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The Burden of COVID-19 on Primary Care

Publish Date
Read Time
June 29, 2021

Understanding the impact of “long COVID.”

Jonah Leshin¹ and Dustin D. French, PhD²³⁴

  1. Datavant Inc. San Francisco, CA, USA
  2. Center of Innovation for Complex Chronic Healthcare, Edward Hines, Jr. VA Hospital, Department of Veterans Affairs, 5000 South 5th Ave., Hines, IL 60141, USA
  3. Center for Health Services and Outcomes Research, Feinberg School of Medicine, Northwestern University, 633 N. St. Clair St. Suite 2000, Chicago, IL, 60611, USA
  4. Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Ave. Suite 440, Chicago, IL, 60611, USA


There is growing interest in understanding the patient impact of COVID-19 not just during an acute case, but long afterwards. The mounting evidence of longer-term mental and physical effects suggests a need for better understanding of care requirements beyond the emergency room.

The implications of “long COVID” have had a tangible impact on primary care, where patients often receive follow-up treatment. The situation has been particularly acute considering that primary care was already under-resourced and facing a myriad of challenges prior to the pandemic.

This study analyzes the volume of primary care follow ups to ER visits introduced by COVID-19, illustrating the burden on a fragile system after an initial emergency room visit.

Data Sources:

We used Medical Claims Data that contain patient demographics, diagnoses, procedures, providers, service dates, and billing information (e.g., doctor, facility, and insurance carrier). The data set used contains > 3 billion claims on > 100 million unique patients over the last 7 years. The data set indicates whether a patient was diagnosed as COVID-19 positive. The data comes from Office Ally, a full-service medical claims clearinghouse that provides numerous software products to providers and patients.

Additionally, we used the National Plan and Provider Enumeration System (NPPES) National Provider Identifier (NPI) registry in combination with the National Uniform Claim Code (NUCC) to identify primary care providers.


Our base population studied consisted of patients with a record containing a COVID-19 diagnosis and emergency room visit. We then analyzed the volume of primary care follow ups for these patients. We obtained primary care follow up counts by totaling the number of primary care visits with a COVID-19 diagnosis, where the visit occurred between 1 and 60 days after the date of the initial emergency room visit. We counted multiple visits for the same patient as distinct visits.


Figure 1 shows the total number of unique monthly patients in the dataset who had an emergency room visit with a Covid diagnosis. It contains COVID-19 ER use by age bands, and shows age 55+ with the most pronounced ER utilization, up to 10 times greater than those ages 0–18, up to 4 times those ages 19–35, and more than double those ages 36–54. We saw spikes in all age groups for July and December 2020, with the December spike significantly larger.

Figures 2, 3, 4 and 5 show the number of Covid related follow up visits for primary care and primary care plus specialty care apart from ER visits expressed as a ratio (follow up visits/initial ER patients), limited to within 60 days of the initial ER visit. Months in these figures represent the month of the initial ER visit. These metrics can be thought of as an average number of follow up visits per ER patient.

As one might expect, our results show that the volume of follow up care required increases with age.

Both health care follow up types paralleled a spike in ER use, suggesting importance of subsequent non ER care after infection. Notably, however, although the second spike in ER visits is larger by absolute count (demonstrated in Figure 1), the spike in the average amount of follow up care required is actually smaller than the initial spike of average follow up care required in July 2020 across all age bands. This may be attributable to more effective initial ER treatment or home self-care as more about the disease was learned.

Finally, Figure 6 breaks down follow up care by the time interval between the initial ER visit and the follow up. It shows a positive correlation between age and follow up time intervals — that is, follow ups from younger patients occurred within less time of the initial ER visit.


The COVID-19 pandemic resulted in surges of cases and emergency room use that crippled the U.S. healthcare system. The results of this study suggest that primary care utilization mirrors emergency room use, and likely off-sets a fragile hospital system that was on the brink of collapse at different points in time. Future public health policies for pandemic and crisis response should go beyond the hospital safety net to consider the importance of primary care practitioners.


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Figure 6: For primary care and non-ER follow up visits with Covid diagnoses following ER visits with Covid diagnoses, the percentage breakdown of the time interval between the initial visit and the follow up, broken down by age range.

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