The Grand Ayatollah Sistani, the Supreme Religious authority for Shia Muslims, responded to a religious question about the conditions for holding congregational prayers in mosques as for maintaining social distance in the situation of Corona.
What follows is the the question and its answer by Ayatollah Sistani:
In order to [safely] hold congregational prayers in mosques and other places of worship, government officials in our country require congregants to keep a distance of two meters (approximately 6 feet) between adjacent individuals in any given row, and that a vacant row should be included between one row and another. Therefore, can congregational prayer take place under such conditions (i.e., is it valid) according to the rulings of His Eminence al-Sayyid al-Sistani?
May the peace, mercy and blessings of Allah be upon you.
A [maximum] distance of 120 cm (approximately 4 feet) is permissible between a prayer congregant and the person standing next to them in the same row and between the place of prostration of a given row and where congregants stand in the row ahead of them. A distance of two meters [between congregants], as described in the question, is problematic for the establishment of a valid congregational prayer.