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The COVID Tracking Project will stop collecting data on March 7, 2021.

Massachusetts Overview

Data Reporting Assessment (Learn more about data quality assessments)

Last updated

When Massachusetts reports no data, several days of data, or unusual data (such as decreases in values that should increase), our volunteers note it here on the date the anomaly occurred. We also note here changes in our own methodology that affect the data.

Negative test results reported in our API and CSVs are calculated by subtracting Confirmed cases from Total PCR tests (people).

On December 25, 2020, Massachusetts announced on their COVID-19 page that there would be no update to their data on December 25, 2020, or on January 1, 2021. Additionally, they noted that data reported on December 26, 2020 and January 2, 2021 would each include two days of data.

On November 26, 2020, Massachusetts announced on their COVID-19 page that there would be no update to their data on November 26, 2020 due to the the Thanksgiving holiday. Additionally, they announced that the data for November 27, 2020 would include both the data for November 26, 2020 and November 27, 2020.

On November 25, 2020, Massachusetts reported that their data “was delayed today due to a technological issue that resulted in an interruption of the data download. As a result, today’s numbers reflect case counts from up to a 30 hour period" instead of the usual previous 24-hour period.

As of November 2, 2020, Massachusetts’ Currently Hospitalized, Currently in ICU, and Currently on Ventilator figures include only confirmed cases. Previously these numbers included confirmed and probable hospitalizations.

As of September 11, 2020, Massachusetts’ total test results reflect total specimens. The number of unique people tested is available in our API as totalTestsPeopleViral.

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.

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 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 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 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 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.