Mpox is caused by a virus that can be spread through touching the affected skin of someone who has the infection, touching sheets or clothes that has been used by someone with the infection, or breathing in particles of virus from someone who has the infection. Mpox infection can cause skin and flu-like symptoms, but can also cause very few symptoms, or no symptoms at all. While the number of participants with mpox symptoms can be tracked, little is known about how many people have mpox, but experience few or no symptoms at all. To do this, a Canadian sample of gay, bisexual and other men who have sex with men (GBMSM) who are participating in a randomized controlled trial will be screened for mpox symptoms. Screening will include questions about whether they may be experiencing any mpox symptoms, history of past diagnosis of mpox, sexual history, and vaccination history and awareness. Swabs will be taken to test for the presence of mpox virus, and a blood sample will be taken to test for antibodies. Approximately 450 individuals will be recruited. The results will be descriptive in nature.