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COVID-19 Observational Research Collaboratory

April 7, 2023

Takeaway: While assessing real-world vaccine effectiveness and outcomes, COVID-19 Observational Research Collaboratory (CORC) investigators provided several important insights into COVID-19. Among Veterans with comorbidities, the vaccine was 69% effective against COVID infection and 86% effective against COVID-related deaths. To provide these and other findings, CORC also stood up data and methods expertise and is sharing that expertise, codes, and algorithms with researchers, including early career scientists, to further speed analysis.

The COVID-19 virus has evolved over time, as have clinical, social, and economic factors. Treatments have also been developed, including vaccines, antivirals, and antimicrobials. With so many changing variables, it is important to understand how COVID-19 impacts Veterans, including both the acute and long-term effects of infection and illness.

The COVID-19 Observational Research Collaboratory (CORC) was established to conduct rigorous research to help us understand the long-term effects of SARS-CoV-2 infection, while fostering research collaborations within and outside VA. Nine principal investigators from around the country came together to build a platform that would facilitate the investigation of long-term outcomes of COVID-19 infection, including providing resources to help other researchers.

CORC includes two major components: the Coordinating Center (CCC) and the Long-Term Outcomes study. CORC is led by nine principal investigators (PIs) across four HSR&D Centers of Innovation. These PIs include Drs. George Ioannou, Denise Hynes, Amy Bohnert, Barrett Bowling, Ed Boyko, Theodore (Jack) Iwashyna, Matt Maciejewski, Ann O’Hare, and Elizabeth Viglianti.

The CORC Coordinating Center focuses on Data, Methods, and Partnerships. Led By Drs. George Ioannou and Ed Boyko, the Data Core is responsible for identifying Veterans with COVID-19 based on VA and Medicare data, and constructing exposures, covariates, confounders, and outcomes. They work to document this information and make it available as a resource. Led by Dr. Matt Maciejewski, an HSR&D Senior Research Career Scientist, the Methods Core is responsible for working with a team of methodologists to develop the final study design and measurement strategy, as well as a cohort-matching strategy. Matching of Veterans with infections identified between March 2020-April 2021 has been completed, and the team will have matched cohorts of Veterans with infections identified between May 2021-April 2022. The Methods Core will move into an advisory role for authorship teams working on the analyses of COVID outcomes. In addition, they will provide methodological consultation for others who want to study the effects of COVID-19. Led by Amy Bohnert, PhD, a core investigator with HSR&D’s Center for Clinical Management Research (CCMR), the Partnerships and Communication Core is identifying early career scientists that might benefit from CORC resources; this core is also responsible for disseminating COVID-19 research findings to Central Office and the field.

The CORC Long-Term Outcomes (LTO) Study is implementing mixed methods to examine and compare the long-term outcomes of COVID-19 infected Veterans with matched uninfected Veterans, with support and resources established in the Coordinating Center.  By triangulating a range of data sources the LTO study is comparing outcomes that can be measured using electronic health record data (led by Denise Hynes, HSR&D Senior Research Career Scientist), Veteran-reported outcomes from survey data (led by Jack Iwashyna, Barret Bowling, and Elizabeth Viglianti), Veteran experiences of recovery from semi-structured interviews (led by Ann O’Hare), and estimating current and future health system needs.

CORC also has engaged with the Long COVID Integrated Project team (ITP) on what patient-reported outcomes to focus on for Veterans visiting Long COVID clinics. The ITP is an important part of VA’s efforts to organize, support, and report on the development of a national program to help all Veterans who have Long COVID.

In assessing real-world vaccine effectiveness and outcomes, CORC investigators have already provided several insights into COVID-19:

  • In VA patients with comorbidities, vaccine effectiveness was 69% effective against COVID infection and 86% effective against COVID-related deaths (Ioannou et al, 2022).
  • Early associations between race and urban vs. rural and COVID mortality were erased or reversed by March 2021, highlighting VA’s effectiveness in discovering these outcomes (Ioannou et al, 2022).


Contributing to the COVID Shared Data Resource

One of the advantages of the CORC Partnerships Core is the outreach CORC is doing with other researchers about how data have evolved over time, and how to make better use of it. The data that CORC is constructing – cohorts for the 1st and 2nd years – will be made available on VINCI (VA Informatics and Computing Infrastructure) for others to use. This takes time. In the interim, CORC is making the codes and algorithms available about how those data have been constructed. This is important because CORC has a database of Veterans who were/are infected and matched comparators by many different characteristics. Sharing the code and algorithms used to make this database should allow other researchers to work more efficiently and faster.

Long-term Outcomes Study

There are analyses underway that will characterize long-term outcomes of Veterans who had COVID-19 and those who didn’t, including a mortality analysis, mental health outcomes assessment, including suicide risks; rates of VA and Medicare use; COVID-related costs a year or two after infection, as well as examining Veteran reported outcomes from survey data. The papers resulting from these analyses will also help CORC determine which questions still need answering in future research.

CORC conducts qualitative interviews with Veterans that allows them to tell their individual stories. CORC will glean insights about Veterans’ experience with COVID and what their recovery has been like. This feedback will be very important in understanding for how Veterans are dealing with the illness, as well as some of the social, economic, and other impacts of COVID-19.


Ioannou G, Baraff A, Fox A, et al. Rates and factors associated with documentation of diagnostic codes for Long COVID in the National Veterans Affairs Health Care SystemJAMA Network Open. July 29, 2022;5(7):e2224359.

O'Hare AM, Vig EK, Iwashyna TJ, et al. Complexity and challenges of the clinical diagnosis and management of Long COVID. JAMA Network Open. November 1, 2022;5(11):e2240332.

Admon AJ, Wander PL, Iwashyna TJ, et al. Consensus elements for observational research on COVID-19-related long-term outcomesMedicine (Baltimore). November 18, 2022;101(46):e31248.

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