In response to the Ebola outbreak linked to scores of deaths, the CDC is blocking entry to the U.S. from people who have been in Ebola-affected African nations.

Non-U.S. passport holders will not be allowed entry if they've spent any time in the prior 21 days in the Democratic Republic of the Congo, Uganda, or South Sudan, regardless of country of origin.

The order, invoked under the public health law Title 42, "is necessary to protect the health of the United States from the serious risk posed by the introduction of Ebola disease into the United States," said the order signed by Jay Bhattacharya, MD, PhD, the senior official carrying out the duties of CDC director.

The order will take effect for the next 30 days.

As of Monday, more than 300 suspected cases and 118 deaths in Congo and one death in neighboring Uganda have been linked to the large Ebola outbreak that the World Health Organization (WHO) has declared a public health emergency of international concern (PHEIC). The current outbreak is caused by the Bundibugyo strain, which has no approved vaccines or therapies.