The MERS coronavirus has caused disease outbreaks across the Arabian Peninsula and spread to Europe several times. The severe pneumonia virus has claimed the lives of several hundred people since its discovery in 2012. For a long time, scientists have been puzzled over how easily the pathogen spreads from human to human. An international team of researchers led by virologists from the University of Bonn have now come to the conclusion, through direct observation, that the rate of human transmission is low. Still, a third of infected persons with symptoms die. The results are now being presented in the renowned New England Journal of Medicine.

The “Middle East Respiratory Syndrome Coronavirus” (MERS-CoV) was detected for the first time in 2012 on the Arabian Peninsula from where it spread to Europe and the USA, among other places. The virus causes severe acute lung infection. A total of at least 856 cases of illness have been registered in the meantime and at least 241 people have died. Scientists are puzzling over how infectious the disease is and how high the estimated number of unrecognized cases is. To date, there have been only theoretical projections.

For the first time, an international team of scientists led by Professor Christian Drosten at the Institute of Virology has been able to directly determine the rate of infection. “The transmissibility of the virus and the estimated number of unknown cases are low,” says Prof. Drosten, summarizing the results. In Saudi Arabia, after new infections occurred, the researchers tracked how the disease spread further in the patients’ home environments. A total of 280 people who lived in the households of 26 infected persons were examined. There was an infection in not more than twelve cases (four percent). “Since each infected person infected significantly fewer than one additional person, it can be assumed that the MERS virus will not cause a pandemic,” concludes the virologist. A disease spreads rapidly only if each infected person infects several other people.