This report contains information about how LA County and the City of LA performed yesterday, on a number of key COVID-19 indicators related to the speed at which opening up can occur. Taken together, performing well against the benchmarks provide confidence in moving through each phase of reopening.
LA is certainly an epicenter.
As long as LA consistently tests large portions of its population with fairly low positive COVID-19 results, sustains decreases in cases and deaths, has stable or decreasing COVID-related hospitalizations, and stocks ample available hospital equipment for a potential surge, we are positioned to continue loosening restrictions. When any one indicator fails to meet the benchmark, we should slow down to consider why that is happening. When multiple indicators fail to meet the benchmark, we should pause our reopening plans and even enact more stringent physical and social distancing protocols by moving back a phase.
Below, you will see how LA performed yesterday on the following indicators. The data does have a one day lag. Whenever City of LA (subset of LA County) data is available, it is also reported.
Related daily reports:
CA's Blueprint for a Safer Economy assigns each county to a tier based on case rate and test positivity rate. If counties fall into 2 different tiers on the two metrics, they are assigned to the more restrictive tier. Tiers, from most severe to least severe, categorizes coronavirus spread as widespread; substantial; moderate; or minimal. Counties must stay in the current tier for 3 consecutive weeks and metrics from the last 2 consecutive weeks must fall into less restrictive tier before moving into a less restrictive tier.
Case Rate per 100k: the unadjusted case rate per 100k. Any value above 7 is widespread; a value of 4-7 is substantial. CA does adjust the case rate based on testing volume, but that is not done here.
Test Positivity Rate: percent of tests that are COVID-positive. Any value above 8% is widespread; a value of 5-8% is substantial.
These indicators can fail to meet the lower benchmark; meet the lower benchmark; or exceed the higher benchmark.
Cases and deaths: the number of days with declining values from the prior day over the past 14 days. Guidelines state both should sustain a 14-day downward trajectory. Any value less than 14 means we failed to meet this benchmark.
Daily Testing: number of daily tests conducted for the county 2 days ago (accounting for a time lag in results reported). LA County's goal is to test 15,000 daily (45 tests per 1,000 residents) (lower bound). Chicago's goal was 50 tests per 1,000 residents, translating to 16,667 tests daily (upper bound). Below 15,000 (county) means we failed this benchmark.
Positive Tests: proportion of positive tests last week, values fall between 0 and 1. CA's positivity requirement is 8% or below (upper bound), but experts say that less than 4% is necessary to halt the spread of the virus (lower bound). More than 8% positive for the past week means we failed to meet this benchmark.
Positive Tests (WHO): proportion of positive tests in the past 2 weeks, values fall between 0 and 1. The weeks are weighted by the number of tests conducted. The WHO recommends that tests return less than 5% positive for 14 days prior to reopening. JHU has a state-by-state analysis of this. More than 5% positive over two weeks means we failed to meet this benchmark.
Hospitalizations: the 7-day averaged daily percent change in all COVID hospitalizations and COVID ICU hospitalizations; values fall between 0 and 1. CA guidelines ask for stable or downward trends, not exceeding a 5% daily change. Above 5% means we failed to meet this benchmark.
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CA Reopening Metrics: Los Angeles County
| Current Week | One Week Ago | Two Weeks Ago | |
|---|---|---|---|
| Overall Tier | 4 | 4 | 4 |
| Case Rate per 100k | 12.34 | 8.47 | 9.32 |
| Test Positivity Rate | - | - | - |
Indicators for LA County and City of LA
| LA County | |
|---|---|
| Cases | 5 |
| Deaths | 4 |
| Daily Testing | - |
| Positive Tests | 0.18 |
| Positive Tests (WHO) | 0.11 |
| COVID Hospitalizations | -0.01 |
| COVID ICU Hospitalizations | -0.04 |
| City of LA |
|---|
| 0 |
| 0 |
| - |
| - |
| - |
| - |
| - |
These are the trends in cases and deaths for the county and the city since 4/15/20, using a 7-day rolling average.
The cases and deaths requirement is that both have been decreasing for the past 14 days. The past 14 days are shaded in gray.
These charts show the amount of daily testing conducted and the percent of tests that came back positive for COVID-19 by week since 4/15/20.
LA County's goal is to conduct an average of 15,000 tests a day, a rate of 45 tests per 1,000 residents (lower bound). Chicago, another region faced with a severe outbreak, set the precedent for regional benchmarks being more stringent than statewide requirements if a particular region underwent a more severe outbreak. Chicago's goal is 50 tests per 1,000 residents, or 16,667 tests per day (upper bound).
The daily testing requirement is that we are conducting at least 15,000 tests daily until a vaccine is ready. We need to consistently record testing levels at or above the lower dashed line.
LA County's data, though subject to a time lag, does report the number of positive tests per testing batch. We aggregate the results by week. Only weeks with all 7 days of data available is used for the chart, which means the current week is excluded.
The chart compares the percent of positive test results, the number of positive cases, and the number of tests conducted. The percent of positive test results is the indicator of interest, but it is extremely dependent on the number of tests conducted. A higher percentage of positive tests can be due to more confirmed cases or fewer tests conducted. Therefore, the next chart shows the number of tests conducted each week (blue) and the number of positive tests (gray). It also shows the testing upper and lower bounds, which is simply the daily testing upper and lower bounds multiplied by 7.
How to Interpret Results
CA's weekly COVID-19 positive share requirement is that tests coming back positive is 8% or below (upper bound), but experts say that less than 4% positive is necessary to halt the spread of the virus (lower bound).
Caveat 1: Testing data for city only counts tests done at city sites. Oral swabs are used by county/city sites, which have an approximate 10% false negative rate. On average, 10% of negative tests are falsely identified to be negative when they are actually positive. At the county level, we do have information on total number of tests, which include county/city sites and private healthcare providers (anyone who provides electronic data reporting), such as Kaiser Permanente. We use the Tests by Date table. There is a time lag in results reported, and we are not sure if this lag is 3, 5, or 7 days for the results from an entire testing batch to come back.
Caveat 2: The situation on-the-ground is important for contextualizing the data's interpretation. When testing capacity is stretched and testing is rationed, those who are able to obtain tests are more likely to test positive. This distorts the share of positive results, and we expect the positivity rate to increase when we target the riskiest subgroups. We are excluding a subset of cases that would test positive, if testing supplies were available. Factoring in the high false negative rate from oral swabs used at county/city sites, we are undercounting the actual number of cases, but are observing trends from the riskiest or most vulnerable subgroups.
Data on all COVID-related hospitalizations and ICU hospitalizations comes from the CA open data portal made available 6/25/20; this data covers the entire county. These charts show the number of hospitalizations from all COVID cases and also ICU hospitalizations for severe COVID cases.
CA guidelines state that hospitalizations should be stable or downtrending on 7-day average of daily percent change of less than 5%. LA County's all COVID-related hospitalizations and COVID-related ICU hospitalizations (subset of all hospitalizations) are shown.
If you have any questions, please email ITAData@lacity.org.