26 July 2020 Blog Post: COVID-19 in Los Angeles County

Logging into Los Angeles County’s COVID-19 data portal, the first thing that you see is a bright yellow banner:

“DISCLAIMER: The lower number of cases are, in part, due to lab result reporting delays in the State electronic lab system. The number of cases is expected to increase in the coming days once the data becomes available. The hospitalization data is also incomplete due to changes in reporting requirements from the U.S. Department of Health and Human Services (HHS).”

Each day, Los Angeles County reports a total number of new cases and new deaths. What they don’t tell you is that those are old data. For instance, on 7/23/2020 they reported 2014 new cases and 49 deaths. Readers are left with the impression that that is the total number for that day. Instead, those are spread across many previous days – some perhaps as long as three weeks ago. The actual numbers (as of today) are 366 cases and 18 deaths. These will no doubt climb far higher as lab results trickle in – more likely over weeks than days.

The fact that we are experiencing reporting delays of this magnitude in late July is beyond infuriating. But moral outrage aside, it also leaves us with essentially useless data.

Below is the “current” epidemic curve for cases in Los Angeles County. A couple of patterns are clear:

1. The curve was essentially flat throughout the entire month of May.
2. At no point has there been a sustained downtrend in cases in Los Angeles, the sort that would be needed to support a rational reopening strategy.
3. On 6/12, Los Angeles County proceeded with lifting restrictions on indoor dining, bars and gyms in spite of the fact that cases had risen 12% and 26,7% in each of the two weeks prior.
4. Since 5/29, Los Angeles County has experienced a geometric rise in cases.
5. Data after 7/3 appear to be inaccurate and noisy as they just bounce around without a clear trajectory (Note that statewide closure of all indoor activities occurred 7/13)
6. The sharp drop reported for the week ending 7/24 is most certainly not a real effect but, rather, represents massive reporting delays.
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This graph gives me very little confidence in our County’s ability to accurately assess and respond to the ongoing COVID-19 surge. In June, the pattern was clear that cases were on the rise – yet the County pressed forward carelessly with reopening. Now we are faced with far less clear data, hampered by massive reporting delays (I would suspect they are still clearing data from the July 4th weekend). If the County makes poor decisions with good data, just imagine what they will do with bad data.

𝗦𝗢𝗴𝗻 𝗨𝗽 𝗳𝗼𝗿 π—’π˜‚π—Ώ π—‘π—²π˜„π˜€π—Ήπ—²π˜π˜π—²π—Ώ

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