(CNN) -- Josh Hardy, the 7-year-old boy whose parents fought to get him an experimental antiviral drug, is recovering well -- sitting up on his own and even taking a few steps with the help of a walker and his parents' supportive arms.
"He's getting stronger every day," says his mother, Aimee Hardy. "We're completely optimistic and hopeful that he'll make a full recovery with no disabilities."
Josh was in critical condition and near death in March when the drug company Chimerix denied him the use of its drug brincidofovir. A few days later, following reports by CNN and intense pressure from social media, Chimerix reversed course and allowed Josh and other patients like him to become part of its clinical trials.
Josh was released from St. Jude Children's Research Hospital in Memphis, Tennessee, last month but continues to receive care there.
He, his parents and three brothers, who live in Virginia, are now staying at an apartment near the hospital. His mother says he won't be healthy enough to return home until next month at the earliest.
Before receiving brincidofovir, an adenovirus was ravaging Josh's immune system, left vulnerable by treatment for cancer, and the only available antiviral drug to treat it wasn't working.
Once he started taking brincidofovir, the adenovirus was gone from Josh's blood in two weeks. "It's truly a miracle drug," his mother says.
While the adenovirus has disappeared, Josh is still suffering the effects of the medication his doctors gave him as a second-choice drug when he wasn't allowed to take brincidofovir. He now receives blood transfusions once a week and dialysis three times a week. He has to be fed intravenously.
But there are signs his kidneys are beginning to work.
"On Easter Sunday he peed 110 milliliters at one time and I said, 'Oh, thank you!' " his mother says.
Traditionally, drug companies have not been allowed to treat so-called "compassionate use" patients such as Josh as study subjects, so helping them out has been pure charity work on behalf of the drug company.
But the Food and Drug Aministration allowed Chimerix to use data from Josh and others as part of its application to the agency, helping to get the drug on the market faster.
The Hardys said they were saddened to hear that Kenneth Moch, who as president of Chimerix initially denied them the drug but eventually helped Josh get it, is no longer with the company. According to Chimerix, Moch resigned "to pursue other interests."
"I feel terrible. I feel like it was our fault," Aimee Hardy says. "He's a genuine guy who was just put in a bad situation."
Moch says he's looking for a new job.
"The Hardy family should feel no responsibility for this whatsoever, and I appreciate their kind thoughts," Moch says. "I'm collateral damage from a very complex situation."