COVID-19 Surveillance Dashboard: Data Dictionary & FAQs

These FAQs and data dictionary terms relate to the COVID-19 surveillance dashboard

FAQs:

1. Why do the number of positive COVID-19 cases change on past dates?

The data sources we use are dynamic, which means they are routinely updated. Marin County Public Health receives reports of positive COVID-19 cases thru CalREDIE, the state’s electronic lab reporting (ELR) system.  There are significant delays in CalREDIE reporting (approximately 4-7 days) especially from private labs. Labs are processing high volumes of tests daily and are not reporting same-day results. There are also delays due to the need for  manual entry of faxed laboratory results. Data is updated daily as CalREDIE information is updated.  Cases can be reassigned to the county of residence or have status changed from suspected to confirmed, which results in a change of case counts.  

2. Why does the daily increase in the cumulative case count not always align with the daily positive cases reported?

You may notice that the number of new cases from day to day does not match the cumulative total of cases reported. Marin County Public Health has implemented quality control measures to ensure accuracy. For example epidemiologists de-duplicate data, including repeat tests, multiple reports, and corrected residency status (e.g., corrected home address). All official case counts for COVID-19 are based on county of residence.

The daily cumulative case count reflects new cases that were reported to Marin County Public Health since yesterday. New cases reported to us on a given day may have been tested at an earlier date. In comparison,  the daily positive cases chart shows the number of cases identified by date someone was tested for COVID-19.  This date estimates the day symptoms began, which helps us understand the timing of the spread of the virus in our community. Click here to watch a video of one Marin County's Epidemiologists explaining the difference between testing date and report date.

3. Why are the number of negative tests so low for the most recent 4-7 days?

While there are reporting delays (see question 1 & 2), reporting positive test results are prioritized by labs to assist in contact tracing and case investigation. Therefore positive test results are often reported sooner than negative test results. In many cases, negative tests results are reported into CalREDIE via electronic lab reporting, which may be delayed due to a high volume of tests.

4. Why is some data on the website for residents only and other data is for a broader population?

For some factors, we want to understand our county’s service capacity and needs.  For example, we test non-residents who work in Marin County providing essential services (e.g., work as care providers in nursing homes or are first responders).  For other measures, such as the number of cases in our community, we only look among Marin residents as it helps us understand how those who live in Marin County are impacted by this disease.

5. Why are COVID-19 cases, hospitalizations and deaths from San Quentin State Prison reported separately from the total case count for Marin County?

COVID-19 cases occurring in the community have different implications for community spread and health department contact tracing and investigation compared to cases occurring in San Quentin State Prison. Including cases that occur in San Quentin State Prison in our overall case counts may mask our ability to identify significant trends in community transmission. Tracking both indicators is important for understanding COVID-19 impacts among all of our community members, including hospital capacity, and to appropriately tailor prevention, outreach, and treatment to each setting. COVID-19 cases occurring in San Quentin State Prison are formally under the jurisdiction of the State of California and the California Department of Corrections. Marin County supports and collaborates with San Quentin State Prison during outbreak responses at their request. For up to date information on COVID-19 in state run correctional facilities please visit the CDCR Population COVID-19 Tracking Report.

Cumulative hospitalizations of San Quentin State Prison inmates hospitalized for COVID-19 at MarinHealth, Kaiser Hospital or Novato hospital will be counted separately from cumulative hospitalizations of Marin residents living in the community.  Tracking the indicators separately allows for a greater understanding of COVID-19 impacts among all our community members.  Daily hospital census counts include both community and San Quentin cases as it is a measure of hospital capacity. Daily hospitalization census data is primarily used to monitor impacts of COVID-19 on hospital capacity, whereas cumulative hospitalizations overtime help us under the community impacts as a result of COVID-19.

Deaths resulting from COVID-19 at San Quentin will also not be included in the cumulative total death count for Marin residents.

6. Why do increases in the daily hospital census (“Current COVID-19 hospitalizations”) not always align with daily increases in the total cumulative hospitalization/newly reported hospitalizations?

There are a few reasons why increases in the daily hospital COVID-19 census will not line up every day with the increases in cumulative hospitalizations:

  • These are two different measurements coming from two different sources– total/cumulative hospitalizations are calculated using Marin HHS’ contact investigation database to determine cases of Marin County residents who have been hospitalized with COVID-19. The “Current COVID-19 hospitalizations” and hospital census & ICU chart come from a daily poll conducted by California Department of Public Health (CDPH) where hospitals provide the count of COVID-19 patients in their hospital on that day. Daily hospitalization census data is primarily used to monitor impacts of COVID-19 on hospital capacity, whereas cumulative hospitalizations overtime help us under the community impacts as a result of COVID-19.
  • Reporting delay-  if someone enters the hospital on 6/15 it may take 2-3 days for that hospitalization to be reported to Marin HHS and entered into Marin HHS’ contact investigation database. For example, if the daily hospitalization census jumps from 2 to 6 people from 6/8 to 6/9 it may not be reflected in the count of total hospitalizations until 6/12.
  • Resident status – Finally, not all people hospitalized in Marin County hospitals will be counted as hospitalizations among Marin County residents. CDPH daily census data can include out of county residents that are not counted in our cumulative hospitalizations (this is Marin County residents only). For example, if someone who lives outside of Marin County was hospitalized at MarinHealth, Novato or Sutter they would be captured in the CDPH census (helping us understand hospital capacity), but not counted in cumulative hospitalization (helps us understand severity of COVID-19 spread in Marin County). Likewise, if a Marin resident was hospitalized in another county, that hospitalization would be counted towards the total hospitalizations but would not be reflected in the daily census.
  • Quality Assurance –  MarinHHS actively engages in QI efforts to ensure COVID-19 data is being accurately reported to the public. On occasion this may mean that data needs to be updated to reflect new guidance or to address any data entry errors.

Data Dictionary

 Today's Updates:

Variable Definition
Newly reported cases New cases represent newly identified cases since yesterday’s reporting (Marin County residents only, does not include San Quentin inmates)
Newly reported hospitalizations New hospitalizations represent identified cases that have been newly identified as being hospitalized. It reflects if there has been a change in the count of total hospitalized cases from the previous day. It only includes Marin County residents and does not include San Quentin inmates.
Current COVID-19 hospitalizations These are the number of COVID-19 positive patients currently in MarinHealth, Novato and Sutter hospitals (does not include Kentfield hospital). This includes residents and non-residents with a confirmed COVID-19 diagnosis (excludes suspected cases) in the hospital (does not exclude San Quentin inmates).
Newly reported deaths Newly reported deaths represent the number of newly reported deaths from COVID-19 since yesterday (Marin County residents only, does not include San Quentin inmates).

 Cumulative Information:

Variable Definition
Total Cases  

Total cases reported to the Marin County Health Department since March 4, 2020 (Marin County residents only, does not include San Quentin inmates).

Total Recovered  

Total confirmed COVID-19 cases who are 14 days post-diagnosis with COVID-19 (based on test date) excluding deaths and those currently hospitalized (Marin County residents only, does not include San Quentin inmates).

Total Hospitalized  

Total number of Marin County residents hospitalized for COVID-19 (does not include San Quentin inmates)

Total Deaths  

Total number of confirmed COVID-19 deaths reported to the Marin County Public Health (Marin County residents only, does not include San Quentin inmates).

Total Persons Tested

This includes the total number of Marin County residents tested based on information from CalREDIE and the total number of individuals tested by labs within Marin County that do not report to CalREDIE.

San Quentin Table

Variable Definition
Active Cases  

This comes from the California Department of Corrections and Rehabilitation COVID-19 patient dashboard.

Daily Trends:

Variable Definition
Daily count of positive results and total tests for Marin County residents CalREDIE data only, only for Marin County residents, uses specimen collection date. Data for the most recent 4-7 days may be delayed due to reporting and testing delays.
Daily COVID-19 Tests Conducted An estimate of the total number of tests conducted in Marin County.  Based on the number of tests conducted by or reported directly to Marin County Public Health plus an estimated number of tests expected from labs who are delayed in reporting or fail to report to CalREDIE based on historic averages. Counts include all individuals tested in Marin, including non-residents and residents.
Daily Hospital and ICU COVID-19 Cases Census of daily and ICU hospitalization, includes residents and non-residents. ICU cases are a subset of the total daily census of confirmed COVID-19 cases. Does not include patients at Kentfield hospital. Does not exclude COVID-19 San Quentin inmates if they are hospitalized at MarinHealth, Kaiser or Novato hospitals.

Weekly Count of All-Cause Deaths in Marin County

Number of deaths from any cause reported to Marin County Public Health (Marin County residents only).