April 20th Data Update

This post updates COVID-19 confirmed case data for the DC Metropolitan area as of April 20th 2020. The total confirmed cases in the DC area rose by 882 to 14,685, from the previous total of 12,987, an approximate 6% increase. The doubling time (3-day moving average) for cases in the DC area is approximately 11.1 days. 

Fatalities rose by 43 to 494, from the previous total of 451, an approximate 10% increase. The doubling time (3-day moving average) for fatalities in the DC area is approximately 7.9 days.
Cases
DC Region: 14,685
By State
DC Region (14,685)
Maryland: 7,238
District of Columbia: 3,098
Virginia: 4,349

By Jurisdiction
Maryland (7,238)
Frederick County: 616
Montgomery County: 2,647
Prince George's County: 3,583
Charles County: 392

District of Columbia (3,098)

Virginia (4,349)
Arlington County: 593
City of Alexandria: 421
Fairfax County: 1,970
Loudoun County: 446
Prince William County: 919




Fatalities
DC Region: 494
By State
DC Region (494)
Maryland: 268
District of Columbia: 112
Virginia: 114

By Jurisdiction
Maryland (268)
Frederick County: 30
Montgomery County: 106
Prince George's County: 112
Charles County: 20
District of Columbia (112)

Virginia (114)
Arlington County: 22
City of Alexandria: 8
Fairfax County: 59
Loudoun County: 8
Prince William County: 17


Comments

  1. UnknownApril 21, 2020 at 8:16 AM

    A little confused here. So the 6% and 10% growth, is that a good thing? Is that the tendency we need to have to say we are off the peak or in the "plateau" moment? Thanks for your info.

    ReplyDelete
    Replies
    1. TYApril 21, 2020 at 8:24 AM

      I'm not sure what the ideal growth rates are. My next bit of analysis was going to try to calculate an R0 figure. I do know that doubling times in the double digits is generally seen as a good sign.

      Regarding peak vs plateau, it really takes hindsight to make the call. Left unsaid with my numbers is testing capacity. I don't address that issue because I don't have the time or desire to do so, but it may be the regional testing capacity has hit its limit, and that there are more than the ~800 cases that we've seen for the last few days, and that they're just going untested.

      I was going to revisit my assessment of the peak around the turn of the month, to see how that assessment has corresponded with the data from the rest of April.

      Thanks for your comment, and appreciate the readership.

      Delete
  2. Captain Sea LevelApril 21, 2020 at 9:20 AM

    The percentage growth rate is not that useful, especially if you are measuring total cases. Hospitalization is a better indicator. For cases, its more useful to track the daily count of new cases to see where that is stabilizing and where it is still increasing--maybe as a 5-day running mean. Statewide, Maryland hit a plateau about a week ago. PG seems to be peaking about now, in terms of daily new cases. The total of active cases will hit a peak about 10 days after daily cases.

    I'm a bit confused about where the zip code data are for DC and VA. Maryland puts up a different zip code map each day. Counties are a bit large for tracking what is going on. Where are the DC and VA zip code data sets published?

    ReplyDelete
    Replies
    1. TYApril 21, 2020 at 10:21 AM

      Your suggestions sound like a promising data set. If you send me a link to your analysis, I'll be sure to incorporate/cite as I use it.

      Delete
    2. Captain Sea LevelApril 21, 2020 at 12:22 PM

      https://coronavirus.maryland.gov/ has most of what I am talking about. I love the zip code maps. I've been taking note of the data points that interest me every day, since they do not republish a time series of everything that they report every day. They do publish their time series of daily new cases.

      But any idea where the VA and DC zip codes are published?

      Delete
    3. TYApril 21, 2020 at 1:49 PM

      I have no idea. I recognize the value of zip-code level analysis, particularly in larger jurisdictions such as Fairfax County which have large populations and geographic areas. However, this blog is a personal hobby of mine while I'm in a WFH status; I simply don't have the time or desire to get that granular in my work.

      Delete
  3. MongooseApril 21, 2020 at 1:41 PM

    In terms of what is the "peak" I'd go by absolute daily case increase rather than percentage increase. I think as long as the number of new cases per day is accelerating (800, 850, 880, etc.) , you can't really say we've hit a peak. As long as new case count is accelerating, we'll eventually run out of hospital capacity. We don't know how many daily hospital discharges there are but to avoid breaching capacity, we eventually need for new cases to be less than or equal to discharges (zero net new hospitalizations).

    ReplyDelete
    Replies
    1. TYApril 21, 2020 at 1:50 PM

      I am planning on revisiting my assessment of the peak around the start of May. It's quite possible that the total count of new cases is maxing-out on account of limited testing capacity, but that something I'm not ready to address at this point.

      Delete

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