The cardinal posted the following on Twitter Tuesday night:

Stay tuned. There’s no further word yet on where he’s being treated or whether he has been vaccinated.

It is known, however, that he has been outspoken about the virus: 

In his sermon on Dec. 12, U.S. Cardinal Raymond Burke, who serves on the highest court at the Vatican, said that “Marxist materialism” seems to have corrupted America’s “governing power,” and that “certain forces, inimical to families and to the freedom of nations” are using the COVID-19 pandemic “to advance their evil agenda.”

He also posted on his blog last year a lengthy statement on the coronavirus:

Certainly, we are right to learn about and employ all of the natural means to defend ourselves against the contagion. It is a fundamental act of charity to use every prudent means to avoid contracting or spreading the coronavirus. The natural means of preventing the spread of the virus must, however, respect what we need to live, for example, access to food, water and medicine. The State, for instance, in its imposition of ever greater restrictions on the movement of individuals, provides that individuals can visit the supermarket and the pharmacy, with the observance of the precautions of social distancing and of use of disinfectants on the part of all involved.

In considering what is needed to live, we must not forget that our first consideration is our relationship with God. We recall the words of Our Lord in the Gospel according to John: “If a man loves me, he will keep my word, and my Father will love him, and we come to him and make our home with him” (14, 23). Christ is the Lord of nature and of history. He is not distant and disinterested in us and the world. He has promised us: “I am with you always, to the close of the age” (Mt 28, 20). In combatting the evil of the coronavirus, our most effective weapon is, therefore, our relationship with Christ through prayer and penance, and devotions and sacred worship. We turn to Christ to deliver us from pestilence and from all harm, and He never fails to respond with pure and selfless love.

Meanwhile, Mike Lewis, found this quote last year:

“There is now a certain movement to insist that now everyone must be vaccinated against the coronavirus COVID-19 and even that a kind of microchip needs to be placed under the skin of every person, so that at any moment he or she can be controlled by the State regarding health and about other matters which we can only imagine.”

Please keep the cardinal and all who love him in your prayers.

UPDATE: NCR’s Brian Fraga has more details and context: 

Burke did not say if he had recently been feeling ill or not. He resides in Italy, but travels frequently, and appears to have been in Wisconsin when he contracted the virus.

The cardinal also did not say whether he had been vaccinated for COVID-19. In previous remarks, homilies and speeches, Burke has raised concerns about the way governments have handled the virus and vaccines in ways that echo far-right conspiracy theories.

In a Dec. 12, 2020, homily, the cardinal referred to the coronavirus as the “Wuhan virus,” a derogatory nickname former President Donald Trump used to refer to the first reported cases of the virus in Wuhan, China.

Burke also said the virus “has been used by certain forces, inimical to families and to the freedom of nations, to advance their evil agenda.”

“These forces tell us that we are now the subjects of the so-called ‘Great Reset,’ the ‘new normal,’ which is dictated to us by their manipulation of citizens and nations through ignorance and fear,” said the cardinal.