I just received an email from Vivaticket stating that tickets for Cenacola Vinciano between the dates of March 6-12 will be refunded upon request. They will deposit the money directly into our bank account upon provision of the IBAN and SWIFT code. We decided that we would prefer to simply ask that it be sent to the church Santa Maria delle Gracie as a donation. (This is not entirely out of generosity; I don't think our little credit union will accept a foreign wire deposit. I know they don't do outward transfers.)
This email was sent well prior to the announcement of the "shut down" for much of northern Italy through April 3, including museums in MIlan. So if you have tickets for later in March I would expect you will receive the same announcement later.