In response to the COVID-19 pandemic, multiple testing options were made available to meet the needs of the City’s diverse population.

The initial Phase 1 COVID-19 testing strategy for the COH were supported by two key concepts – access and equity. “Access zip codes” and “equity zip codes” were established to help create the final priority zip codes.

The Phase 1 strategy had two primary goals: 1) establish a minimum baseline testing rate of 5 per 1000 population for all zip codes within the COH; and 2) make testing available to vulnerable populations. The initial baseline level of testing for all zip codes had a goal of 0.5%.

The Phase 2 strategy’s primary goal was to increase widespread access to testing based on weekly positivity rates.

Phase 1 required the identification of “Access Zip Codes” (areas with lowest testing penetration) and “Equity Zip Codes” (areas with vulnerable populations at greater risk for poorer health outcomes in terms of disease severity and likelihood of cases requiring critical care). The cross-section of these two groups were used to establish “Priority One Zip Codes”. The HHD, with testing partners, focused on setting up testing sites in these Priority One Zip Code areas during Phase 1. Once the Phase 1 level testing rate was achieved, the HHD moved to widespread access to testing based on weekly positivity rates. Phase 2 testing included fixed community-based testing sites, mobile testing that moves to high positivity zip codes, special population strike teams for vulnerable groups (long-term care facilities, homeless shelters, etc.), at-home testing for other vulnerable populations (elderly, disabled, etc.), and also support of testing by healthcare partners at FQHCS, hospitals, and commercial clinics.

Three steps were used to first establish the “access zip codes”.

Two surveillance data sets –a syndromic surveillance dataset that area laboratories submitted to the Centers for Disease Control and Prevention (CDC) that included positive COVID tests in the Houston area daily and the Houston Electronic Disease Surveillance System (HEDSS) – were examined and mapped at the zip code level.

80 zip codes common in both datasets were identified as having low testing penetration. This list was further filtered to include only zip codes with at least 30% of the population residing in the COH, resulting in 35 zip codes.

These 35 zip codes were prioritized into three tiers – Tier 1, 2, and 3 based low testing levels – and were coded as red, yellow, and green. Only red and yellow tiered zip codes were included in the final “access zip codes” group due to being far less than the baseline minimum of 5 tests for 1000 population.

Next, “equity zip codes” were established in two steps.

Existing data identifying neighborhoods with the risk of poor outcomes from a COVID infection was reviewed. A report developed by Dr. Stephen Linder from the UT School of Public Health was used to identify 31 zip codes that have 30% or more of its population in the COH and whose residents have vulnerabilities (60+ years of age, cardiovascular disease and/or respiratory illnesses, etc.) and would be more likely to experience poor outcomes in terms of disease severity and the likelihood of cases requiring critical care.

The poverty level of these 31 zips were examined. Poverty was used as a proxy for social, economic, and environmental disadvantage. Zip codes where 20% or more of the population live below the Federal Poverty Level were selected, and 20 zip codes were identified as “equity zip codes.”

Finally, to locate the priority zip codes for testing, zip codes that met the criteria for both access and equity were reviewed. This yielded 11 zips codes that were included in the final “Priority One Zip Codes” list. These 11 zip codes were mapped and overlaid with the COH Council Districts.

Phase 2 testing included fixed community-based testing sites, mobile testing that moves to high positivity zip codes, special population strike teams for vulnerable groups (long-term care facilities, homeless shelters, etc.), at-home testing for other vulnerable populations (elderly, disabled, etc.), and also support of testing by healthcare partners at FQHCS, hospitals, and commercial

Fixed testing sites that were free and easily accessible were established. Some sites were run solely by the HHD and others were managed by other partner organizations. These fixed site were strategically placed throughout the city to ensure that all COH residents had access to a testing site within 5 miles of their residence.

Mobile and Strike testing unit teams were established to testing needs. Mobile Teams offered testing based on location and geography and the need for disease containment using a data driven approach. Strike Teams offered testing in special populations or specific facilities. The Strike Team was informed by data from HEDSS as well as data from the wastewater testing treatment plant project. Routine weekly testing of wastewater by HHD, in collaboration with academic partners, from geographic areas that have congregate settings such as long-term care facilities, homeless shelters, and transitional care centers have informed the HHD of increasing or decreasing trend of infection from wastewater testing.

At-Home testing was made available for homebound and disabled populations, including seniors, elderly, disabled, veterans, and recently incarcerated individuals.

This data drive, strategic approach used to establish a city-wide testing plan ensured that COH residents had a baseline level of access to testing and that testing was equitable based on vulnerability.

Availability of syndromic surveillance data and collaborative reports developed by others in public health was essential in using this tiered approach to developing a priority testing plan. Flexible and cooperative partnerships with other testing organizations has also helped insured an equitable access to testing locations for the COH residents.

Houston COVID-19 Testing Plan to Address Access and Equity

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