The government's worst-case scenario forecast for the Ebola epidemic in West Africa won't happen, a U.S. health official said Wednesday.

In September, the Centers for Disease Control and Prevention estimated the number of people sickened by the Ebola virus could explode to as many as 1.4 million by mid-January without more help.

Things have changed. On Wednesday, CDC Director Dr. Tom Frieden said, "We don't think the projections from over the summer will come to pass."

Frieden did not provide new estimates. He was speaking in Washington at a U.S. Senate hearing on preparedness and response to public health threats.

The earlier projection was a worst-case scenario for reported and unreported illnesses in Liberia and Sierra Leone, based on conditions in late August - before an international surge in medical aid and supplies. That seems to have helped slow the epidemic in Liberia, one of the three hardest-hit countries. However, the epidemic has been fierce lately in Sierra Leone; it remains unpredictable in Guinea,

When he released the Ebola projections two months ago, Frieden said he was confident the most pessimistic numbers would not occur. Since then, "there has been very effective intervention with USAID, ourselves, the global community, and most importantly the countries and the communities most affected," he said Wednesday.

Since spring, there have been more than 14,000 Ebola cases and more than 5,100 deaths in the epidemic, according to World Health Organization figures.

Frieden said the CDC thinks that now between 1,000 and 2,000 new cases are occurring in West Africa each week. That seems to be in the neighborhood of the CDC's best-case estimates for the epidemic by mid-January.

Also on Wednesday, a Pentagon spokesman said the U.S. military is scaling back the size and number of Ebola treatment facilities it is building in Liberia from 17 to 10 centers.