So the Babylon Bee tweets that Trump is building a Coronavirus-proof wall, and some guy tweets about a YouTube video of viruses climbing "tiny little ladders:

BREAKING: YouTube Video Shows Coronavirus Using Tiny Ladder To Scale Trump's Wall https://t.co/6b1GtvtnqN

— Elvis Trump (@Elvis_Trump) March 5, 2020

Here's something I wrote (under the heading of Mexican Flu And Little Tiny Backpacks) during the 2009 flu pandemic in Mexico, which of course crossed into the US because no one tried to stop it:

On Marginal Revolution Tyler Cowen, the economist, says that  "Even a completed fence would not stop a virus..." In fact, diseases require vectors—the viruses are not hiking through the Sonoran Desert, wearing little tiny backpacks, carrying little tiny waterbottles, and singing Mexicanos, al grito de guerra in little tiny voices that you can't hear because they're only 200 nanometers tall.

The viruses come in with people, and an unguarded border that lets millions enter without inspection every year isn't helping.

Viruses need hosts, and stopping people coming stops the virus coming.