United States COVID-19 County Level of Community Transmission Historical Changes - ARCHIVED

On October 20, 2022, CDC began retrieving aggregate case and death data from jurisdictional and state partners weekly instead of daily. This dataset contains archived historical community transmission and related data elements by county. Although these data will continue to be publicly available, this dataset has not been updated since October 20, 2022. An archived dataset containing weekly historical community transmission data by county can also be found here: <a href="https://data.cdc.gov/Public-Health-Surveillance/Weekly-COVID-19-County-Level-of-Community-Transmis/jgk8-6dpn">Weekly COVID-19 County Level of Community Transmission Historical Changes | Data | Centers for Disease Control and Prevention (cdc.gov)</a>.

<b>Related data</b>
CDC has been providing the public with two versions of COVID-19 county-level community transmission level data: this historical dataset with the daily county-level transmission data from January 22, 2020, and a dataset with the daily values as originally posted on the COVID Data Tracker. Similar to this dataset, the <a href="https://data.cdc.gov/Public-Health-Surveillance/United-States-COVID-19-County-Level-of-Community-T/nra9-vzzn">original dataset</a> with daily data as posted is archived on 10/20/2022. It will continue to be publicly available but will no longer be updated. A new dataset containing community transmission data by county as originally posted is now published weekly and can be found at: <a href="https://data.cdc.gov/dataset/Weekly-COVID-19-County-Level-of-Community-Transmis/dt66-w6m6">Weekly COVID-19 County Level of Community Transmission as Originally Posted | Data | Centers for Disease Control and Prevention (cdc.gov)</a>.

This public use dataset has 7 data elements reflecting historical data for community transmission levels for all available counties and jurisdictions. It contains historical data for the county level of community transmission and includes updated data submitted by states and jurisdictions. Each day, the dataset was updated to include the most recent days’ data and incorporate any historical changes made by jurisdictions. This dataset includes data since January 22, 2020. Transmission level is set to low, moderate, substantial, or high using the calculation rules below.

<b>Methods for calculating county level of community transmission indicator</b>
The County Level of Community Transmission indicator uses two metrics: (1) total new COVID-19 cases per 100,000 persons in the last 7 days and (2) percentage of positive SARS-CoV-2 diagnostic nucleic acid amplification tests (NAAT) in the last 7 days. For each of these metrics, CDC classifies transmission values as low, moderate, substantial, or high (below and <a href="https://www.cdc.gov/mmwr/volumes/70/wr/mm7030e2.htm?s_cid=mm7030e2_w#T1_down">here</a>). If the values for each of these two metrics differ (e.g., one indicates moderate and the other low), then the higher of the two should be used for decision-making.

<b>CDC core metrics of and thresholds for community transmission levels of SARS-CoV-2</b>

<b>Total New Case Rate Metric:</b> "New cases per 100,000 persons in the past 7 days" is calculated by adding the number of new cases in the county (or other administrative level) in the last 7 days divided by the population in the county (or other administrative level) and multiplying by 100,000. "New cases per 100,000 persons in the past 7 days" is considered to have transmission level of Low (0-9.99); Moderate (10.00-49.99); Substantial (50.00-99.99); and High (greater than or equal to 100.00).

<b>Test Percent Positivity Metric:</b> "Percentage of positive NAAT in the past 7 days" is calculated by dividing the number of positive tests in the county (or other administrative level) during the last 7 days by the total number of tests resulted over the last 7 days. "Percentage of positive NAAT in the past 7 days" is considered to have transmission level of Low (less than 5.00); Moderate (5.00-7.99); Substantial (8.00-9.99); and High (greater than or equal to 10.00).

If the two metrics suggest different transmission levels, the higher level is selected. If one metric is missing, the other metric is used for the indicator.

The reported transmission categories include:

Low Transmission Threshold: Counties with fewer than 10 total cases per 100,000 population in the past 7 days, and a NAAT percent test positivity in the past 7 days below 5%;

Moderate Transmission Threshold: Counties with 10-49 total cases per 100,000 population in the past 7 days or a NAAT test percent positivity in the past 7 days of 5.0-7.99%;

Substantial Transmission Threshold: Counties with 50-99 total cases per 100,000 population in the past 7 days or a NAAT test percent positivity in the past 7 days of 8.0-9.99%;

High Transmission Threshold: Counties with 100 or more total cases per 100,000 population in the past 7 days or a NAAT test percent positivity in the past 7 days of 10.0% or greater.

Blank: total new cases in the past 7 days are not reported (county data known to be unavailable) and the percentage of positive NAATs tests during the past 7 days (blank) are not reported.

<b>Data Suppression</b>
To prevent the release of data that could be used to identify people, data cells are suppressed for low frequency. When the <b>case counts</b> used to calculate the total new case rate metric ("cases_per_100K_7_day_count_change") is greater than zero and less than 10, this metric is set to "suppressed" to protect individual privacy. If the case count is 0, the total new case rate metric is still displayed.

The data in this dataset are considered provisional by CDC and are subject to change until the data are reconciled and verified with the state and territorial data providers. This datasets are created using <a href="https://www.cdc.gov/maso/policy/policy385.pdf">CDC’s Policy on Public Health Research and Nonresearch Data Management and Access</a>.

<b>Duplicate Records Issue</b>
A bug was found on 12/28/2021 that caused many records in the dataset to be duplicated. This issue was resolved on 01/06/2022.

于2022年10月20日，疾病控制与预防中心（CDC）开始每周从地方和州级合作伙伴处收集汇总的病例和死亡数据，而非每日收集。本数据集包含按县划分的历史社区传播及相关数据元素存档。尽管这些数据将继续对外公开，但自2022年10月20日起，本数据集已不再更新。您还可以在此找到按县划分的每周历史社区传播数据存档：[每周COVID-19县社区传播历史变化](https://data.cdc.gov/Public-Health-Surveillance/Weekly-COVID-19-County-Level-of-Community-Transmis/jgk8-6dpn)。

<b>相关数据</b>
CDC已向公众提供两种版本的COVID-19县社区传播水平数据：此历史数据集包含自2020年1月22日起的每日县社区传播数据，以及最初在COVID数据追踪器上发布的每日数据集。类似于本数据集，最初以每日数据形式发布的[原始数据集](https://data.cdc.gov/Public-Health-Surveillance/United-States-COVID-19-County-Level-of-Community-T/nra9-vzzn)也已存档于2022年10月20日。它将继续对外公开，但将不再更新。现在已发布一个包含最初发布的按县社区传播数据的每周新数据集，可在此找到：[每周COVID-19县社区传播原始数据](https://data.cdc.gov/dataset/Weekly-COVID-19-County-Level-of-Community-Transmis/dt66-w6m6)。

本公共用途数据集包含7个数据元素，反映了所有可用县和地区的社区传播水平历史数据。它包含县社区传播水平的历史数据，并包括州和地区提交的更新数据。每天，数据集都会更新以包括最新的数据，并纳入地区所做的任何历史变更。本数据集包含自2020年1月22日以来的数据。传播水平根据以下计算规则设置为低、中、高或极高。

<b>计算县社区传播指标的方法</b>
县社区传播指标使用两个指标：（1）过去7天内每10万人中的总新增COVID-19病例数；（2）过去7天内阳性SARS-CoV-2诊断核酸扩增测试（NAAT）的百分比。对于这两个指标，CDC将传播值分类为低、中、高（低于<a href=