CDC Expects US Monkeypox Cases to Decline or Plateau Over Next 4 Weeks

This 2003 electron microscope image made available by the Centers for Disease Control and Prevention shows mature, oval-shaped monkeypox virions (L) and spherical immature virions (R) obtained from a sample of human skin associated with the 2003 prairie dog outbreak. Cynthia S. Goldsmith, Russell Regner/CDC via AP

The U.S. Centers for Disease Control and Prevention (CDC) said Friday it has “moderate confidence” that daily monkeypox cases in the United States will plateau or decline in the coming weeks but an increase is possible.

In its third technical report on the monkeypox outbreak, the CDC said cases likely peaked in August and that going forward, the outbreak could plateau, decline, or exponentially rise slowly or rapidly.

“Among these scenarios, we assess daily cases in the United States will most likely continue to decline or plateau over the next two to four weeks. We have moderate confidence in this assessment but note the possibility, as described above, that incidence could increase again,” the technical report states.

Since the first U.S. case in Massachusetts in May, there have been 24,841 monkeypox cases reported to the CDC. The median age of cases is 34. As far as the CDC is aware, there have been 29 confirmed and around 50 probable pediatric cases, which are defined as people younger than 18.

The agency noted that data is voluntarily reported to the agency and that of the total cases to date, 84 percent included age data.

Since August, monkeypox cases have trended down, averaging 144 per day on a rolling average. However, the CDC noted that cases are not declining across all jurisdictions.

The CDC noted in its report that there is still a “large uncertainty” around the long-term trajectory of the outbreak owing to not knowing what “behavior change” may or may not occur within the sexual networks of the LGBT community.

Outbreak Update

Around half of the monkeypox cases reported male-to-male sexual activity in the three weeks preceding symptom onset. Men who have sex with men have been the primary vector of transmission of the virus in the 2022 outbreak.

The decrease in case number has largely been attributed by health officials to a change in behavior among men who have sex with men.

The CDC noted that while its first two technical reports included data on sexual orientation, going forward this data won’t be nationally reported and is not included in the latest report.

The report did not say why, but throughout the outbreak health officials and LGBT advocates have cautioned against and expressed concern about stigmatizing the gay and bisexual community.

While vaccines have been available, the CDC noted that they weren’t likely the primary factor for the drop in cases because jab rates were still low at the time. Demand has consistently outpaced supply for monkeypox vaccine amid the outbreak.

The virus is “unlikely” to be eliminated in the United States, but the CDC expressed some confidence that cases won’t go up.

“While unlikely, elimination could occur if monkeypox is and remains concentrated in a high-risk subset of MSM, and vaccination efforts are focused on this exposure group and are effective in preventing infection, both factors which would cause faster declines in transmission,” the technical report states, referring to men who have sex with men as ”MSM.”

“However, we view this scenario as unlikely due to the possibility of continued introductions and onward transmission.”

The CDC only had data about symptoms for less than half of the total cases. But in the data the agency does have, nearly all cases reported rashes and a majority had a fever, malaise, chills, pruritus, headache, lymphadenopathy, and myalgia.

Half of the cases the agency has data for also reported rectal pain.

The majority of the cases by race are around 34 percent black, 29 percent white, 29 percent Hispanic, 3 percent Asian, and 1 percent reported as other. Less than 1 percent reported as native American, native Hawaiian, or Pacific Islander.