The coronavirus is still circulating and mutating — case in point, the World Health Organization has designated a new variant of concern, called omicron. The variant appears to have some characteristics that may make it more transmissible than others, but much about it is still unknown. NPR health correspondent Allison Aubrey talks with Emily Kwong about how researchers and public health experts are racing to learn all they can about it — including how transmissible it actually is and how it responds to current vaccines. They also talk travel bans, a weak tool in preventing viral spread that may even penalize information sharing.