In S2E8 of Supergirl, Cyborg Superman deployed an aerosol weapon in a bar, which caused all of the alien patrons to die while all of the human patrons were unharmed.
Supergirl learned from a hologram of her father at the Fortress of Solitude that the weapon was the Medusa virus:
Medusa, a weaponized virus that I created for the defense of the planet Krypton. It was a joint partnership between the Science and Military Guilds. We bio-engineered the virus to attack non-Kryptonian physiology. In the event of an invasion, Medusa could be deployed to kill alien combatants while keeping our civilians and infrastructure safe from harm.
Supergirl later explained to the DEO:
Henshaw stole the virus's formula from the Fortress of Solitude, which means Cadmus can make as much of the virus as they want. An unstoppable bio-weapon that kills every alien except Kryptonians.
Later in the episode, right before the weapon was to be deployed on a wide scale, Cadmus broadcast a message indicating that the virus would kill all aliens except humans:
Tonight, every alien who has stepped foot on our planet will die. Because Earth is for the humans. The future is for the humans.
But if the virus attacks all non-Kryptonians, then shouldn't it kill humans too?