Health experts in Texas are observing up to 18 people including children who have had contact with the first person to be diagnosed with the deadly Ebola virus in the United States.
The patient is said to have fallen ill after flying from Liberia to the US to visit family two weeks ago.
The children in question are being monitored at home for any signs of the disease.
“I know that parents are extremely concerned about that development, but let me assure you that these children have been identified and they are being monitored and the disease cannot be transmitted before having any symptoms,” said Texas Governor Rick Perry in a press statement.
Health officials in the US say they have the medical infrastructure to prevent an outbreak of the virus.
But with no known cure for Ebola pharmaceutical companies are fast tracking experiments on potential vaccines.
According to the World Health Organisation Assistant Director-General Dr. Marie Paule Kieny, two vaccines are looking hopeful.
“One is based on what is called chimpanzee adenovirus, which is a recombinant viral vector. This is developed by the company GSK. The other one is based on another virus which is called VSC ( Vesicular Stomatitis Virus which in the same family as rabies in cattle) and is being developed by a company in the US called Newlink.”
So far more than 3,000 people have died of Ebola in West Africa – most of the victims have been in Liberia.
A small number of US aid workers have recovered after being flown home.
The man being treated in Texas is said to be in a serious condition.