The rate of infection is also lower in the long run.
So far this year, she said, the infection rate is running at 80 percent.
For the age group overall, the new infection rate was 4.4 percent.
The infection rate there is now one new person per minute.
The lower number is still considered an extremely high rate of infection.
The greatest rate of infection is among people from 18 to 25.
Southern African infection rates are 30 times those in the north, he said.
Health officials say the infection rate may surge past 30 percent if nothing is done.
Another potential reason is a high infection rate in Haiti.
Without that first line of defense, experts can only guess at the reasons for the low infection rate.