Herd immunity Archives – PCCI

7 July 2021

PCCI CEO Statement – Dallas County Reaches Herd Immunity, More Work To Be Done




Statement from PCCI CEO Steve Miff:

“On July 4, Dallas County reached the 80 percent herd immunity threshold. This threshold is made up

by 46.6 percent of the total population being vaccinated and 48.7 percent of the population with natural immunity having recovered from being infected by COVID-19.

While this represents good progress, it is important that we understand the work is not over. We must continue to push for vaccinations so COVID and its variants can’t again take hold and diminish the progress we’ve made. Reaching the 80 percent herd immunity rate is not like flipping a switch, but a continuum in our journey.  It is an important accomplishment which is a credit to the residents and public health leaders who have committed themselves to crush COVID. While the whole community in average reached the 80 percent mark, there are only 49 ZIP codes above the 80 percent threshold with 45 ZIP codes still below the 80 percent mark. There are still significant pockets in the community that remain vulnerable.

How we got here

The calculations used to measure heard immunity track individual level data for both vaccinations administered and COVID test results since the beginning of the pandemic.  For those infected, yet not tested there are a 4x Adjusted Incidence Rate Ratio [AIRR] for the adult population and 5x for the pediatric group based on national and local seroprevalence data. The model also calculates an overlap 28 percent of vaccinated population of Dallas estimated to have had prior COVID-19 infection and recovered.

Delta Variant

Further, the current Delta variant is predicted to make up about 25 percent of COVID-19 cases locally, doubling approximately every two weeks. In one month, that could put the Delta variant in the range that has caused a new wave in infections in the UK, though their estimated immunity was below the herd immunity threshold for Delta.

The significantly higher viral loads and more infectious nature of the Delta variant could put the herd immunity target as high as 88 percent to suppress infection spikes when the Delta variant becomes the dominant variant in a few weeks’ time.

Vaccinations Lag

As a county, we’re still behind on vaccinations: Only 38 percent of the total population with completed vaccination series and 47 percent of the total population with at least one dose (61 percent of adults and 80 percent of those over the age of 65 years).  While previous infections and partial vaccinations do provide a level of protection, all evidence suggests that full vaccinations are the most effective way to stay safe against the delta variant.

Why is getting vaccinated still very important:

  • Infections remain very low for those vaccinated – local data from Parkland and the Dallas County Health & Human Services Department suggests an infection rate of only 0.04 percent for those vaccinated. Getting vaccinated doesn’t only protect you, but those around you, including the children who are not yet eligible for a vaccine.
  • Long COVID (prolonged COVID related symptoms such as fatigue, brain fog, muscle pain, shortness of breath, and loss of taste and smell) is prevalent in 10-30 percent of those infected and mortality for those unvaccinated is still a concern. Not getting vaccinated is rolling the dice on dying or dealing with long-term medical issues. 

The message is simple: don’t wait to get vaccinated. For those still hesitant, the safety and efficacy studies to date are overwhelmingly positive.  There are also two key upcoming milestones that should give further confidence to those who remain hesitant: Full FDA approvals for the mRNA vaccines expected in the upcoming weeks and approval for the under 12-year-old groups in the fall.”

-Steve Miff, PhD, President & CEO of Parkland Center for Clinical Innovation (PCCI) 

To monitor herd immunity and vaccination progress in Dallas County go to PCCI’s COVID-19 Vaccination and Herd Immunity Dashboard hosted on the Dallas County Health and Human Services’ website: https://www.dallascounty.org/covid-19/.

Background on PCCI’s herd immunity measurements

PCCI’s forecast for herd immunity is based on an innovative yet vetted statistical and immunological model and analysis of spread and management of diseases within communities. Further, PCCI’s 80 percent range for reaching herd immunity is in line with national estimates, such as that of Anthony S. Fauci, MD, Director of the National Institute of Allergy and Infectious Diseases, who recently gave a range of 70 to 90 percent and the World Health Organization which gave a 60 to 70 percent range of infections and vaccines to reach herd immunity*.

PCCI’s forecast and estimates have been developed in coordination with community health leaders in Dallas County, including the DCHHS and Parkland Health & Hospital System.  Recently, PCCI has been collaborating with the leadership and expert teams at the Institute for Health Improvement on modeling.

*New York Times, Dec. 24, 2020: “How Much Herd Immunity Is Enough?”

https://www.nytimes.com/2020/12/24/health/herd-immunity-covid-coronavirus.html

 

6 July 2021

News Release: PCCI, Dallas County Release COVID-19 Vaccination and Herd Immunity Dashboard




Dallas, Texas – Parkland Center for Clinical Innovation (PCCI), which improves healthcare for vulnerable populations using advanced data science and clinical experts, has developed a COVID-19 Vaccination and Herd Immunity Dashboard to give residents of Dallas County up-to-date data about herd immunity levels, infections and vaccinations rates and corresponding demographic information.

The Dallas County Health and Human Services Department (DCHHS) will host the COVID-19 Vaccination and Herd Immunity Dashboard, which will supplement its rich set of COVID-19 resources. The COVID-19 Vaccination and Herd Immunity Dashboard can be accessed here: https://www.dallascounty.org/covid-19/

The COVID-19 Vaccination and Herd Immunity Dashboard provides exclusive data for Dallas County, including herd immunity by percentage of the county’s population at the ZIP code level. This is helpful for monitoring the county’s efforts to drive vaccination efforts to reach the herd immunity threshold of 80 percent of the whole county’s population who either have recovered from COVID-19 or who have received vaccinations. The dashboard’s data also includes vaccinations by manufacturer, estimated active COVID cases and important information resources about the pandemic.

“The COVID-19 Vaccination and Herd Immunity Dashboard provides the relevant available information to help estimate how far along Dallas County is toward reaching the herd immunity goal as well as the rates of vaccinations across the whole community,” DCHHS Director Dr. Philip Huang said. “It is important that we understand that once the indicators suggest that we are at the estimated herd immunity threshold, the work is not over. We need to continue the push for vaccinations, which is the crucial element to reaching herd immunity. The data in this dashboard will allow us to monitor our fight against COVID in every corner of the county in order for us to take the necessary steps to maintain our positive momentum.”

For each ZIP code in Dallas County, the COVID-19 Vaccination and Herd Immunity Dashboard also includes insightful, localized vaccination demographic information, such as ethnicity, age, sex and race. This data is used to continue to ensure equity in all our efforts and to continue to reach the population in the most convenient and effective way.

“This is critical information that we need to guide and coordinate our efforts. Dallas County is unique in the country for having these analytics available at such localized levels for all of our residents,” said Dr. Steve Miff, PCCI’s President and CEO. “The way we crush COVID is by coming together as a community and the information from the dashboard empowers everyone with knowledge on what is happening where they live― what the herd immunity level is and what the vaccination level is so they may act accordingly to maintain their safety and that of their families.”

In February, PCCI forecast that Dallas County would reach the 80 percent herd immunity threshold in June. However, that forecast has been pushed back to July due to slowing vaccination rates.

“Our progress toward herd immunity in Dallas County is making a difference as we have seen with slowing rates of community transmission, and it is so important that we aggressively continue our community efforts to vaccinate,” said Dr. Huang. “With the knowledge we gain from the COVID-19 Vaccination and Herd Immunity Dashboard, we can empower all our citizens with the information to stay safe. Vaccines are the best line of defense against COVID-19 and its variants, so it is critical that as many county residents as possible receive a vaccine.”

PCCI’s forecast for herd immunity is based on an innovative yet vetted statistical and immunological model and analysis of spread and management of diseases within communities. Further, PCCI’s 80 percent range for reaching herd immunity is in line with national estimates, such as that of Anthony S. Fauci, MD, Director of the National Institute of Allergy and Infectious Diseases, who recently gave a range of 70 to 90 percent and the World Health Organization which gave a 60 to 70 percent range of infections and vaccines to reach herd immunity*.

PCCI’s forecast and estimates have been developed in coordination with community health leaders in Dallas County, including the DCHHS and Parkland Health & Hospital System. Recently, PCCI has been collaborating with the leadership and expert teams at the Institute for Health Improvement on modeling.

The COVID-19 Vaccination and Herd Immunity Dashboard supports the Google Chrome, Microsoft Edge and Mozilla Firefox web browsers.

About Parkland Center for Clinical Innovation
Parkland Center for Clinical Innovation (PCCI) is an independent, not-for-profit, healthcare innovation organization affiliated with Parkland Health & Hospital System. PCCI leverages clinical expertise, data science and social determinants of health to address the needs of vulnerable populations.
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*New York Times, Dec. 24, 2020: “How Much Herd Immunity Is Enough?”

20 May 2021

Herd Immunity Forecast For Dallas County Pushed Back to Late July




  • More natural immunity; decreasing vaccination rates   
  • Data from new UT Southwestern seroprevalence study raises PCCI’s county wide previously infected estimates to 48% of the total population;   
  • Herd immunity rate increases to 74 percent of the total population 
  • PCCI now forecasts Dallas County to surpass COVID herd immunity by late July 

Parkland Center for Clinical Innovation (PCCI) has updated its herd immunity forecast for COVID-19 in Dallas County. The new herd immunity analysis includes the up-to-date vaccination percentages for Dallas County as well as a change in the percentage of residents confirmed and presumed to have been infected. These factors indicate that the county’s herd immunity rate is now 74 percent of the total population. However, a continued decrease in vaccinations pushes reaching the herd immunity threshold of 80 percent of all residents either having been infected or being vaccinated towards late July. 

PCCI made its initial herd immunity forecast for Dallas County in February, where it predicted the county would reach the herd immunity threshold by mid-June.  

 “The most critical factor in the fight to crush COVID remains vaccinations for the whole population, particularly with the county’s younger, working population and the recently approved high school and middle school students,” said Steve Miff, PhD., PCCI’s President and CEO. “Convenience, missed work or school from vaccine side-effects, and concerns about providing identifications for the transient and un-documented populations remain as key barriers to vaccinations and continue to be a key decision driver for the 20-30 percent of the unvaccinated population who are not opposed to receiving a vaccine, but have not yet rolled up their sleeves.” 

 An important new UT Southwestern virologic study indicates a ratio of 1:4 for confirmed positive (tested and confirmed) to presumed infected (positive antibodies, but never tested) population for Dallas County.  With this information, PCCI has updated the presumed infected adult population from a 1:3 ratio to the 1:4 ratio. This increase in the presumed infected results also in adjustment of the vaccinated population of Dallas estimated to have had prior COVID-19 infection and recovered from 21 percent to 28 percent.   

 For vaccinations, the weekly average is slowing below 15,000 first doses/week despite new age group approval for 12-15-year-old. To date, 1,018,696 people in Dallas County have been vaccinated, with 798,775 being fully vaccinated.  This indicates that approximately 40 percent of the whole county population, 52 percent of the over 18-year-old population, and 77 percent of the over 65-year-old have received at least one dose of the vaccine.   

The net results increase the current county wide herd immunity rate to 74 percent of the total population.  Twenty-six Dallas County ZIP codes are estimated as surpassing the 80 percent threshold to date.  

  

 Figure Above: COVID-19 Herd Immunity Current State, Dallas County, May 13, 2021; base population based on US Census ACS 2019 5 year; values capped at maximum of 0.8 to show relative progress; eastern zip codes in county tend to be sparser and cover a larger area; estimates may have variance across county estimates; using 4x AIRR based on UTSW seroprevalence data as best local estimate. Overlap estimate of 28% of vaccinated population of Dallas estimated to have had prior COVID-19 infection and recovered. 

 Significant plans are already underway to address convenience and access. PCCI has created an updated Vulnerability Index calculation and identified the top 100 neighborhoods with the most unvaccinated individuals (map below).  The map shows areas of low vaccination rates sprinkled across north and central Dallas County, but it indicates large sections of the southern half of the county have many unvaccinated. These areas in south Dallas often experience transportation gaps to access certain vaccination sites.  

Dallas County, City of Dallas and the Parkland Health and Hospital System are coordinating efforts to bring local community vaccination clinics to high risk, high opportunity locations.  There are 29 recent, active, and planned community locations to where individual can receive a COVID vaccine in their own neighborhood.   These are in addition to the local pharmacies, physician offices and other activities by many local health systems.   

  

Above Image: The dotted red areas indicate neighborhoods with highest numbers of unvaccinated individuals. 

“With this new analysis, we are able to pinpoint where the least vaccinated populations are in the county,” said Dr. Miff. “Our public health leaders are taking action and making progress toward reaching those areas, but each of us can take responsibility to quickly receive our vaccine and encourage our friends and neighbors to do the same, especially for those who live in neighborhoods with the low vaccination rates. Vaccines are the fastest and safest way we can get back to any sort of normal.” 

Why does it matter that we get to herd immunity through vaccinations instead of infection? 

Reaching herd immunity will significantly reduce the spread of the virus but reaching the 80 percent with equal numbers of vaccinated and natural immunity populations will not make the virus go away. For areas already at or above 80 percent, and for the rest of the county, until vaccination rates increase, there will likely continue to be low levels of constant infections, hospitalizations and periodic deaths.   

 “The virus will continue to linger in the background at relatively low and steady rates, with the periodic flareup. The best thing we can do is continue to vaccinate to reach and surpass the 80 percent vaccination mark and then drive both personal and community protection through the vaccines,” said Dr. George ‘Holt’ Oliver, Vice President of clinical Informatics at PCCI. 

 For more information about how PCCI has taken the fight to COVID-19, go to: https://pccinnovation.org/taking-the-fight-to-covid-19/. 

 About Parkland Center for Clinical Innovation  

Parkland Center for Clinical Innovation (PCCI) is an independent, not-for-profit, healthcare intelligence organization affiliated with Parkland Health & Hospital System. PCCI leverages clinical expertise, data science and social determinants of health to address the needs of vulnerable populations.   

  

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14 April 2021

PCCI’s Vulnerability Index Shows Lowest COVID-19 Infection Risk Level for Dallas County




DALLAS – Towards the end of March, Parkland Center for Clinical Innovation’s COVID-19 Vulnerability Index has recorded the lowest infection risk since the Vulnerability Index launched in June of last year.

“After the holidays, we had vulnerability index ratings at nearly 200, which meant the COVID-19 virus was running rampant through our community,” said George “Holt” Oliver, MD, Vice President of Clinical Informatics at PCCI. “It is a great relief to see that the highest vulnerability index rating now is only 16.91. This is a triumph for our county’s public health leaders, providers and residents who have made the sacrifices and efforts needed to bend the curve.”

One of the hardest hit ZIP Codes during the past year, 75211, which includes the areas around Cockrell Hill and Oak Cliff, saw its vulnerability risk hit the high of 196.9 in January. This was the highest level any ZIP code in Dallas County reached. By mid-March, its vulnerability rating was 8.74, a dramatic improvement for an area facing some of the most sever socioeconomic issues.

“This is very good news for the residents of the 75211 ZIP code; however, we advise caution going forward,” said Dr. Oliver. “I believe that our new normal will be continued vigilance. To keep COVID-19 from resurging, everyone who can be vaccinated should seek it, and adhere to local health official guidance that includes direction on social distancing and face covering.”

Launched in June 2020, PCCI’s Vulnerability Index identifies communities at risk by examining comorbidity rates, including chronic illnesses such as hypertension, cancer, diabetes and heart disease; areas with a high density of populations over the age of 65; and increased social deprivation such as lack of access to food, medicine, employment and transportation. These factors are combined with dynamic mobility rates and confirmed COVID-19 cases where a vulnerability index value is scaled relative to July 2020’s COVID-19 peak value. The PCCI COVID-19 Vulnerability Index can be found on its COVID-19 Hub for Dallas County at: https://covid-analytics-pccinnovation.hub.arcgis.com/.

Currently, the 75150 ZIP code, at the intersection of Interstate Highway 30 and 635 has the highest COVID-19 risk at 16.91, down from a high of 107.30 in January. The ZIP code 75204, in east downtown Dallas, has the second highest vulnerability level at 15.81, down from a high of 126.5 in January.

PCCI’s forecast of Dallas County reaching COVID-19 herd immunity is still on-track but reaching that threshold is highly dependent residents receiving their vaccinations.

“With vaccinations available to all adults, we need to get in line and get immunized,” said Dr. Steve Miff, PCCI President and CEO. “We don’t want another year to go by where grandparents can’t hug their grandchildren. We have seen how safe and effective the current vaccines are, so it is the responsible thing to do for our friends, families and co-workers to get immunized.”

While always concerning when adverse reactions emerge, the action by the FDA to pause the J&J vaccine is out of “abundance of caution” and it’s a strong signal of how responsive they are to any potential safety concerns. Cerebral venous sinus thrombosis (CVST) with J&J vaccine has been reported in 6 young women (ages 18-48) among 6.8 million doses in the US. To date, Dallas County has administered 61% Pfizer, 35% Moderna, and 4% J&J. The syndrome has been dubbed vaccine-induced immune thrombotic thrombocytopenia.(VITT), based on a similar syndrome after the commonly-used medication heparin abbreviated HITT. The reported rates are much lower than IV Heparin which is used frequently in the hospital. While the risk benefit ratio of continuing to use J& J vaccine in the US COVID-19 vaccination plan may still make sense given the observed case fatality rate of 1.8% of COVID-19, prudence to understand the situation given the FDA emergency use authorization for use is warranted..

The FDA pause for the J&J vaccine will not significantly impact the PCCI initial estimate for Dallas County’s path to herd immunity by June. We were progressing towards herd immunity at a rate of approximately 3% per week, which was ahead of initial predictions. While the allocations for J&J were scheduled to increase and the latest developments will pause those vaccinations likely for days, up to several weeks, we forecast that Dallas county will continue to make progress at 2-2.5% per  week, which maintains the pace for mid-June.

A year in retrospective
With the COVID-19 pandemic ongoing for over a year, PCCI identified the zip codes with the highest average vulnerability from July 2020 through March 2021. These represent areas which have faced the highest risk during the COVID-19 pandemic to date.

Data Sources:
To build Vulnerability Index, PCCI relied on data from Parkland Health & Hospital System, Dallas County Health and Human Services Department, the Dallas-Fort Worth Hospital Council, U.S. Census, and SafeGraph.

About Parkland Center for Clinical Innovation
Parkland Center for Clinical Innovation (PCCI) is an independent, not-for-profit, healthcare intelligence organization affiliated with Parkland Health & Hospital System. PCCI leverages clinical expertise, data science and social determinants of health to address the needs of vulnerable populations. We believe that data, done right, has the power to galvanize communities, inform leaders, and empower people.

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Authors

Steve Miff, PhD., President & CEO of PCCI, George “Holt” Oliver, MD, Vice President of Clinical Informatics at PCCI and  Thomas Roderick, PhD, Senior Director of Data and Applied Sciences at PCCI.

10 March 2021

PCCI CEO Steve Miff’s Statement on Changing Texas COVID-19 Mask Policies




23 February 2021

PCCI Forecasts that Dallas County to reach COVID-19 Herd Immunity by mid-June




Dallas, Texas – Parkland Center for Clinical Innovation (PCCI), which improves healthcare for vulnerable populations using advanced data science and clinical experts, estimates Dallas County will reach a critical tipping point of COVID-19 “herd immunity” in late-June due to total case recoveries and vaccinations.

PCCI forecasts that Dallas County is on track to have 80 percent of the county residents at levels of COVID-19 “herd immunity” by early summer. This forecast is based on models estimating individuals who either have recovered from COVID-19 or who have received vaccinations.

“Our forecast is determined by the data, models and trends we have been monitoring and analyzing since the beginning of the pandemic and informed by the latest national and international research. We are optimistic that by early summer, much of Dallas County will reach herd immunity,” said Steve Miff, PhD, President and CEO of PCCI. “We will get to herd immunity either through continued infection, which is a slow route that will continue to harm the community and economy, or vaccinations. This underscores the importance of Dallas County residents registering for and receiving the COVID-19 vaccinations as quickly as possible and continuing to stay vigilant and safe from being infected. We’re also racing to stay ahead of the development and spread of existing or future new COVID-19 strains. We are in this together and will only get there though our collective and combined efforts.”

PCCI’s analysis, as of Feb. 22, indicates that the county has already reached 44 percent of the 1.9 million adult residents of Dallas County as either recovered from COVID-19 or in the process of receiving their full COVID-19 vaccine. That includes 922,460 COVID-19 confirmed and presumed infected and recovered, and 270,642 residents who have received their first (154,766) and second (115,875) vaccine shot.

“Reaching the tipping point for herd immunity is achievable with continued community effort,” said Thomas Roderick, PhD, Senior Director of Data and Applied Sciences at PCCI. “But parts of the county may not share the early benefits in our estimated forecast if they don’t keep pace with vaccines. Vaccines are also the best line of defense against COVID-19 variants, so it is critical that vaccines are made available to as many people as possible and county residents make it a priority to get vaccinated.”

PCCI’s forecast for herd immunity is based on widely accepted statistical analysis of spread and management of diseases within com

munities. Further, PCCI’s 80 percent range for reaching herd immunity is in line with national estimates, such as that of Anthony S. Fauci, MD, Director of the National Institute of Allergy and Infectious Diseases, who recently gave a range of 70 to 90 percent and the World Health Organization that gave a 60 to 70 percent range of infections and vaccines to reach herd immunity*.

PCCI’s forecast and estimates have been developed in coordination with and reviewed by community health leaders in Dallas County including experts at UT Southwestern Medical Center, Dallas County Health and Human Services and Parkland Health & Hospital System.

“Our predictions for Dallas County to reach its herd immunity tipping point include algorithms to predict total infections and forecasts of vaccination rates. We encourage the community to participate in virological studies such as the one conducted by our colleagues at UT Southwestern (https://utswmed.org/covidstudy/) so we can better understand the community infections and impact. We also need to register and vaccinate the most vulnerable as well as the rest of the population as soon as they are eligible,” said George ‘Holt’ Oliver, MD, PhD, Vice President of Clinical Informatics at PCCI.

PCCI will update its forecast monthly to understand how well the county is progressing toward its 80 percent vaccinated and infected and recovered rate. The updates will incorporate the latest data, intelligence and information from new studies, research and developments regarding the COVID-19 pandemic and impact of emerging strains.

PCCI has made available an important tool to help Dallas County residents stay vigilant and understand their personal risk, the MyPCI App, a free wed-base app that will help individuals make informed choices by providing an on-demand, location-based personal risk assessment of possible COVID-19 exposure. MyPCI is a sophisticated machine learning algorithm, geomapping and hot-spotting technology that uses daily updated data from Dallas County Health and Human Services (DCHHS) on confirmed positive COVID-19 cases and the population density in a given neighborhood. Based on density and distances to those nearby who are infected, the MyPCI App generates a dynamic personal risk score.

To use the MyPCI App, go to, https://pccinnovation.org/mypci/, click on the link and register (Using code: GP-7xI6QT). Registration includes a request for individual location information that will be used only for generating a risk assessment, never shared. Once registered, simply login daily and a COVID-19 personal risk level score will be provided along with information to help individuals make informed decisions about how to manage their risk.

About Parkland Center for Clinical Innovation
Parkland Center for Clinical Innovation (PCCI) is an independent, not-for-profit, healthcare intelligence organization affiliated with Parkland Health & Hospital System. PCCI leverages clinical expertise, data science and social determinants of health to address the needs of vulnerable populations.

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*New York Times, Dec. 24, 2020: “How Much Herd Immunity Is Enough?”
https://www.nytimes.com/2020/12/24/health/herd-immunity-covid-coronavirus.html

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