In an Oct. 15 letter posted on his Facebook page, the 73-year-old cardinal expressed "heartfelt gratitude to all those who have prayed for my recovery" and said "words cannot adequately express" the joy he felt in being able to celebrate Mass again.
The cardinal also asked for continued prayers, noting that his "recovery continues to remain an intensive process" and that "Divine Providence will determine the time of my return to my usual pastoral activities."
He said his letter was not mainly to update friends and supporters on his health condition but to encourage people to say the rosary each day.
He stressed that the month of October is dedicated to this devotion and that in her messages in the apparitions at Fatima in Portugal, Mary urged people to daily pray the rosary, specifically praying for peace.
This prayer for peace, he said, is for "peace in your soul, peace in the world, peace in the church."
In a previous letter he wrote Sept. 25, Cardinal Burke said he has continued to recover in a house near family members in Wisconsin since his release from the hospital Sept. 3. A native of Richland Center, Wisconsin, in the La Crosse Diocese, he has not disclosed where he was hospitalized.
"Although I am making steady progress, it is slow," his previous letter said. "The doctors and therapists who direct the program of rehabilitation assure that it is necessarily so and that I am doing well."
He said he was "trying to grow in patience" as he regained "certain fundamental physical skills needed for my daily living, and overcoming a general fatigue and difficulty in breathing."
The cardinal has not announced whether he received the COVID-19 vaccine.
The Vatican had started offering all Vatican residents, retirees and employees the vaccine developed by Pfizer and BioNTech in mid-January 2021. The cardinal was eligible for the vaccine as a member of the College of Cardinals and a member of the Apostolic Signatura, which he led as prefect from 2008 until his resignation in 2014.
Cardinal Burke has expressed concerns about the COVID-19 vaccines, including that it is "never morally justified to develop a vaccine through the use of the cell lines of aborted fetuses. The thought of the introduction of such a vaccine into one's body is rightly abhorrent."
He also said the "vaccination itself cannot be imposed, in a totalitarian manner, on citizens."
In December, the Vatican Congregation for the Doctrine of the Faith, citing church teaching, said that when alternative vaccines are not available, it is morally acceptable to receive vaccines developed or tested using cell lines originating from aborted fetuses, in this case, including COVID-19 vaccines.
The Pfizer and Moderna vaccines did not use abortion-derived cell lines in developing or producing their vaccines, but they did in lab testing.
Cardinal Burke served as bishop of the Diocese of La Crosse from 1995 to 2004, as archbishop of St. Louis from 2004 to 2008, and as prefect of the Vatican Apostolic Signature from 2008 to 2014.
While the cardinal often resides in Italy, he travels extensively and was in the United States at the time of sharing the news about his having contracted the virus.