Long-COVID in perhaps 16% of those who got COVID - May 2026
Long COVID Persistence and Surveillance Gaps Across 58 US Hospitals
JAMA doi:10.1001/jamanetworkopen.2026.14909
Key Points Question What is the true burden of chronic disease following COVID-19, and why does current surveillance fail to capture it?
Findings In this cohort study of 457 950 patients with COVID-19 across 58 hospitals, validated computable phenotyping identified postacute sequelae of SARS-CoV-2 infection in 16.28% of cases, 2-fold higher than diagnostic code–based surveillance. Of identified manifestations, 89.31% represented chronic conditions, with prevalence increasing through mid-2024.
Meaning These findings suggest that approximately 1 in 6 patients with COVID-19 develops postacute sequelae, predominantly chronic conditions currently invisible to surveillance systems, representing an accumulating rather than resolving health care burden.
Abstract Importance Surveillance of postacute sequelae of SARS-CoV-2 infection (PASC) depends on diagnostic coding systems that capture fewer than one-half of affected individuals, rendering millions invisible to health systems and policymakers.
Objective To quantify the gap between true PASC burden and diagnostic code–based estimates, determine the proportion representing chronic disease, and characterize organ system heterogeneity and temporal trends across diverse populations.
Design, Setting, and Participants This retrospective cohort study used electronic health record data from 58 hospitals and affiliated clinics in 4 US regions, from 2017 to 2025. Adults (aged ≥18 years) with laboratory-confirmed SARS-CoV-2 infection or a COVID-19 diagnosis code were included. A custom artificial intelligence algorithm, the Precision Phenotyping for Research Cohorts (P2RC), was implemented using federated infrastructure.
Exposure Laboratory-confirmed SARS-CoV-2 infection or COVID-19 diagnosis code.
Main Outcomes and Measures The primary outcomes were PASC prevalence, the proportion classified as chronic conditions, organ system distribution, and temporal trends from 2020 to 2024. χ2 Tests were used to assess organ system heterogeneity across regions, and negative binomial regression was used to model quarterly temporal trends, yielding incidence rate ratios (IRRs) with 95% CIs.
Results In this cohort study of 457 950 COVID-19 cases (mean age, 52.05 years; 275 107 [60.07%] female), the P2RC algorithm identified 74 560 PASC cases (16.28% overall; 28 585 [18.58%] in New England, 978 [19.55%] in Southeast Texas, 10 534 [22.69%] in Southern California, and 34 463 [13.64%] in Western Pennsylvania), more than 2-fold higher than the proportion identified by code-based surveillance (<7%). Of 883 International Statistical Classification of Diseases, Tenth Revision, Clinical Modification codes associated with PASC, 594 (67.27%) represented chronic or potentially chronic conditions. Of 74 560 patients with PASC, 66 587 (89.31%) developed chronic conditions requiring ongoing clinical management; this represents 14.54% of the total number of 457 950 patients with COVID-19. Substantial organ system heterogeneity was observed (χ2 = 2504.73; P < .001): New England demonstrated thyroid-predominant endocrine patterns, while Southeast Texas, Southern California, and Western Pennsylvania showed metabolic-predominant profiles. Negative binomial regression revealed increasing PASC prevalence through mid-2024 (IRR per quarter, 1.01 [95% CI, 1.00-1.01; P < .001] in New England; 1.00 [95% CI, 1.00-1.01; P < .001] in Southern California; and 1.02 [95% CI, 1.01-1.02; P < .001] in Western Pennsylvania), indicating an accumulating rather than resolving burden.
Conclusions and Relevance In this cohort study, approximately 1 in 6 patients with COVID-19 developed PASC, and 89.31% of these patients had at least 1 chronic condition. Current diagnostic coding captured fewer than one-half of the cases, obscuring a substantial chronic disease burden. The persistently increasing prevalence through 2024 indicated an accumulating health care burden requiring investment in surveillance infrastructure and integrated care pathways.
Invisible Epidemic? Long COVID Burden May Be Far Larger Than Surveillance Systems Capture - [TrialSite News] (https://www.trialsitenews.com/a/invisible-epidemic-long-covid-burden-may-be-far-larger-than-surveillance-systems-capture-81fc7e41) review of the study
"AI Surveillance Finds What Diagnostic Codes Miss"
Conclusion
This study strengthens growing concerns that Long COVID remains significantly underrecognized inside U.S. healthcare systems. While the findings do not establish direct causation for every chronic illness identified, they suggest millions of Americans may be living with persistent post-COVID conditions outside formal surveillance frameworks. The deeper implication is operational: healthcare systems may already be absorbing a major chronic disease burden without explicitly recognizing it as Long COVID. As debates over post-infectious syndromes and possible post-vaccination overlaps continue, the challenge confronting medicine may increasingly center on building more sophisticated surveillance systems capable of distinguishing—and managing—complex chronic immune-mediated conditions in the post-pandemic era.