As cases of monkeypox continue to mount in the United States and abroad, infectious disease experts are closely monitoring one group of people in particular: women.
So far, the overwhelming majority of cases of the viral disease have been reported in men who have sex with men. But in recent days, officials have learned of a handful of cases in women – possibly indicating that the outbreak may be widening.
Researchers are keeping close tabs on the proportion of cases in women to “assess whether the outbreak is moving away” from networks of men who have sex with men, where most of the initial cases have been identified, according to a briefing from the UK Health Security Agency (UKHSA).
“There is insufficient evidence to support a change in the transmission dynamics,” the agency said. “However, over the last few weeks the proportion of female cases has been increasing, so this trend needs to be monitored closely.”
A global collaboration of researchers and clinicians recently described 528 cases of monkeypox in 16 countries – but none were in women.
Since data collection for that study ended in June, the research group has confirmed cases in women, said study coauthor John P. Thornhill, MD, PhD, consultant physician in sexual health and HIV and clinical senior lecturer at Barts Health NHS Trust and Queen Mary University of London.
“Cases in women have certainly been reported but are currently far less common,” Dr. Thornhill told this news organization.
Although infections in women have been outliers during the current outbreak, they can be severe when they do occur. Several women in England have been hospitalized with severe symptoms.
A similar pattern has been seen in New York City, where just one woman is among the 639 total cases, according to a July 21 report from the city’s health agency.
Researchers have recently published guidance on monkeypox for ob.gyns., maternal-fetal medicine subspecialists, and people who are pregnant or breastfeeding in anticipation of the possibility of more cases in women.
The Centers for Disease Control and Prevention advises that “pregnant, recently pregnant, and breastfeeding people should be prioritized for medical treatment” of monkeypox if needed.
One monkeypox vaccine, Jynneos, can be offered to people who are pregnant or breastfeeding and are otherwise eligible for vaccination on the basis of confirmed or likely contact with cases, ideally within 4 days of exposure. Some people at high risk for exposure, such as laboratory workers, may receive the vaccine preemptively.
Another vaccine, ACAM2000, is contraindicated in people who are pregnant or breastfeeding, according to the CDC.
Investigators have not yet identified substantial spread of monkeypox beyond men who have sex with men, although transmission among household contacts, including women and children, has been reported.
Most initial infections during the current outbreak occurred during sexual activity. But monkeypox can spread through any close contact with skin lesions or body fluids and possibly through touching contaminated items like clothing or linens, according to the CDC. It also may spread from mother to child in utero.
Infected pets have been known to spread the disease as well. A multistate monkeypox outbreak in the United States in 2003 was linked to pet prairie dogs, including in childcare and school settings. That year, 55% of the 71 cases occurred in female patients.