An Australian Olympic gold medalist swimmer has been hospitalized with COVID-19.

Madison Wilson, who is fully vaccinated against the virus, announced on social media that she had tested positive for COVID and was being treated at a hospital.

"It’s been a crazy few months and I believe being run down physically and mentally may have made me more susceptible," Wilson captioned a picture of herself in the hospital. "I feel extremely unlucky but I do believe this is a huge wake up call, Covid is a serious thing and when it comes it hits very hard."

Although the COVID-19 vaccine is highly effective, people who are vaccinated can still contract the disease, which is known as breakthrough infections.

"I’d be stupid not to say I wasn’t scared," Wilson said. "I’m so lucky for all my family, friends and support people. I can’t believe how much love I have been shown and I’m forever in debt to these people."

Wilson said she will "take some time to rest."

At the Tokyo games, Wilson took home the gold in the women's 4x100 freestyle relay and won bronze in the 4x200 freestyle relay, the Associated Press reported.