It was established that the virus was a combination of human, North American swine, and Eurasian swine influenza viruses; the viruses from the initial two Californian cases were also noted to be resistant to amantadine and rimantadine, two common influenza antiviral drugs.[132] No contact with pigs was found for any of the seven Californian nor either of the two Texas cases, suggesting human-to-human transmission of the virus.