THE HAGUE, Netherlands (AP) With each passing hour, new restrictions were being slapped on travel from countries in southern Africa as the world scurried Saturday to contain a new variant of the coronavirus that has the potential to be more resistant to the protection offered by vaccines.

A host of countries, including Australia, Brazil, Canada Iran, Japan, Thailand and the United States, joined others, including the European Union and the U.K. in impose restrictions on southern African countries in response to warnings over the transmissability of the new variant against the advice of the World Health Organization.

Despite the shutdown of flights, there was increasing evidence that the variant is already spreading. Cases have been reported in travelers in Belgium, Israel and Hong Kong, and Germany also has a probable case. Dutch authorities are checking for the new variant after 61 passengers on two flights from South Africa tested positive for COVID-19.

The global health body has named the new variant omicron , labeling it a variant of concern because of its high number of mutations and some early evidence that it carries a higher degree of infection than other variants. That means people who contracted COVID-19 and recovered could be subject to catching it again. It could take weeks to know if current vaccines are less effective against it.