They also may have long-term toxicities, but there is little data on the long-term effects of taking these drugs early in life, which is another reason why it worries doctors to prescribe them unnecessarily, he said.
"What if we found out one of these medicines increased the risk of developing cancer in 20 years?" Kline said. "It's one of the reasons we reserve this therapy only for infants who have confirmed infection. Then, you say to yourself, even if there are long-term effects of medication, that's unlikely to be worse than having HIV."
Gay and her colleagues operated under the assumption that the baby was infected, and it's fortunate that they made the right call, said immunologist Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases.
"You don't want to be inappropriately treating babies if they're not infected," said Fauci, a pioneer in HIV and AIDS research. "You don't want to put them at risk."
Did the Mother Give Informed Consent?
Gay said in an email last March that the baby's mother told her to "please do whatever you need to do to keep my baby healthy."
Because the baby wasn't part of a study, there was no need to require the mother to sign a consent form for her child's treatment involving nonstandard medication use, Gay said.
Indeed, the 2013 HIV guidelines from the National Institutes of Health indicate that added drugs beyond standard of care can be used in "other scenarios" but should "be accompanied by counseling of the mother on the potential risks and benefits of this approach."
"It certainly was not the complete education that I like to give to moms before initiating therapy, but considering that she had only learned that day of her own diagnosis, I knew that it would be impossible for her to understand all of the pathogenesis of HIV within the time limitations that we had," Gay said in an email.
This was complicated by the fact that the baby's mother did not accompany the baby to the University of Mississippi Medical Center. Instead, she stayed behind at the hospital where she'd given birth.
"Physical location doesn't make it any the less important to secure her express permission to an off-label use in a circumstance where they're not certain the baby really has the disease," Caplan said. "In general, you don't want to do anything and everything you think of on the basis of an open-ended or vague consent."
Still, Caplan and Kline said they believe Gay had the patient's interests at heart, and that she had the right to deviate from standard of care.
When Did They Find the 'Cure'?
The baby continued the three-drug regimen for the next 18 months, until the baby's mother stopped taking her to clinic appointments, bringing treatment to a halt, Gay has said. It is not clear why they stopped coming to appointments or why they resumed.
The 2-year-old spent five months off treatment before returning to Gay, at which point the doctor expected to see test results showing high viral loads. Instead, the child's HIV appeared to have remained at almost undetectable levels.
"I did not expect that this baby would turn out to be a cure," Gay said in last March's news conference. "That was a surprise to me."