Boulder County Public Health and CU Boulder are working to align our COVID data reporting methodology as much as possible. Review the reporting diagram for more information about how data is reported and shared.
The Boulder County Public Health Epidemiology and Surveillance Teams currently use our own data system in addition to the state data system to ensure we are reporting on the most up-to-date information. Each week, the Surveillance Team compares the state data to the Boulder County data to check if case investigations or interviews found that someone who was categorized as a Boulder County resident actually lives in another Colorado county. If this occurs, that person’s record is deleted from the Boulder County data system which is reflected in the data immediately. The team also looks for duplicate records and merges the records if duplicates are identified. Lastly, a check is performed to ensure that we are capturing all deaths reported to the state among people with COVID-19. Although we receive death information directly from the coroner and patient medical records, there have been instances where a death was reported to the state only and we discovered it through our quality assurance process.
About this Information
Individuals (cases) are counted on the day in which they are reported to the state data system, regardless of the day the investigation was completed. There was one day – April 23, 2020 – in which a backlog of test results was received through this system.
Hospitalization information is determined during the first disease interview or through medical record review. Quality assurance processes may identify hospitalization after an interview occurred if medical record information can be located. We do not have access to information about who is no longer hospitalized with COVID-19.
COVID-19 death data represents the total number of deaths reported among people who have tested positive or considered probable for COVID-19, even when COVID-19 may not have been the cause of death listed on the death certificate. This information is required by the CDC and is crucial for public health surveillance, as it provides more information about disease transmission and can help identify risk factors among all deaths across populations.
Deaths are identified through medical record review, notification by the Boulder County coroner, notification by a long-term care facility or other healthcare provider, and through information from the Colorado Department of Public Health and Environment including death certificates.
Boulder County Public Health reports deaths of individuals with COVID-19 who are Boulder County residents. The Boulder County Coroner reports all deaths that occur within the county, regardless of county of residence.
As with all reportable diseases, Boulder County Public Health staff contact each Boulder County resident who tests positive for COVID-19 to identify any person who may have come in close contact with the ill person. Each close contact who is identified as at-risk of contracting the disease is then contacted and provided guidance for next steps, including isolation, quarantine, and/or testing, if needed.
These practices are vital to identifying the presence of disease and the response actions needed to protect residents.
It may be deemed that a person is “Probable” (e.g. clinically diagnosed for COVID-19 or epidemiologically linked) if they came in close contact with a person who has tested positive for COVID-19 and was determined to be high risk during the disease investigation, AND they became symptomatic in the two weeks after contact with the ill person or the two weeks before, while they were infectious. Probable cases are determined using the CDC and Council of State and Territorial Epidemiologists case definition which includes both epidemiological and clinical criteria.
Testing data includes every individual for whom we have received a positive result for a diagnostic (PCR) test. Every individual is only counted once, even if they have multiple positive tests.
Individuals who received a positive antibody test are NOT considered confirmed cases. These individuals could be considered a probable case if they also meet clinical or epidemiological criteria. This represents less than 1% of Boulder County cases.
Testing data includes all tests among people who report a Boulder County residence regardless of where testing was received. Not all labs historically reported negative lab results but most labs now report both positive and negative test results.
The percent positive is calculated by dividing all positive PCR tests among Boulder County residents by all PCR tests performed among Boulder County residents since COVID-19 testing began. The 5-day average is the proportion of all tests that were positive over the last 5 days with complete data (3 days prior to the current day).