by Robin Foster

Mpox cases are climbing again in the United States, with the number of reported infections now twice as high as they were at this time last year, new government data shows.

In response, public health experts have raised alarms about the increase and stressed that vaccination rates against the disease need to improve.

"This has the potential to become a fairly prevalent infectious disease, but the advantage with mpox is we have a vaccine that's effective. We don't have that for syphilis, gonorrhea, chlamydia or HIV," Dr. Marcus Plescia, chief medical officer for the Association of State and Territorial Health Officials, told CNN.

"We've had fairly good participation in the vaccination push, but we're not anywhere close to getting most of the at-risk population vaccinated. Until that happens, we're going to see outbreaks and upticks in cases in various places."

Through March 16, there have been 511 mpox cases reported, according to data from the U.S. Centers for Disease Control and Prevention. By late March 2023, there were fewer than 300 cases reported.

Transmission rates are still far below levels from 2022, when an mpox outbreak fueled tens of thousands of cases in the United States. But the public health emergency expired more than a year ago, cutting the amount of federal resources available to manage a public health response, CNN reported.

On top of that, the CDC sent a health alert out in December warning of another subtype of the virus that has been found to be more transmissible and to cause more severe disease than the subtype associated with the 2022 outbreak. This particular version of the virus hasn't yet emerged in the United States, but it is spreading in the Democratic Republic of Congo, CNN reported.

Mpox, formerly known as monkeypox, is spread through close personal contact. Initial symptoms include fever, chills, exhaustion, headache and muscle weakness, often followed by a rash with lesions that scab over and slowly heal over a period of weeks.

Although anyone can get mpox, men who have sex with men are particularly at risk, and those who have HIV are more vulnerable to severe disease. The mpox vaccine, manufactured under the brand name Jynneos, is a two-dose regimen, with the shots given about a month apart.

But in most states, less than a quarter of the population at risk has been fully vaccinated with the two-dose series since it was authorized for emergency use in August 2022, CDC data shows.

Meanwhile, nearly all U.S. regions have reported more cases this year than in the first three months of 2023, with the largest difference in the mid-Atlantic region, according to the CDC.

On Monday, the Virginia health department sent out a notice to raise awareness about the recent rise in cases.

The state has had as many cases this year as there were in all of 2023. Among the 12 reported cases, four required hospitalization, six also had HIV and none had been vaccinated, the notice said.

"We felt like it was really important to get the word out that there is a continued risk from this virus. It's still here," Dr. Brandy Darby, director of the Division of Surveillance and Investigation in the Office of Epidemiology at the Virginia Department of Health, told CNN.

"We also wanted to give people time to protect themselves ahead of Pride season. We're hoping this might encourage people to go ahead and get vaccinated so they can go out and enjoy their celebrations and not have to worry so much about mpox."

The alert might make a difference: An August survey found that about half of men who have sex with men changed their behaviors because of the 2022 mpox outbreak. Research has found that these changes helped curb the spread of mpox, but experts noted vaccination is a more realistic prevention tool.

The U.S. government managed the supply of mpox vaccines during the 2022 outbreak, but that process has since been commercialized. The government does have some vaccine supply remaining, and the shots are expected to be available in pharmacies and health care offices next month, experts told CNN.

More information: Visit the U.S. Centers for Disease Control and Prevention for more on mpox.

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