The usual daily influx of around 50 patients has all but dried up, say staff. Antiretroviral drugs pile up unused.
Andrew Tendo, resident medical officer at the US-funded clinic, warned that new waves of HIV infections were forming even as vulnerable people stayed away from treatment centres, afraid of being identified and arrested under the new laws.
"The LGBT community in Uganda is on lockdown now," he said. "They don't have preventive services. They cannot access condoms ... they cannot access ARTs (antiretrovirals)."
Under the bill, which President Yoweri Museveni signed into law last week, gay sex is punishable by life in prison while "aggravated homosexuality" - which includes transmitting HIV - is punishable by death.
Until this year, the Kampala clinic had been a beacon of success for the fight against HIV in Uganda, where 1.4 million people live with the virus and 17,000 die a year as a result of its ravages, according to the state-run Uganda Aids Commission.
Now, though, when patients do come in, it's often out of absolute necessity, said Tendo, adding that the HIV cases presenting had become more severe as people skipped treatments.
Uganda's health minister disputed a suggestion from a US official that the law would reverse the country's gains fighting HIV/Aids, saying last week that the government would ensure that prevention programmes would remain accessible to those that needed them.
The health ministry declined to comment for this article.
Nonetheless, the trend of HIV patients staying away from treatment centres is being mirrored on a national level, according to Mary Borgman, country director for the US president's emergency plan for Aids Relief (Pepfar), which funds the Kampala clinic and about 80 other drop-in centres across Uganda.
She said fear had increasingly been deterring people from coming in for treatment ever since the anti-gay bill was introduced in parliament in March.
A rare patient visiting the Kampala clinic said he despaired at the new legislation.
"I felt so sad when the law was enacted because we fear Pepfar will cut off funding for the free services we have been receiving," said the 27-year-old gay man, who asked not to be identified for fear of being targeted by authorities.
"Members of the LGBT community are afraid to leave their homes, which means even if the funds are not cut some will still not seek services, and that's very depressing to think about."
Such fears of reduced American funding aren't far-fetched; after Museveni signed the bill into law, US President Joe Biden directed his national security council to evaluate the implications for US engagement with Uganda, including Pepfar.
In the 2021/2022 fiscal year, Pepfar provided $418.4m in funding to Uganda, more than half of the country's HIV/Aids treatment budget.
The programme has been instrumental in Uganda's progress against HIV/Aids, which includes a nearly tenfold reduction in mother-to-child HIV transmission over the past two decades.
Pepfar estimates its support for the scale-up of antiretroviral treatments in Uganda helped avert nearly 600,000 HIV-related deaths between 2004 and 2022.
Borgman said the American government was acutely aware of the impact any funding cuts would have on vulnerable communities, including LGBTQ Ugandans.
"The review is around whether we can operate within the environment that we are provided with," Borgman said, without elaborating on specific legal concerns.
Lillian Mworeko, the east African regional co-ordinator for the International Community of Women living with HIV/Aids, said some providers feared that offering medical services to LGBTQ patients could be classed as "promoting" homosexuality, an offence punishable by 20 years in prison under the new law.
The Ugandan bill toughened up an existing British colonial-era law, under which gay sex was already illegal. Proponents say the new legislation is needed to counter what they allege are efforts by LGBTQ Ugandans to recruit children into homosexuality.
The amended version signed by Museveni didn't criminalise merely identifying as LGBTQ - as a previous version did - and revised a measure that required people to report gay activity to only oblige reporting when a child was involved.
At the Kampala clinic, run by local charity Icebreakers, Uganda, medical officer Tendo said he understood the fears of LGBTQ people in Uganda who often endured painful lives, featuring rejection by their families and arrests.
"The majority of these people, like transgender or queer people, have gone through a lot already," he added. "They wouldn't want to be in a place where they can be raided or detained at any time."
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