AS THE newly identified coronavirus that has just turned up in
London re-emphasises (see article), new diseases—and new
versions of old diseases—can appear suddenly, apparently from
nowhere. Developing and deploying vaccines against such
novelties takes time. If a lethal strain of flu, or something
else equally deadly, were to emerge, that delay could cost a lot
of lives. A second line of defence that took effect immediately
would therefore be desirable. And, as they report in Molecular
Pharmaceutics, David Jackson of the University of Melbourne and
his colleagues think they may have found one. They are working
on a way to create a universal virus shield at the point of
entry used by most respiratory viruses: the nose.  A traditional
vaccine works by stimulating what is known as the adaptive
immune system. This is the part that adjusts itself to pathogens
encountered by the body, and crafts specific responses to them.
But the immune system has a second, generic arm, known as the
innate immune system, that is