Virus Variant From South Africa Detected In U.S. For First Time

The South African coronavirus variant has been detected in the US, specifically in South Carolina, where two cases have been identified. These cases are not connected and lack recent travel history, suggesting possible undetected cases in the state. Scientists are concerned that these new strains might reduce the effectiveness of current vaccines.

What does the lack of recent travel history suggest about the identified cases?

What do scientists worry about regarding the new strains of coronavirus?