It starts with a slight scratchiness at the back of your throat.

Then, a sneeze.

Then coughing, sniffling and full-on congestion, with or without fever, for a few insufferable days.

Viral upper respiratory tract infections – also known as the common cold^[1] – afflict everyone, typically three times per year^[2], lasting, on average, nine days.

Colds don’t respond to antibiotics, and most over-the-counter medications deliver...