Why does anti-vaxx have two x’s?

As far as I can tell, the double-x did not infiltrate the English language until the internet went mainstream ( Exxon might be the exception —a company name deliberately chosen to be inscrutable and inoffensive). The earliest example I can think of is &ldquo; anti-vaxx &rdquo;, as in &ldquo;anti-vaccine&rdquo; (see also &ldquo;antivaxxer&rdquo;). Then we got &ldquo; doxxing &rdquo; (to publish…