New Study Reveals Long COVID Effects


Increased risk of post-acute conditions (PASC) in SARS-CoV-2 positive patients.

Doctor testing patient for COVID | Image Credits: Unsplash

In a retrospective cohort study published in BMC Infectious Diseases, investigators evaluated the incidence of certain symptoms and conditions associated with long COVID, potentially indicative of PASC, within 31 to 150 days after a SARS-CoV-2 test in both adults and children, comparing those with positive and negative results. Individuals infected with SARS-CoV-2, particularly those who required hospitalization, faced an increased risk of being diagnosed with specific symptoms and conditions following their acute infection phase.

Following adjustments for baseline covariates, adults and children who were hospitalized and tested positive showed higher odds of receiving a diagnosis of ≥1 symptom (adults: adjusted odds ratio (aOR), 1.17 (95% CI, 1.11–1.23); children: aOR, 1.18 (95% CI, 1.08–1.28) or experiencing shortness of breath, (adults: aOR, 1.50 (95% CI, 1.38–1.63); children: aOR, 1.40 (95% CI, 1.15–1.70) within 31–150 days after a SARS-CoV-2 test, compared to hospitalized patients who tested negative.

“We found that differences in symptoms and conditions following SARS-CoV-2 positive and negative test results were more evident among hospitalized patients than non-hospitalized patients,” investigators wrote. “These findings are consistent with literature reports showing that patients with more severe acute SARS-CoV-2 infection (i.e., hospitalized patients) have a higher risk of developing PASC conditions and symptoms. We found relatively small differences in symptoms and conditions between non-hospitalized patients who tested positive and those who tested negative.”

Adults hospitalized with a positive test were also more likely to be diagnosed with ≥3 symptoms or fatigue than those with a negative test. The likelihood of receiving a new diagnosis of type 1 or type 2 diabetes (adjusted hazard ratio (aHR), 1.25 (95% CI, 1.17–1.33), blood disorders (aHR, 1.19 (95% CI, 1.11–1.28), or respiratory conditions (aHR, 1.44 (95% CI, 1.30–1.60) was greater in hospitalized adults who tested positive compared to those who tested negative. Similarly, adults not requiring hospitalization but testing positive also showed increased odds or a higher risk of being diagnosed with specific symptoms or conditions.

3 Key Takeaways

  1. Hospitalized patients testing positive for SARS-CoV-2 are significantly more likely to develop symptoms or conditions indicative of PASC, such as shortness of breath, fatigue, and new diagnoses of diabetes or respiratory conditions, compared to those who tested negative.
  2. The study underscores the necessity for clinicians and public health agencies to closely monitor and address the lingering health impacts of COVID-19.
  3. The study indicates that hospitalized individuals face a higher risk of developing PASC.

The study utilized electronic health record (EHR) data from 43 PCORnet sites engaged in a nationwide COVID-19 monitoring effort. The analysis included 3,091,580 adults, with 316,249 testing positive for SARS-CoV-2 and 2,775,331 testing negative. Additionally, 675,643 children were part of the study, including 62,131 who tested positive and 613,512 who tested negative. All of them underwent a SARS-CoV-2 laboratory test between March 1, 2020, and May 31, 2021, as recorded in their EHRs. To assess the likelihood of exhibiting a symptom or the risk of being diagnosed with a new condition linked to a positive SARS-CoV-2 test, we applied logistic regression and Cox proportional hazards models.

“Clinicians and public health agencies should monitor for the development and persistence of symptoms and conditions after COVID-19, especially among those who are hospitalized,” wrote the investigators. “The higher burden of PASC symptoms and conditions post-COVID, especially among those with severe disease, also should encourage investment in clinical and public health resources needed to deliver care to treat and prevent PASC, including ongoing support for trials underway to evaluate the effectiveness of treatments for specific post-COVID conditions.”

This study shows several limitations that might have influenced its findings. The reliance on EHR data could underestimate the true prevalence and incidence of conditions due to missing diagnosis codes and the inability to capture all positive SARS-CoV-2 cases, especially those identified through self-testing at home. Variations in baseline period lengths and healthcare-seeking behavior could also bias results. Moreover, the study's method of identifying symptoms and conditions post-infection aims for sensitivity over specificity, potentially affecting the accuracy of its conclusions. Additionally, certain variables like vaccination status were not considered, and the criteria used to assess COVID-19 severity and subsequent health outcomes might have introduced misclassification biases.

All in all, results indicate a link between acute SARS-CoV-2 infection and the likelihood of experiencing post-acute sequelae, with specific symptoms and conditions being more prevalent in individuals who test positive for SARS-CoV-2. Further studies are needed to investigate ways to prevent and treat these post-infection symptoms and conditions, aiming to aid in the recovery process from SARS-CoV-2.


Zhang, Y, Romieu-Hernandez, A, Boehmer, TK, et al. Association between SARS-CoV-2 infection and select symptoms and conditions 31 to 150 days after testing among children and adults. BMC Infectious Diseases. Published February 10, 2024. Accessed February 13, 2024.

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