Jack Osbourne in "Fantastic" Spirits After Multiple Sclerosis Diagnosis

Jack and Sharon Osbourne at the Tribeca Film Festival LA Reception on March 21, 2011 in Hollywood, California. Credit: Alexandra Wyman/WireImage

Jack Osbourne is a fighter.

Since going public with his multiple sclerosis diagnosis earlier this month, the 26-year-old has been in "fantastic" spirits, according to his mom, Sharon, 59. "He is very, very strong," The Talk co-host told Us Weekly at the 39th Annual Daytime Emmy Awards in Beverly Hills June 23.

"The outpouring [of support] for Jack has been amazing, and it really picks you up and gets you back into reality when you see how many people care and are concerned," Sharon continued. "It makes you feel really strong."

Jack went blind in one eye as a result of the autoimmune disease, which affects the brain and spinal chord; MS can also cause problems with muscle control, vision, balance and thinking, but affects each patient differently.

Luckily, Jack's vision is "back to about 80 percent now," he said on The Talk recently. "They don't know if it will ever improve beyond that, but everyone's different."