View Comments Arizona health officials say there is, "definitely an uptick" in COVID-19 cases across the state, likely due to the highly contagious delta variant. Both vaccinated and unvaccinated Arizonans should care about the increase in cases because more transmission of the virus raises the likelihood of so-called "breakthrough" cases, Dr. Cara Christ, the Arizona Department of Health Services director, said this week. A breakthrough case occurs when someone becomes infected with the SARS-CoV-2 virus, or new coronavirus, that causes COVID-19, even though vaccinated. Such cases are rare, but they do happen. As of Monday, Arizona had recorded 3,540 breakthrough COVID-19 cases out of more than 3.2 million fully vaccinated people, Steve Elliott, a state health department spokesperson, wrote in an email. Twenty-eight of those vaccinated people are known to have died from COVID-19, Elliott said.