COVID-19 Test Navy sailors embarked with the medical treatment facility aboard Military Sealift Command hospital ship USNS Mercy conduct rapid COVID-19 antigen testing on the pier during Mercy Exercise 21-4 in San Diego, Sept. 13, 2021. MERCEX 21-4 is a week-long, pierside training evolution that culminates in a capstone emergency scenario. Mercy can steam to assist and provide relief as a symbol of Navy Medicine’s abilities around the world. SHARE: Download: Full Size (2.89 MB) Tags: Navy, coronavirus Credit: Navy Petty Officer 2nd Class Jake Greenberg VIRIN: 210913-N-DA693-1001A.JPG Photo Gallery