Recent STI plunge may be due to mpox aftermath, experts say

  • by John Ferrannini, Assistant Editor
  • Friday June 30, 2023
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San Francisco health officials are cautiously optimistic about lower rates of sexually transmitted infections, and continue to encourage people at risk of mpox to get vaccinated. Photo: Gooch
San Francisco health officials are cautiously optimistic about lower rates of sexually transmitted infections, and continue to encourage people at risk of mpox to get vaccinated. Photo: Gooch

The three most common sexually transmitted bacterial infections are down, according to public health data — and not just in San Francisco, but nationwide, too.

It's unclear why, but behavioral changes after the mpox outbreak affected gay and bi men last summer could be part of the answer for the decline in gonorrhea, chlamydia, and syphilis, according to public health experts.

Over 50,000 doses of the mpox vaccine were distributed last year in San Francisco, the Department of Public Health stated, covering 42% of all people living with HIV in the city and 65% of people who had received PrEP at San Francisco City Clinic prior to June 2022.

PrEP, or pre-exposure prophylaxis, is a drug to prevent HIV infection. Mpox, though not an STI per se, is spread by close bodily contact, and most reported cases since last year were among sexually active men who have sex with men and their sexual partners. Since last year, 846 San Franciscans have had mpox, according to health department data.

The latest San Francisco Monthly STI report for April shows there'd been 1,584 cases of gonorrhea reported in the city in 2023 as of the end of that month, compared to 1,882 as of that time last year. Of gonorrhea cases so far in 2023, 545 were male rectal gonorrhea, compared to 749 last year during the same period.

There were 2,024 cases of chlamydia — the most common STI — reported in San Francisco as of the end of April compared to 2,183 at that time last year. Of chlamydia cases in 2023, 655 were male rectal chlamydia, compared to 680 last year.

There were 483 cases of syphilis reported in San Francisco as of April 30, compared to 612 last year during the same period, the report stated.

The city introduced the use of doxycycline as post-exposure prophylaxis for chlamydia and gonorrhea last year, referred to as doxy-PEP, as the Bay Area Reporter previously reported. Still, according to Jorge Roman, a gay man who is the senior director of clinical operations at the San Francisco AIDS Foundation, it's too early to know how much of an effect that's had.

"Doxy-PEP wasn't really started until October," he said. "City Clinic was the first in the beginning of November. We got involved in the third week, but we were seeing declines before that. We are really optimistic we will be seeing effects with a larger uptake of doxy-PEP."

Indeed if the city's monthly STI reports are any indication, unprotected sex cooled down last summer among gay and bisexual men. For example, there were 170 male rectal gonorrhea cases in July, 144 in August, 135 in September, and 124 in October.

In April, there were 110 cases, according to the report.

Nationally, according to the Centers for Disease Control and Prevention, cases as of June 17 of the three big three bacterial STIs were all down from 2022 levels: 78,451 fewer gonorrhea cases, 102,461 fewer chlamydia cases, and 9,218 fewer syphilis cases were reported in the United States, compared to 2022 numbers.

Dr. Stephanie Cohen, a straight ally who is the section director for HIV/STI prevention with the San Francisco health department, agrees with Roman.

"I think it's too early to really start attributing the trends to doxy-PEP," Cohen said. "We do know the uptake has been high among men who have sex with men and trans people in San Francisco, but I think we need more time to monitor among different populations before attributing what we're seeing to doxy-PEP itself."

Roman said that he expects doxy-PEP to lead to further reductions in STI rates. He said anecdotally the AIDS foundation's Magnet clinic at SFAF's Strut health center in the LGBTQ Castro neighborhood is seeing declines in STI rates.

"I couldn't give hard data yet — we're just delving into our doxy-PEP information right now, and we're hoping to put that out in the coming weeks," he said. "But anecdotally, yes, we are seeing changes for the better."

Still, people should be informed, Cohen said. The city has seen four mpox cases this year, with the most recent being in May. That said, Los Angeles public health officials reported six new cases in a week after Pride festivities in L.A. and the gay enclave of West Hollywood in the first two weeks of June.

"We really strongly encourage people at risk for mpox to get the full series of vaccine," Cohen said. "It's an important example of biomedical prevention."

Two doses of the Jynneos vaccine, given about a month apart, provide the best protection against mpox, health officials said.

For information on the mpox vaccine, click here.

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