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.

自2022年10月20日起，美国疾病控制与预防中心（CDC）开始每周从辖区和州合作伙伴处收集汇总的病例和死亡数据，而非每日收集。本数据集包含了按县划分的历史社区传播及相关数据元素。尽管这些数据将继续公开提供，但自2022年10月20日起，本数据集未再更新。此外，您还可以在此找到包含按县划分的每周历史社区传播数据的存档数据集：<a href="https://data.cdc.gov/Public-Health-Surveillance/Weekly-COVID-19-County-Level-of-Community-Transmis/jgk8-6dpn">每周COVID-19县社区传播历史变化 | 数据 | 美国疾病控制与预防中心（cdc.gov）</a>。

相关数据

CDC向公众提供了两种版本的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，以及一个包含原始发布的每日值的COVID Data Tracker数据集。与该数据集类似，包含每日数据的原始数据集也于2022年10月20日存档，并将继续公开提供，但将不再更新。现在，一个新的数据集以每周频率发布，包含原始发布的按县划分的社区传播数据，可在以下网址找到：<a href="https://data.cdc.gov/dataset/Weekly-COVID-19-County-Level-of-Community-Transmis/dt66-w6m6">每周COVID-19县社区传播原始发布数据 | 数据 | 美国疾病控制与预防中心（cdc.gov）</a>。

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辖区社区传播水平的历时数据。它包含县社区传播水平的历时数据，并包括州和辖区提交的更新数据。每天，数据集都会更新以包含最新几天数据，并纳入辖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。

计算县社区传播指标的方法
县社区传播指标使用两个指标：(1)过去7天每10万人中的新增COVID-19病例总数；(2)过去7天SARS-CoV-2诊断性核酸扩增测试（NAAT）阳性率。对于这两个指标中的每一个，CDC将传播值分类为低、中、高（以下和<a href="https://www.cdc.gov/mmwr/volumes/70/wr/mm7030e2.htm?s_cid=mm7030e2_w#T1_down">以下</a>）。如果这两个指标中的值不同（例如，一个表示中，另一个表示低），则应使用两个值中较高的一个进行决策。

SARS-CoV-2社区传播水平的CDC核心指标和阈值

<b>总新增病例率指标：</b>“过去7天每10万人中的新增病例数”是通过将县（或其他行政级别）在过去7天内新增的病例数除以县（或其他行政级别）的人口数，然后乘以100,000来计算的。“过去7天每10万人中的新增病例数”被视为传播水平为低（0-9.99）；中（10.00-49.99）；高（50.00-99.99）；和极高（大于或等于100.00）。

<b>检测阳性率指标：</b>“过去7天NAAT阳性率”是通过将县（或其他行政级别）在过去7天内进行的阳性测试数除以过去7天内进行的总测试数来计算的。“过去7天NAAT阳性率”被视为传播水平为低（低于5.00）；中（5.00-7.99）；高（8.00-9.99）；和极高（大于或等于10.00）。如果两个指标建议的传播水平不同，则选择较高的水平。如果其中一个指标缺失，则使用另一个指标作为指标。

报告的传播类别包括：
低传播阈值：过去7天内每10万人中总病例数少于10例，且过去7天内NAAT阳性率低于5%；
中传播阈值：过去7天内每10万人中总病例数为10-49例，或NAAT测试阳性率为5.0-7.99%；
高传播阈值：过去7天内每10万人中总病例数为50-99例，或NAAT测试阳性率为8.0-9.99%；
极高传播阈值：过去7天内每10万人中总病例数为100例或更多，或NAAT测试阳性率为10.0%或更高。
空白：过去7天内未报告新增总病例数（已知县数据不可用），且过去7天内NAAT阳性率（空白）未报告。

数据抑制
为了防止发布可用于识别个人的数据，对低频率数据单元格进行了抑制。当用于计算总新增病例率指标（“cases_per_100K_7_day_count_change”）的病例数大于零且小于10时，此指标被设置为“抑制”，以保护个人隐私。如果病例数为0，则总新增病例率指标仍会显示。

本数据集的数据被视为CDC的临时数据，并可能发生变化，直到与州和领土数据提供者核对并验证数据为止。本数据集的创建遵循<a href="https://www.cdc.gov/maso/policy/policy385.pdf">CDC公共卫生研究和非研究数据管理和访问政策</a>。

重复记录问题
2021年12月28日发现了一个错误，导致数据集中许多记录被重复。该问题已于2022年1月6日解决。