"Every ecclesial precautionary measure must take into account not only the common good of civil society, but also of that unique and precious good which is faith, especially that of the least ones," he said.
The vicar general exhorted Catholics to follow the Italian government's quarantine measures until April 3, and to stay at home.
"Coronavirus infection is spreading exponentially. In a few days the number of infected doubles, and at this rate it is not difficult to predict that in two months it will reach the order of tens of thousands of people only in Italy," De Donatis wrote in his letter.
"There is a clear risk of collapse of healthcare facilities, in which there are already many on ventilators, above all because of the disproportion between the available intensive care resources and the growing number of patients. A large number of people could die, especially the elderly and vulnerable people," the vicar of Rome said.
There are 242 confirmed cases of COVID-19 currently in Lazio, the region surrounding Rome, as of March 13, according to the Italian Ministry of Health.
Coronavirus cases in Italy have grown quickly in recent weeks surpassing 17,500 documented cases. More than 1,250 people have died from COVID-19 in the country since Feb. 22.
A nationwide quarantine has been declared in Italy through April 3 in order to slow the spread of the coronavirus pandemic.
The quarantine restricts movement within Italy and requires people to stay in their homes except for cases of absolute necessity, which may include going to work, to the pharmacy or hospital, or to the supermarket.
On March 11, Italy's Prime Minister Giuseppe Conte tightened the restrictions of a nationwide lockdown to include the closure of all restaurants, bars, and non-commercial businesses other than supermarkets.
In all cases, a distance of one meter must be maintained between people in public. Not following these regulations is punishable by fine or arrest.
The previous Diocese of Rome decree suspending all public Masses in the diocese until April 3 still stands, however now Catholics will once again have access to some parishes for private prayer.
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"The spiritual need of the people of God to gather to celebrate the Eucharist becomes for us Christians the object of a painful renunciation. There is first the spiritual need for the charity of caring for our brothers. Unfortunately, going to church is no different than going to other places: it is at risk of contagion," De Donatis wrote.
Courtney Mares is a Rome Correspondent for Catholic News Agency. A graduate of Harvard University, she has reported from news bureaus on three continents and was awarded the Gardner Fellowship for her work with North Korean refugees.