(Bloomberg) -- The Centers for Disease Control and Prevention has ordered airlines to provide the names of passengers arriving in the U.S. who have traveled to southern Africa in recent days as it assesses the potential spread of the omicron variant of the coronavirus, according to two people familiar with the action.  

The CDC told carriers that they must provide the information to allow for contact tracing in a letter sent Tuesday, according to the people. The airlines had been told to collect potential contact-tracing data in an order last October. 

While scientists are still assessing the potential dangers of the omicron variant, there are fears that its multiple mutations might make it more transmissible or able to side-step protections from vaccinations. 

CDC didn’t immediately respond to a request to comment on the action. The White House decline to comment. 

Omicron cases have been identified in more than 20 nations, including in Europe, Canada and Australia.

The order was earlier reported by Reuters.

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