A woman dubbed a "New York patient" by scientists at New York-Presbyterian Weill Cornell Medical Center in New York City has beaten the virus after receiving a rare but dangerous stem cell treatment.
She is the fourth person ever cured of HIV - the previous three were all men - and experts have found two cases of women beating the virus naturally.
The woman was also a cancer patient and received a treatment that is supposed to fight both diseases at once - but is also so risky that it is considered "unethical" to use it on people who do not have a terminal cancer diagnosis.
To carry out this treatment, doctors must first find a donor who has a rare mutation that makes him resistant to the virus.
Experts tell NBC that people who have this mutation are usually northern Europeans, and even then, only one percent of the population has it.
Doctors then perform a "haploidentical umbilical cord transplant," which uses cord blood and bone marrow from the donor.
The cord blood helps fight blood-based cancers - like the leukemia the woman suffered from - while the bone marrow supplies the body with stem cells.
Because cord blood is generally not as effective in adults as it is in children, stem cell transplantation can help increase its effectiveness.
The role of adult donor cells is to speed up the early transplant process and make the transplant easier and safer," Dr. Koen van Besien, one of the lead physicians who studied the New York patient, told NBC.
Because this stem cell treatment can often lead to the patient's death, experts will not use it on a healthy person who can manage their HIV infection with normal methods.
Instead, they focus this treatment on people in the final stages of a cancer diagnosis who are likely to die anyway unless major medical intervention is performed.
The researchers say that of the more than one million Americans struggling with HIV, as many as 50 patients could receive the treatment each year.
The woman in question was diagnosed with HIV in 2013 and leukemia in 2017, making her a potential candidate.
She received the treatment four years ago. Since then, her cancer has gone into remission and her HIV treatment was discontinued last winter.
Her body responded well to the treatment, doctors report, and she quickly saw positive results.
Although she stopped HIV treatment more than a year ago, the virus has not returned in her. Repeat scans of her body show no HIV cells with the potential to replicate.
They also took cells from her body and tried to infect them in a lab, which was unsuccessful.
If a few more years pass and doctors still can not find HIV in her body or infect her cells, they can confidently declare her "cured" of the virus.
"I am thrilled it turned out so well for her," Dr. Yvonne Bryson told NBC.
She added that the New York patient's case has brought "more hope and more options for the future" of HIV treatment.