Of the 16 new diagnosed cases, 15 service members have returned to duty in Iraq, the Pentagon said.
Joshua Vallow, 7, and Tylee Ryan, 17, were last seen in September.
The man was taken into custody by Prince George's County police responding to reports that a driver had struck multiple vehicles.
"This is a very fast moving, constantly changing situation," Health and Human Services Secretary Alex Azar said.
Unless the Senate alters its rules, Lev Parnas' GPS device will likely make his attendance in the Senate Gallery impossible.