From Sci-Fi Wire:

Andy Hallett, who played the green-skinned demon Lorne on The WB's
canceled Angel, told fans on his official Web site that he's been
hospitalized for an undisclosed viral ailment after having to miss a
scheduled convention appearance. "I wish I had better news for you
at the moment; however, I am having a bit of a rough time right now,
medically speaking," Hallett wrote his fans. "As you know, it would
take a lot for me to miss a scheduled event (ya know what a ham I
am ... ) but I'm unable to fly or travel at the moment. Last week I
was hospitalized due to a minor viral infection that was complicated
by exhaustion. This minor problem turned 'not so minor' quite
quickly and was causing major problems with my lungs and breathing."

Hallett added that he was in the intensive care unit in Los Angeles'
Cedars-Sinair Medical Center for five days. But he added that his
doctors expect a "speedy recovery." "I just have to rest, rest,
rest, rest, rest, rest." Hallett said.