Reply to "Comments on Fouchier's calculation of risk and elapsed time for escape of a laboratory-acquired infection from his laboratory"

In a letter to the editor, Dr. Lynn C. Klotz challenges my conclusion that laboratory-acquired infections (LAIs) are expected to occur at an extremely low frequency in facilities such as those used at ErasmusMCfor studies on airborne transmission of influenza viruses between ferrets and that these studies pose negligible risks to humans and the environment. Unfortunately, Dr. Klotz does not provide a scientific justification of how the numbers should be adjusted based on the biosafety measures that are in place in these facilities, which is the key challenge in this debate.

Dr. Klotz suggests that incidents at the U.S. CDC laboratories and the long history of escape of LAI agents and other escapes from laboratories show that my estimates of the likelihood of LAIs occurring at the Erasmus MC facility are too low. However, it is unclear to me how the incidents at the U.S. CDC—which did not lead to LAIs—would affect my calculations. In addition, I have pointed out previously that historical data on LAIs do not take into account the specific pathogen types or the numerous biosafety measures that are in place to mitigate the risks in laboratories where transmission research is conducted. [...]