Current data quality grade
To help the public understand how well each state is performing, we have assigned each state a data-quality grade based on our assessment of the completeness of their reporting. Learn more
Prior to April 1, 2020, we used county data sources for more reliably timely reporting of California's COVID-19 data. At the start of April, we began reporting primarily from the state data dashboard(s). This led to a modest drop in cases and deaths, as the state's data lags behind the county sources.
On April 4 and April 22, 2020, California reported large batches of backlogged negative test data.
As of April 22, 2020, California has reported specimens tested instead of people tested. Because some people may be tested more than once, this number is probably higher than the number of people tested.
On July 8, 2020, California data included a backlog from Los Angeles County, which had not reported for several days. Approximately 1,000 of the 11,000 new cases were attributed to this backlog data.
From June 29 to July 5, 2020, California made revisions to daily case numbers. On July 17, we updated the values based on the most recent data from the state dashboard.
From July 23 through July 28, 2020, California reported that its Now hospitalized and Now in ICU were incomplete due to its transition to the HHS reporting system. We carried over hospitalization figures until July 28. We will backfill the complete numbers for this period if the complete data becomes available.
As of September 18, 2020, California's total test results are drawn from our
totalTestsViral field instead of calculated via positive+negative.
Negative test results reported in our API and CSVs are calculated by subtracting Positive PCR tests (people) from Total PCR tests (specimens) in the absence of better data.
New tests (Calculated)Total PCR tests (specimens)
New cases (Calculated)
New deaths (Calculated)
We calculate daily changes based on the data states report each day. Some states report new cases, tests, and deaths using other methods. Please consult official state data sources for more information. We chart “New tests” using different units across jurisdictions, because not all states and territories report tests in the same units. Learn more about total test units and see what we chart for each jurisdiction in our total tests documentation.
We do not have a complete dataset for every metric in every state. If we we have data for less than 30% of the past 90 days for a given metric, you’ll see a warning instead of a chart for that metric.
All the data for these charts is available for download. You can also review tabular national data on our US historical data page and data for each state and territory on the individual state or territory’s overview page.
Viral (PCR) testsHistorical data for viral (PCR) tests
(in test encounters)