risk.

Gandhi: The Jynneos vaccine is highly effective in protecting against monkeypox. Canada just signed a $56 million deal with the manufacturer of the Jynneos vaccine, and the U.S. is expanding its Jynneos vaccine supply so I would encourage our country to be proactive with vaccinating MSM and close contacts.