Health officials in Chicago have reported a new cluster of 13 mpox cases among gay men, raising concern about a possible resurgence this summer, which unofficially kicks off during the upcoming International Mr. Leather contest over Memorial Day weekend.
A majority of the men were fully vaccinated, which suggests waning protection. Nonetheless, local and national health authorities are urging people at risk to start or complete vaccination ahead of next month's Pride events.
"We want to make sure that everyone can enjoy a happy and healthy Pride," San Francisco health officer Dr. Susan Philip said in a Department of Public Health statement. "If you received your first dose of the mpox vaccine, even if it was in the fall, it is not too late — now is a great time to get your second dose."
It takes about two weeks after the second dose of the Jynneos vaccine to develop maximum immunity. People who get their first dose now will be eligible for a second dose four weeks later and should be fully protected by late June, the DPH noted.
San Mateo County Health officials also urged at-risk individuals to protect themselves against the mpox virus as Pride Month approaches. After more than six months without a case, San Mateo County health officials reported one case this month, according to a news release.
Clusters in Chicago and France
Mpox cases have declined dramatically since the outbreak peaked late last summer, likely due to a combination of behavior change, vaccination, and natural immunity after infection. In late April, the federal Centers for Disease Control and Prevention saw the first week with zero new case reports. To date, the CDC has identified 30,361 mpox cases in the United States and more than 87,000 cases worldwide, mostly among men who have sex with men and their sexual partners.
But the reprieve may not last. As of May 9, Howard Brown Health in Chicago, which serves the LGBTQ community, had diagnosed eight new mpox cases since mid-April, after diagnosing only one case during the preceding three months. Chicago health officials have identified a total of 12 confirmed cases and one probable case — the largest cluster seen in the United States this year. All were gay or bisexual men, according to the local health department.
Similarly, French health officials recently reported a cluster of 17 new mpox cases in the Centre-Val de Loire region south of Paris, mostly diagnosed after March 1. But only two new cases were reported in France in April, suggesting that this may not be the start of an ongoing outbreak.
While the overall number of mpox cases worldwide continues to decline, there are other trouble spots, according to the World Health Organization. WHO recently reported that of the 111 newly confirmed cases in Africa during the last two weeks of April, 106 were in the Democratic Republic of Congo. Japan and South Korea have also seen recent outbreaks.
Vaccine uptake and effectiveness
With the jump in new cases, health officials are reemphasizing the importance of vaccination, but it is still not certain how well the Jynneos vaccine works or how long protection lasts.
Preliminary data from the CDC shows that vaccine effectiveness is estimated to be 69% with two doses and 37% with a single dose. What's more, a recent report in The Lancet described two cases of unvaccinated men who appeared to be reinfected after recovering from mpox last summer, indicating that natural immunity may also be incomplete.
Over two-thirds of the men in the Chicago cluster and about a third of those in the French cluster were fully vaccinated with two Jynneos doses. However, all the Chicago cases were mild and no one required treatment, suggesting that the vaccine prevents severe illness even if it is not fully protective against infection.
"Since no vaccine is 100% effective, it is important for individuals to reduce their risk of potential exposures to mpox both before and after being vaccinated," SF DPH said in a statement.
Inadequate vaccine uptake is also a concern. To date, more than 1.2 million doses have been administered in the United States and over 50,000 have been given in San Francisco. Yet according to the CDC, only 23% of people at risk for mpox are fully vaccinated and 37% have received one dose.
The vaccination rate is higher in San Francisco: 42% of HIV-positive people and 65% of HIV-negative people taking PrEP have received at least one dose, DPH previously told the Bay Area Reporter. However, a DPH study presented at the recent Conference on Retroviruses and Opportunistic Infections showed that among those living with HIV, Black people, transgender women, and people experiencing homelessness are less likely to be vaccinated; no significant differences were seen among people taking PrEP.
Vaccination is especially crucial for people with advanced HIV, who are more likely to develop severe mpox illness, experts have said. In addition, starting and staying on antiretroviral treatment can reduce the risk for mpox complications.
Mpox is "very starkly different" among HIV-positive people with advanced immune suppression, Dr. Chloe Orkin of Queen Mary University of London reported at CROI. In an international cohort of nearly 400 people with HIV, no one with a CD4 count above 200 died, but mortality approached 30% for those with a count below 100. Of the 42 people known to have died with mpox in the United States, most have been Black gay men with AIDS.
Officials urge vaccination
Even if vaccine protection is incomplete for individuals, health officials stress that increasing vaccination is key to keeping mpox under control at the community level.
"The more people who get vaccinated, the better protected the LGBTQ+ community will be from another outbreak of monkeypox this year," Howard Brown Health chief medical director Dr. Patrick Gibbons stated in a news release. In particular, he urged unvaccinated people who plan to attend International Mr. Leather weekend at the end of May to get their first dose as soon as possible.
SF DPH strongly recommends two doses of the Jynneos vaccine for all people living with HIV, anyone taking or eligible to take PrEP, and "all men, trans people, and nonbinary people who have sex with men, trans people, or nonbinary people." Anyone outside those groups who wants protection against mpox may also request the vaccine.
To facilitate uptake, DPH has scheduled two vaccination events in SOMA in partnership with Folsom Street Events and the Leather & LGBTQ Cultural District. The events will take place May 13 and June 10 from noon to 5 p.m. on 12th Street between Folsom and Harrison streets.
Vaccines are also available through health systems, community clinics such as the San Francisco AIDS Foundation's Strut clinic, and SF DPH-affiliated sites, including City Clinic. (Click here for more information about vaccination sites.)
"The more people who need vaccine who get it, the better our protection from large outbreaks," White House mpox deputy coordinator Dr. Demetre Daskalakis wrote on Twitter. "For people who still get mpox after vaccination, the vaccine still works! Their symptoms may be milder and hospitalization may be less likely."
He added that people experiencing mpox symptoms — which may include flu-like symptoms and a rash or sores anywhere on the body — should get tested regardless of whether they have been vaccinated.
Mpox livestream May 12
Federal health officials will present a livestream on mpox Friday, May 12, at 8 a.m. Pacific time. Sponsored by InterPride, the session, featuring trans Assistant Secretary for U.S. Department of Health and Human Services Admiral Rachel Levine and gay White House National Mpox Response Deputy Coordinator Dr. Demetre C. Daskalakis, will focus on prevention and vaccination. It can be viewed here.
Updated, 5/11/23: This article has been updated with information about a livestream on mpox.
Updated, 5/17/23: This article has been updated with information from San Mateo County.
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