Low doses of a MERS antiviral drug can actually speed up the virus instead of stopping it.

Protease inhibitors are designed to jam the machinery a virus needs to replicate itself inside a human host. These specific MERS-CoV drugs exhibit a dangerous behavior where a weak concentration triggers the very enzyme it is supposed to kill. Instead of acting as a partial cure, a low dose provides a chemical boost that helps the virus spread faster. This counterintuitive activation highlights a massive risk in drug design and patient dosing schedules. Doctors must ensure that drug levels never dip into this activation zone or they might inadvertently fuel the infection.