Meanings of hospitalized under in английском

The suspect was captured Friday night and remained hospitalized under guard in Boston.

Dzhokhar Tsarnaev, 19, was arrested late on Friday after an extensive manhunt and remains hospitalized under guard.

He remained hospitalized under evaluation, police said.

We compared the socio-demographic and clinical outcomes as predictors in severely ill hospitalized under-five diarrheal children with and without pneumonia.

As a result, I have been forced to remain here in Tokyo, hospitalized under doctor's orders (and only doctor's orders?)