Remember the Theranos scam? No, even though a drop of blood can't diagnose 300+ of diseases, scientists say your smell can. And that's the future in medical diagnosis.
It's not all theory either. Animals can be trained to sniff and separate any type of infected people from other healthy ones.
Title : Deep Nose.
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https://nautil.us/issue/95/escape/the-doctor-will-sniff-you-now
https://nautil.us/issue/95/escape/the-doctor-will-sniff-you-now