(CNN) New findings presented last week at the 22nd International AIDS Conference reveal how President Donald Trump's expansion of the so-called global gag rule -- which restricts US health assistance funding to non-US NGOs that offer abortion services -- is likely to have widescale negative effects on the fight against the HIV/AIDS epidemic .

Four hundred seventy non-US NGOs working in the prevention and treatment of HIV/AIDS across the world might be subject to the expanded global gag rule, according to new data presented at the conference. These organizations received $900 million from fiscal year 2013 to fiscal year 2015.

In a few countries where the effects of Trump's expanded policy have been studied -- including Mozambique and Malawi -- women and girls are already losing access to the reproductive and family planning services they have relied on, according to panelists at the conference.

"I definitely think [the Trump policy] is the most retrograde thing that could have happened to the AIDS crisis," Robin Gorna, former executive director of International AIDS Society and current co-leader of the SheDecides support unit, told CNN.

"Because of the scale of the impact of what Trump has instituted, it's very hard to see how we can get to a position to where the services that are required can be adequately funded," said Gorna.

The Mexico City Policy, aka the gag rule

The Mexico City Policy -- often referred to as the "global gag rule" -- was instituted by president Ronald Reagan in 1984. It restricted NGOs that provided abortion-related services from receiving US funding for family planning services. The policy derives its name from the capital of Mexico, which was the venue of the United Nations International Conference on Population and Development, where the policy was first signed by Reagan.

Every Republican president since Reagan has signed the global gag rule into law only for it to be annulled by Democratic presidents Bill Clinton and Barack Obama.

Trump's expanded version of the gag rule blocks all types of US global health funding to non-US NGOs that provide abortion-related services.

"None of us were surprised when the Mexico City Policy came in place again. Every single time we have a Republican president we have a policy like this," said Christine Stegling, executive director of the International HIV/AIDS Alliance. "The big difference is that in the past it only applied to family planning, now it applies to all global health funding. In the past that meant that HIV funding ... wasn't affected by the Mexico City Policy, and now it is."

The policy was one of the first things Trump signed into law after becoming president.

Gagging PEPFAR and global health funding

Trump's new version of the gag rule threatens to withhold PEPFAR funding from hundreds of NGOs that provide, counsel on, or make referrals for abortion.

There are 470 foreign NGOs -- which received $873 million in PEPFAR funding from fiscal year 2013 to fiscal year 2015 -- that are subject to the policy, according to Jen Kates, director of global health and HIV policy at the Kaiser Family Foundation, and who presented on Friday.

Furthermore, another 264 US NGOs received $5.5 billion in PEPFAR funding in the same period and will have to ensure the compliance of the hundreds of global NGOs they sub-contract HIV/AIDS work to, said Kates.

"The expansion of the policy to encompass almost all of US global health funding, including PEPFAR, means that the amount of money and the number of organizations that are affected is much greater than before," Kates told CNN.

Even if governments provide funds and ask organizations to promote or carry out family planning services, those organizations are restricted from performing these services according to the terms of the new global gag rule, lest they lose all their health funding from the US.

At its root, the policy is not only about basic human rights but it's also about issues of sovereignty, according to Brian Honermann, deputy director of amfAR, the Foundation for AIDS Research, who presented at the conference on Friday.

What this means on the ground

Cuts in NGO funding from the US will likely have large-scale impacts on organizations' HIV/AIDS services, as they will no longer have the funding to sustain certain activities, according to Stegling. The International HIV/AIDS Alliance -- which reached 1.6 million people in 36 countries in 2017 -- will lose $60 million over the next three years, forcing the organization to do "less prevention, less community work, less advocacy and less service work," said Stegling.

Already clinics around the world, such as in Mozambique, are closing as a result of the expanded global gag rule; the provision of youth services for HIV/AIDS and sexually transmitted infections (STIs) are being scaled back, according to Honermann.

And while women and girls bear the brunt of the expanded policy as it becomes harder to access sexual and reproductive health services, men also fall victim to the new rule.

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Most NGOs working in HIV/AIDS offer an integrated range of services for men and women, including the prevention and treatment of HIV/AIDS, testing for STIs and other sexual and reproductive health services, and family planning, according to Kates.

In Malawi, where some integrated facilities have also had to curtail certain services because of the new global gag rule, said Stegling, gay men can no longer access the HIV testing services that were previously offered.

The reduction in integrated services offered by NGOs -- what Stegling refers to as "entry points" for HIV/AIDS treatment and prevention -- means "the displacement of patients back into facilities that they don't feel comfortable in, which likely means we are going to lose the ability to recruit them into care, get them onto treatment and save their lives," according to Honermann.

Republican Rep. Chris Smith of New Jersey, a longtime champion of the global gag rule and a supporter of Trump's expansion, wrote , "This executive order demonstrates that the Trump Administration is committed to a consistent, government-wide policy: taxpayer dollars should not fund abortion or the abortion industry -- either domestically or internationally."

Many organizations that provide, among other things, services around sexual and reproductive health, HIV/AIDS treatment and prevention, and STI screening, said Honermann, are set up because many youth won't use government facilities to seek out those services, which often include HIV testing.

Students from the University of the Witwatersrand explain the self HIV testing kit, in Hillbrow, Johannesburg.

Much of the work around HIV/AIDS is carried out in countries where people with the disease are already severely criminalized, said Luisa Orza, the sexual and reproductive health and rights lead at the International HIV/AIDS Alliance.

"They're very marginalized, they're very vulnerable," said Orza, and because of their social precariousness, they often face discrimination at government-run public health facilities.

Media update: #AIDS2018 press conference on the impact of the #GlobalGagRule. With @iasociety President-Elect Anton Pozniak, @KaiserFamFound Vice President Jennifer Kates, @theaidsalliance's Luisa Orza and more. Watch it live here https://t.co/Vn0KC4K5Ra — AIDS 2018 (@AIDS_conference) July 27, 2018

The downsizing and stripping away of integrated services offered by NGOs, which the global gag rule is threatening, is "a massive double-whammy of criminalization," according to Orza.

Many of the most vulnerable populations, including the LGBT community, which is often in need of HIV/AIDS services, will probably be forced out from prevention and treatment, said Stegling.

State Department is monitoring

The review of the PLGHA evaluates the effects of the expanded global gag rule on the delivery of global health assistance through the end of the 2017 fiscal year.

The review highlighted how the US Conference of Catholic Bishops praised the new gag policy for being "one of the most significant policy initiatives on abortion ever taken by the United States in an area of foreign assistance." But the review also emphasized the "potential chilling effect of the policy on global health services in situations in which the application of the policy is unclear."

Various HIV/AIDS experts who talked to CNN claimed that the lack of clarity around the rules of Trump's expanded version of the global gag policy was already causing confusion on the ground. This confusion, according to Gorna, has caused organizations to overreact in some instances, closing down services that don't need to be closed down.

"All of this is a massive distraction of time, energy and resources," she said.

Integrated service provision -- where HIV/AIDS, contraception, pregnancy, STI, and family planning services, among others, are offered by organizations -- is the most effective way to treat and prevent HIV/AIDS in most circumstances, according to Gorna.

By threatening to cut off funding to organizations that offer abortion as a family planning service, the gag rule is pushing organizations to reject this integrated, best-practice approach, say experts. This shouldn't be a political or ideological question, it should be "about good programming," according to Stegling.

The State Department's review wasn't able to evaluate the effects of the extended global gag policy on aid activities related to HIV/AIDS, citing "insufficient time to gauge the impacts."

However, the review did claim that the Department of State intends to monitor the effects of the extended global gag policy on HIV/AIDS, and plans to have another review of PLGHA ready by December 15, 2018.

According to Gorna, US officials are "massaging the impact."

CNN reached out to the State Department's Office of the US Global AIDS Coordinator and Health Diplomacy, which leads the implementation of PEPFAR. The office has not responded to a request for a statement on the issue.

Going forward

While experts have been able to quantify, to an extent, the number of NGOs impacted by the global gag rule, as well as understand how HIV/AIDS services are beginning to be affected on the ground, it's still too early to say specifically how large the impact of the expanded policy will be on the HIV/AIDS epidemic.

The experts in Friday's press conference intimated that it will probably take years to assess how many people will be affected and what the overall toll on human lives will be. The results of this will likely be devastating, said Stegling, but how devastating remains unclear.

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New global movements, such as But the policy could have a positive, if unintended, consequence, according to Stegling.New global movements, such as SheDecides , have formed with the intention of augmenting the rights of girls and women and informing the world of the effects of Trump's gag rule expansion. It has also encouraged the HIV/AIDS community to rethink strategies and more closely band together.

"There's been much more emphasis and conversation about how important it is that women's rights issues are at the center of the response, and how important it is that we come together, whether that's donors, partners or progressive governments," said Stegling. "The global response requires all of us to put up a united front."