Tests were difficult to come by across the nation, after the Centers for Disease Control and Prevention (CDC) had botched the rollout of diagnostic kits and delayed allowing private and academic labs to develop their own. Initially, only the most severely ill patients were being tested, and those who had recently travelled were prioritized.It was only by looking back that California officials realized that the virus may have been spreading through the state and killing residents earlier than they had thought and it is speculated that the virus originated in Europe rather than China.