Mpox cases in the US are on the rise as vaccination rates lag and new threats loom

Mpox cases in the United States are twice as high as they were at this time last year, and experts are stressing the importance of improving vaccination coverage as transmission risks rise.

Mpox cases in the United States are twice as high as they were at this time last year, and experts are stressing the importance of improving vaccination coverage as transmission risks rise. There have been 511 cases reported this year through March 16, according to data from the US Centers for Disease Control and Prevention — compared with fewer than 300 cases by late March 2023. Transmission rates are still far below levels from 2022, when there were tens of thousands of cases in the US. But after a quieter year last year, experts say the US is vulnerable to increases in spread in a number of ways. The public health emergency in the US expired more than a year ago, cutting the amount of federal resources available to manage the public health response. And relatively low vaccination rates leave many at risk. In December, the CDC also sent a health alert warning health-care providers about another subtype of the virus that has been found to be more transmissible and cause more severe disease than the subtype associated with the 2022 outbreak in the US. This particular genetic clade has not been identified in the US, but it is spreading in the Democratic Republic of Congo. “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,” said Dr. Marcus Plescia, chief medical officer for the Association of State and Territorial Health Officials. “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.” Mpox, formerly known as monkeypox, is a less severe cousin of the now-eradicated smallpox virus, and it is spread through close personal contact. Initial symptoms are typically flu-like — including fever, chills, exhaustion, headache and muscle weakness — often followed by a rash with raised lesions that scab over and resolve over a period of weeks.