WHO have a few symptoms noted. Namely fever, cough and pneumonia like symptoms. Bacterial pneumonia often comes with phlegm. And it is my understanding that bacterial phlegm is usually yellow to green in colour.

 

So would it be fair to say that if there is green to yellow phlegm associated with chest infection, it is unlikely to be COVID-19? Can anyone with medial training expand. I can't find any real answers in my online search.

You cannot tell by sputum color.

 

COVID-19 would be suspected in someone with evidence of a viral pneumonia (determined by Xrays, blood tests, physical exam) especially if they have history of travel to china or contact with people from there.

 

However most people with COVID have only minor illness without pneumonia, some have no symptoms at all.