PHOENIX (AP) — About 10% of Maricopa County residents have been infected with COVID-19 since the start of the pandemic, according to a new study released Monday.

The survey from the county’s Department of Public Health in partnership with Arizona State University and the Mayo Clinic estimated that about 470,000 people in the Phoenix metro area have contracted the coronavirus.

The 11-day study was conducted in mid-September and randomly selected 260 participants in 169 households from across the county to test for virus antibodies.

Meanwhile, Arizona health officials on Monday reported 1,476 new COVID-19 cases but no additional deaths.

The state Department of Health Services released its latest coronavirus figures as the number of COVID-19 hospitalizations, including ventilator use, continues to trend upward.

The total number of confirmed infections in Arizona since the pandemic started now stands at 276,912, with 6,302 deaths.

Cochise County currently has 595 active coronavirus cases, according to data provided on the county health department website. According to state data, 77 people in the county have died from the virus.

Nearly half of the active cases in the county are in the 85607 zip code, which includes Douglas, data shows. The two zip codes which comprise, 85635 and 86650, Sierra Vista have nearly 100 active cases between them.

The number of infections is thought to be far higher because many people have not been tested, and studies suggest people can be infected with the virus without feeling sick.

Arizona’s outbreak bottomed out in September but has steadily worsened through October and into November.

Health officials have said the recent surge is tied to factors including businesses and schools reopening and public fatigue with precautions such as mask-wearing.

Warning that conditions likely will get worse because of Thanksgiving gatherings and other socializing, officials advise people to avoid gathering with those outside their households. They also urge people to wear masks in public, practice social distancing, wash hands frequently and stay home when sick.

In other developments:

— Arizona Rep. Debbie Lesko’s office said Monday that she will quarantine for two weeks after recently coming into contact with someone who later tested positive for COVID-19. The Republican congresswoman said she is feeling no symptoms but will quarantine as a precaution. She will remain in her Peoria home instead of traveling to Washington, D.C., as planned.

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