CDC warns about mpox resurgence this summer, urges vaccination

The Centers for Disease Control and Prevention (CDC) is raising the alarm about a “substantial risk” of a resurgence of mpox cases this summer and is urging gay, bisexual and other high risk individuals to get fully vaccinated.

Officials said Thursday they are investigating a new cluster of cases detected in Chicago earlier this month, one of the first major outbreaks since cases dropped off precipitously last fall.

All of the cases were among men between the ages of 24 and 46, and they all exhibited mild symptoms, said Demetre Daskalakis, deputy head of the White House mpox task force.

Yet many of the 21 cases found in Chicago were among people who were either partially or fully vaccinated, raising questions about the durability of the shot’s immunity and whether it wanes over time.

But Daskalakis noted that even if the shot doesn’t completely prevent infection, people who have received two doses have a much lower risk of catching and spreading the disease.

“Simply put, higher vaccination rates equal lower risk for an outbreak,” Daskalakis told reporters. “So even though no vaccine is perfect, even imperfect immunity in many people, still means a lot of immunity in the population.”

Three different studies were published Thursday showing the vaccine was effective at preventing disease and reduced the severity of disease for those infected. While the methodology varied, Daskalakis said two doses are much better than one.

“It is important to say that without renewed prevention efforts, especially vaccination, we are definitely at risk of a resurgence, in fact a substantial risk of resurgence,” Daskalakis said.

More than 30,000 mpox cases and 42 deaths have been reported in the U.S. since May 2022 when the outbreak began, though cases have declined dramatically since the peak last August.

The outbreak was primarily concentrated in men who have sex with men, a group that included people who identify as gay, bisexual, transgender and nonbinary.

While more than 1.2 million people have received at least one dose of the Jynneos mpox vaccine, less than a quarter of the 1.7 million people at highest risk have been fully vaccinated with two doses, said Christopher Braden, the CDC’s mpox response incident manager.

These individuals are primarily gay and bisexual men living with HIV or who are taking drugs to prevent HIV infection, called pre-exposure prophylaxis.

The three studies released Thursday showed varying rates of effectiveness, but all indicated that two doses of the vaccine were between 66 percent and 88.5 percent effective.

“Now is the time to get vaccinated,” Daskalakis told reporters. “If you didn’t get your first dose — get it. If you didn’t get your second dose — get that.”