A modified vaccine for a deadly virus is now a 'select agent'

The US Centers for Disease Control and Prevention has reclassified a modified Junín virus vaccine as a "select agent." This means anyone working with this specific vaccine strain must now follow strict federal rules for handling dangerous pathogens.

The Junín virus causes Argentine hemorrhagic fever, a severe and often fatal disease. This vaccine, Candid No.1, has been used for decades to protect people at high risk. The reclassification means that even a modified, attenuated version of a vaccine can be deemed dangerous enough to require the highest level of biosecurity. This could make it harder and more expensive for researchers and public health officials to work with and distribute the vaccine, even for humanitarian purposes.