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Cases of COVID-19 are on the rise in the U.S., with the surge even more apparent in the latest data from the Centers for Disease Control and Prevention.

As of Thursday, all but 19 U.S. counties are experiencing high community transmission of COVID-19. A high transmission rate means a county has reported 100 or more new cases of COVID-19 per 100,000 people in the past seven days, or has 10% or more positive Nucleic Acid Amplification Tests (NAATs) during the same time frame.

Currently, more than 99% of the U.S. has met or exceeded that threshold. That includes all of California’s 58 counties, as seen in the CDC map below.

California’s level of community transmission of COVID-19 as of Jan. 13, 2021. (Centers for Disease Control and Prevention)

The CDC’s latest data shows California has reported over 735,000 new cases of COVID-19 over the last seven days. That equates to roughly 1,863 new cases per 100,000 persons. Counties seeing the highest case rates over the last seven days include Los Angeles, San Diego and Inyo.

Under the CDC’s guidelines, a county can only move from high community transmission down to substantial community transmission when new cases per 100,000 over the past seven days drop between 50 and 99.99, or the percentage of positive test results in the same period is between 8% and 9.99%.

The county closest to reaching that threshold is Trinity County, which has a case rate of of 203.50 per 100,000 people over seven days.

The CDC recommends everyone living in counties marked with high or substantial community transmission of COVID-19 wear a mask while in public, indoor settings. Earlier this month, California’s indoor mask mandate was extended one month, through at least Feb. 15, amid surging cases of the omicron variant of the coronavirus.