At this very moment a vast world exists that’s free of the coronavirus, where people can mingle without masks and watch the pandemic unfold from thousands of miles away.That world is Antarctica, the only continent without Covid-19. Now, as nearly 1,000 scientists and others who wintered over on the ice are seeing the sun for the first time in weeks or months, a global effort wants to make sure incoming colleagues don’t bring the virus with them.From the UK.’s Rothera Research Station off the…