The CNN anchor is still working and aired his x-ray Monday night during his show ... and Dr. Sanjay Gupta joined him to evaluate the state of Chris' lungs. Gupta says there's definite signs of inflammatory fluid build-up ... a tell-tale sign of coronavirus.

Chris passionately explained how he's doing everything he can at home to avoid going to the hospital and adding one more patient to an already-flooded and overworked healthcare system in crisis at the moment. Sounds like what he's doing -- on his doctor's advice -- might well be working.

He told viewers he's constantly moving -- getting up, laying on his side, stretching, talking, whatever -- to keep the virus on its toes, 'cause he says it's banking on people becoming sedentary and passive as it sets up shop in the body ... particularly in the chest.