The C-19 Vulnerability Survey

Assessing Vulnerability to Serious Illness from COVID-19

A Tool to Help Individuals Safeguard Themselves and Their Loved Ones

  • The COVID-19 Vulnerability Survey (C-19 Vulnerability Survey) is a tool for individuals to use that helps them understand whether they or a loved one have a heightened vulnerability to severe illness from COVID-19  
  • The survey fills an unmet need to help people gain a more complete view into their own vulnerability as they safeguard themselves and their loved ones
  • The C-19 Vulnerability Survey can be used by local providers and public health authorities and easily integrated into local efforts
  • The survey is free, broadly available, and can be readily accessed through multiple channels, including web, iPhone and Android apps 
Austin, TX  April 15, 2020 —, Healthcare’s Data Science Platform, announced the release of the COVID-19 Vulnerability Survey (C-19 Vulnerability Survey), a tool designed for individuals to help them understand whether they or a loved one have heightened vulnerability to severe illness from COVID-19.   By releasing the free C-19 Vulnerability Survey, ClosedLoop aims to help individuals safeguard themselves and their loved ones.The Survey does not predict whether a person will actually get coronavirus.  Instead, it calculates a person’s vulnerability to severe illness should they contract COVID-19 and compares it to the average vulnerability for adults with no known risk factors. 

By taking the C-19 Vulnerability Survey, people gain a deeper understanding of what creates heightened vulnerability to severe illness, a more complete view into their own vulnerability or that of a loved one, and a tool to help them as they work to mobilize resources that safeguard their health and the health of their families.  “Everyone is worried about someone, and the impact of COVID-19 can be devastating. To help prevent that, the C-19 Survey is the latest in the data-driven arsenal of tools we’re creating that help organizations and now individuals fight COVID-19,” said ClosedLoop CEO, Andrew Eye.  

The tool is free and broadly available and can be readily accessed through multiple channels, including web, iPhone and Android apps.  

C-19 Vulnerability Survey – How It Works

The survey, designed for use by adults, asks a short series of questions and calculates an individual’s vulnerability to severe illness from COVID-19.  Since everyone is susceptible to the virus, a person without any known risk factors is scored as having ‘Normal Vulnerability’. Adding risk factors increases one’s Vulnerability Score.  The final score calculates a person’s ‘Elevated Vulnerability’ relative to an adult with no known risk factors and shows the degree to which they are more vulnerable than the rest of the population.

The tool also includes a brief set of questions asking whether they have experienced any recent symptoms known to be consistent with COVID-19 infection.  This information, when combined with the Vulnerability Score, can be especially useful when communicating with providers or loved ones.

The C-19 Vulnerability Survey – Filling an Unmet Need

The CDC guidelines for COVID-19 state that older adults and people of any age with certain health conditions may have a higher risk of severe illness from COVID-19.  This heightened risk, which has been seen in other countries, is starting to emerge in the U.S.   

The CDC guidelines identify factors that lead to ‘Elevated Risk’ that, when applied to Medicare beneficiaries, categorizes 59 percent – nearly 39 million people – as having ‘Elevated Risk’.  These criteria don’t reflect individual differences or identify the most vulnerable.

There is an unmet need to help people understand their individual level of vulnerability.  People with the same chronic condition may not have the same risk, and many people with a particular condition also have other comorbidities, which compounds their vulnerability.  

To illustrate, the Vulnerability Scores for two women — 45 and 65 years old and each diagnosed with hypertension — can be quite different.  The 45 year old is 3.4 times more vulnerable to severe complications from COVID-19 than a person with no established risk factors, and the 65 year old is 8.1 times more vulnerable.  Were each woman also obese, these scores would become 6.8 times and 14.7 times, respectively.

The need for this focus was highlighted recently by Dr. Deborah Birx, the White House Coronovirus Coordinator, who spoke to the need to identify the most vulnerable individuals.  

The C-19 Vulnerability Survey fills this unmet need.  It gives people a deeper understanding of what creates vulnerability to severe complications from COVID-19 and tells them the extent to which they or a loved one have heightened vulnerability.  “I used the survey to score my mother’s vulnerability,” said Carol McCall, Chief Health Analytics Officer, ClosedLoop. “Until she passed away last year, my father was her devoted caregiver. When I told him her score, he was shocked by just how vulnerable she was.  He began describing how immediately vigilant he would have become to safeguard her health.”   

Using the C-19 Vulnerability Survey

By gaining a more complete view into their own vulnerability or that of a loved one, individuals have a tool they can use as they mobilize resources to protect themselves and their families.  It can also be used by local providers and local health authorities as they work to connect vulnerable individuals with practical ways to help them ‘shelter in place’.   

For vulnerable individuals, protecting their health often include efforts to:

  • Educate.  Talk with people about COVID-19  
  • Promote safe practices. Make sure people know how to protect themselves
  • Ensure supplies. Make sure people have key household items 
  • Create a care plan.  Create a plan to monitor conditions and contact providers 
  • Look for Additional Challenges.  Help resolve challenges faced by people who are isolated, face housing or transportation issues, or have lower incomes
  • Be present / check-in. Give people a resource

Developing the C-19 Vulnerability Survey

The C-19 Vulnerability Survey combines risk factors in the CDC guidelines (e.g. heart disease), other known risk factors for poor respiratory infection outcomes (e.g. cystic fibrosis), and factors learned directly from data using AI-based machine learning to develop the C-19 Index.   Taken together, these factors form the basis of questions that are used to assess an individual’s vulnerability to severe complications from COVID-19.

The COVID-19 virus is novel but has recognizable similarities to known viruses that scientists are using to establish what to expect in terms of mechanisms and pathophysiologies until data on COVID-19 infections becomes available.  Because COVID-19 manifests as a severe respiratory infection, the C-19 Index was developed using severe respiratory infections (e.g. pneumonia, influenza) as proxy events, and calculates a person’s vulnerability to near-term risk of severe complications from respiratory infections.  

The first step in the development of the C-19 Vulnerability survey was to extract the risk factors from the C-19 Index that predict vulnerability and combine them with risk factors in the CDC guidelines.  These factors were then translated into questions whose responses could be weighted and aggregated so as to accurately reproduce the C-19 Index scores. The specific questions and response frameworks were modeled and adapted using national health research surveys as reference surveys.  


ClosedLoop is Healthcare’s Data Science Platform.  We make it easy and affordable for healthcare organizations to use data science to improve quality and reduce costs.  

The platform is purpose-built to make healthcare-focused data scientists more effective at their jobs.  By providing off-the-shelf models for common healthcare use cases and automating many of the manual processes involved in traditional data science tasks, ClosedLoop allows data scientists to focus on the impactful problems that drive real value for organizations.  A finalist in the Center for Medicare and Medicaid Services’s AI Health Outcomes Challenge, ClosedLoop is headquartered in Austin, Texas. For more information, visit and

More About the C-19 Vulnerability Index

ClosedLoop recently released the CV19 Vulnerability Index (C-19 Index), an open source, AI-based predictive model that identifies people with heightened vulnerability to severe complications resulting from COVID-19 (commonly referred to as “The Coronavirus”).   

The C-19 Index was created to help care management teams – whether they work within ACOs, health plans, hospitals or other organizations – safeguard the most vulnerable and reduce the impact of COVID-19 in their communities. Protecting vulnerable individuals also helps to protect the healthcare system, healthcare workers, first responders and other vital community resources from becoming overwhelmed. 

The C-19 Index is valuable because it is 10x more precise than ‘Elevated Risk’ category guidelines.  The first C-19 Index deployment saw that the majority of poor outcomes were concentrated in a small percent of the population, with five percent of people having 68 percent of serious illness. Care teams are using the C-19 Index to target and prioritize outreach to help the most vulnerable individuals.  

Thus far, the C-19 Index has been deployed to affect more than 10 million lives.