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Northern Virginia is populous region of Virginia just outside of D.C. and includes the counties of Fairfax, Alexandria, Arlington, Loudoun, and Prince William. The population is about 2.36 million people, which accounts for almost 28% of the population of the state. This analysis focuses on the data related to the COVID-19 pandemic, specifically in Northern Virginia. The goal is to highlight trends in the region and discover insights.

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We use data from the Virginia Department of Health . The source data was downloaded from the Virginia Department of Health website and is as of September 29, 2022.

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Cases and Hospitalizations

These charts show the 5-day moving average for both reported cases and hospitalizations. At times these data points appear to drop below zero. This is due to corrections made in the source data. For example, on November 23, 2021, the cumulative number of hospitalizations in Fairfax County dropped by over 200 from the previous day and that causes the chart of the 5-day average of hospitalizations to dip well below zero.

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The following chart shows the 5-day average for the hospitalization rate in Northern Virginia since the start of the pandemic. The hospitalization rate is the ratio of hospitalizations to positive cases reported each day. In this chart, the rate is not allowed to drop below zero, due to the data quality adjustments artificially creating large dips in the hospitalization counts.

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COVID-19 Testing

The following charts explore the trends in PCR tests for COVID-19 in Northern Virginia. Again the data is from the Virginia Department of Health. The first chart shows the number of tests processed daily, smoothed with a 5-day moving average. The second chart shows the percent of tests that were positive for COVID-19 each day, again smoothed with a 5-day moving average. This information should be paired with the number of new cases in the chart above, as the number of tests is an important input into evaluating the trend in positive cases. As more people get tested, one would expect more positive cases to be returned.

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Active Cases and Hospitalizations

How many people in Northern Virginia currently have COVID-19? We use the term “Active” to refer to cases from the past 14 days. The duration of illness or infection from COVID-19 is up to 14 days, for most people. For a given day, the “Active Cases” metric is the total number of reported cases for the past 14 days. This allows us to focus on the current spread of the disease in Northern Virginia, vice cases that have long since resolved. It can also give you a sense of the likelihood of interacting with an individual with COVID-19.

For example, there were 5,239 active cases on September 29, 2022. This means in an area with a population of over 2.3 million, a total of 5,239 people were positive for COVID-19 on that day. Of course, this does not account for people who have COVID-19 but have not been tested, including a potentially substantial number of asymptomatic individuals.

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The active hospitalizations metric is similar in that it captures the total number of hospitalizations in the past 14 days for each day. Again, the data quality adjustments can cause artificial declines, even to zero, for short periods of time, as was the case around November 23, 2021.

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Cases By County

Not all counties in Northern Virginia are the same. This chart shows the 5-day moving average of cases by county in Northern Virginia.

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