On June 1, 2020, Massachusetts began to report probable cases and probable deaths*, causing Total cases and Total deaths** to appear to increase sharply in our data.
On June 30, 2020, Massachusetts decreased the number of cumulative hospitalizations and confirmed and probable deaths "due to ongoing data cleaning which identifies and removes duplicate reports."
On July 31, 2020, Massachusetts noted that "Delays in the reporting of test results to DPH from multiple laboratories, including large national commercial laboratories, are reflected in today’s case counts. However, these positive test results have been assigned retrospectively to the appropriate date of test." We will backfill case data for Massachusetts in the near future.
On August 12, 2020, Massachusetts began reporting probable cases weekly instead of daily. This can lead to apparent spikes in the data when the weekly numbers are incorporated, as happened on August 19. Beginning August 20, 2020, we will use the daily total case count from the race and ethnicity section of the dashboard, which includes both confirmed and probable cases, and will backfill the previous week's case counts.
On August 31, 2020 we updated Massachusetts' Total PCR Tests (specimens) before August 12, 2020 based on the state's "Tests by Date" dataset, extending the column back to January 22, 2020.
On September 2, 2020, MA reported that it had shifted to using the more restrictive August 6 definition of probable cases released by the CSTE. This change caused a significant decrease in several data points where probable cases or probable deaths were included, particularly the overall case count, which dropped by more than 7,000. Historical data was also affected.
As of September 11, 2020, Massachusetts’ total test results reflect total specimens. The number of unique people tested is available in our API as
Negative test results reported in our API and CSVs are calculated by subtracting Positive PCR tests (people) from Total PCR tests (people).