Countries worldwide are scrambling to address the spread of the omicron variant. Part of that response has included travel restrictions.The U.S. has restricted travel from a number of countries in Southern Africa. Similar restrictions have been made by countries in Europe and Asia despite, the fact that the variant was in the Netherlands a week before it hit South Africa. The World Health Organization is also urging those age 60 or over and other vulnerable people to avoid air travel.What do these new rules mean? And how effective are these travel advisories?