Vonn spoke briefly after her downhill training run Thursday in which she started fast but held back coming down the bumpy and twisty course to finish 3.98 seconds off the leading time by Lara Gut of Switzerland.
"I'm really excited to be back, feeling good, feeling happy and strong," said Vonn, a week after resuming ski training following her break.
The four-time overall World Cup champion left the circuit in mid-December for three weeks to fully recover from her illness. She missed six races.
Vonn says the break was "important for me because after being sick my legs just weren't strong anymore. At some point you have to listen to your body."
She plans to have another training run Friday before competing in the downhill and a super-G this weekend.
After being hospitalized for two days in November, Vonn won three straight speed races at Lake Louise, Alberta. She won another super-G the following week in St. Moritz, Switzerland.
Vonn then struggled in France, however, crashing in a downhill at Val d'Isere and failing to finish the opening run of a giant slalom at Courchevel. She flew back to the United States the following day to fully recover.
Vonn focused on fitness training and returned to practicing on snow last week in Hinterreit, Austria.
"It feels awesome. It's great to see all the girls on the World Cup," Vonn said. "I am excited to be here, excited to be racing again."
The American won the downhill and a super-combined event when the women's World Cup last stopped in St. Anton in December 2007. She won her first overall title that season.
Vonn plans to have another training run on Friday, but bad weather including overnight snowfall is forecast.
"Hopefully we'll get a training tomorrow and I get comfortable on this course," Vonn said. "I think everybody feels tired at the end of this course, but I feel strong again and everything is good."
Friend and rival Maria Hoefl-Riesch of Germany, who beat Vonn by three points for the overall title in 2011, is happy for the American to be back.
"But this is not an easy race for Lindsey getting back to the World Cup," Hoefl-Riesch said. "It's bumpy from top to bottom, there is no section where you can really charge. This is a difficult course, even for Lindsey."