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Omicron linked to multisystem long COVID and GI symptoms in veterans study

Omicron linked to multisystem long COVID and GI symptoms in veterans study
Photo by Volodymyr Hryshchenko / Unsplash
Key Takeaway
Note associations between Omicron and multisystem long COVID in veterans, but causation is not established.

This retrospective cohort study analyzed 1,120 veterans treated at the Veterans Affairs Medical Center in Boise, Idaho. The study examined associations between SARS-CoV-2 viral variants, patient characteristics, and long COVID phenotypes, with follow-up from 90 to 270 days post-infection.

The primary outcome was phenotype prevalence for cardiopulmonary, neuropsychiatric, and multisystem long COVID. Compared to pre-Delta variants, Omicron variants were associated with increased prevalence of multisystem long COVID. Omicron infection was also associated with increased post-acute gastrointestinal symptoms.

Neuropsychiatric long COVID was more prevalent in female patients and less prevalent among older patients. Female patients also had less recovery. Recovery was less with Omicron variants relative to pre-Delta.

Safety and tolerability data were not reported. Key limitations include the retrospective design and a single VA center population, which may limit generalizability. The study investigates associations; Omicron findings may indicate an association, not causation.

Clinicians should interpret these findings cautiously, recognizing they are from an observational study of veterans and may not apply to other groups.

Study Details

Study typeCohort
EvidenceLevel 3
PublishedApr 2026
View Original Abstract ↓
PurposeTo investigate associations between cardiopulmonary, neuropsychiatric, and multisystem long COVID phenotypes, and sequence-defined SARS-CoV-2 viral variant and sociodemographic predictors in a population from a rural state.MethodsSARS-CoV-2 clinical samples were collected from 1,120 veterans treated at the Veterans Affairs (VA) Medical Center in Boise, Idaho from April 2, 2020 to December 20, 2022. Viral variants were identified through sequencing and annotated with clinical data from the VA Corporate Data Warehouse, as well as CDC rurality and social vulnerability. Cardiopulmonary, neuropsychiatric, and multisystem long COVID phenotypes were determined by the addition of one or more ICD-10 codes 90–270 days post-infection. Multinomial logistic regression was used to estimate phenotype prevalence in a base model with predictors viral variant, age, sex, rurality, and social vulnerability, as well as in models that adjusted for patient health (comorbidity, healthcare utilization, and smoking status), and treatments (vaccination and Paxlovid).FindingsFemale patients experienced more neuropsychiatric long COVID and less recovery, whereas the neuropsychiatric phenotype was less prevalent among older patients. Omicron variants had less recovery and more multisystem long COVID relative to pre-Delta—a finding that may indicate an association between infection with Omicron and post-acute gastrointestinal symptoms.ConclusionThis study is perhaps the largest to investigate viral variant effects on long COVID using sequence rather than date-based variant definitions, and is also unique in its focus on a population living in one of the most rural states in the United States. Our results are consistent with other studies finding contributions from both biological and social predictors to long COVID outcomes.
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