TUESDAY, May 9, 2023 (HealthDay News) -- While the mpox outbreak has been waning since last summer, it hasn't disappeared yet.

Howard Brown Health, a LGBTQ-focused health clinic in Chicago, recently reported seeing an increase in mpox (formerly known as monkeypox) cases, with eight diagnosed since April 17, compared to only one in the previous three months.

Last week’s case count was the highest in Chicago since early November 2022 and the highest weekly new case rate in any U.S. region so far this year, the clinic added. Even more troubling is the fact that six of the eight affected patients were fully vaccinated. All of the cases were mild.

“We urge sexually active members of our community to receive the mpox vaccine. For example, unvaccinated people planning to attend International Mr. Leather at the end of May should receive their first dose of the mpox vaccination as soon as possible,” Dr. Patrick Gibbons, chief medical director at Howard Brown Health, said in a clinic news release. “The more people who get vaccinated, the better protected the LGBTQ+ community will be from another outbreak of monkeypox this year.”

U.S. federal officials agreed.

“Without renewed vaccination and prevention efforts, we are at risk for a resurgence of mpox,” Dr. Demetre Daskalakis, deputy coordinator of the White House national mpox response, told NBC News. “Vaccine is a really important tool, even if it’s not perfect.”

People at high risk of mpox should get the Jynneos vaccine, Dr. Leanna Gordon, medical director of preventive medicine at Howard Brown, told NBC News.

“One of our major concerns is that our population at risk are undervaccinated,” Gordon said. “We haven’t had as much interest in the vaccine as we would like.”

Chicago isn’t the only place experiencing an uptick in mpox infections. Cases have also been increasing slightly in eight countries in the past three weeks, Rosamund Lewis, technical lead for mpox at the World Health Organization, told NBC News.

These included several East Asian countries and France, where about half of the cases were in vaccinated people, NBC News reported.

French national health authorities have said that their country has had 19 cases this year through April 3 in the Centre-Val de Loire region, 16 of them since March 1. All but one were in gay or bisexual men, NBC News reported. Ten of the people infected were fully vaccinated with either the Jynneos vaccine or a childhood smallpox vaccine followed by a recent Jynneos dose.

Since mid-April, about 21 of the 111 countries where there have been mpox cases during the outbreak have reported new cases, Lewis said.

It’s not clear how long immunity lasts after vaccination. Also not known is whether those who reduced numbers of sexual partners during the outbreak have resumed sexual practices during this time of waning cases, NBC News reported.

“Everybody’s efforts have contributed to controlling the outbreak, but it’s not gone,” Lewis said.

The virus incubates for about three to 17 days, with symptoms that include a rash and lesions. Other symptoms can include fever, chills, swollen lymph nodes, exhaustion, muscle aches, headache and sore throat.

Yet, full vaccination does reduce the risk of mpox by 69%, according to the CDC.

More than 1.2 million doses have been given to 725,000 people in the United States. About 90% of those receiving doses have been male. But only about 25% of those most at risk are fully vaccinated, the CDC says.

Daskalakis said the Chicago cases are “a call to action as opposed to a call to panic.”

“We have the tools to take care of this,” he said. “We just have to get it done.”

More information

The World Health Organization has more on mpox.

SOURCES: NBC News; Howard Brown Health, news release, May 5, 2023