Hader was placed on the COVID-19 injured list Monday.
According to Adam McCalvy of MLB.com, Hader tested positive for the virus, so he'll be sidelined for at least the next 10 days. Depending how long he's out, Hader could require a rehab assignment before retaking the field for the Brewers. Devin Williams is the most likely candidate to receive save chances in the meantime.