The deadly coronarvirus may not be infectious enough to pose a global threat, researchers claim.
Their analysis of 55 cases of Middle East respiratory-syndrome coronavirus, indicated the virus struggled to spread in people.
But the virus may be mutating, which means it could become a much greater threat.
It is similar to viruses that cause Sars and the common cold.
So far there have been 77 confirmed cases and 41 deaths.
Most infections come from an unidentified animal source, but there have been cases in which the virus has spread between people.
The team at the Pasteur Institute in Paris tried to calculate the average number of people each infected person passed the virus on to - what is known as a "basic reproduction value".
A high value means the number of cases can increase rapidly and potentially spread around the world, but a number less than one would mean the virus was destined to fade away.
The study indicated each patient would, on average, infect 0.69 others. So three infected patients would pass the virus on to just two people.
Prof Arnaud Fontanet told the BBC that the virus currently is not able to start an epidemic.
In the early stages of Sars in late 2002 it had a basic reproduction value of 0.8, but eventually the virus mutated and could spread more easily.
The findings are published in the Lancet.