The New England Journal of MedicineLong COVID Defined

Long COVID Definition Bridges Patient Experience and Clinical Understanding, Highlighting Links to Other Infection-Associated Chronic Conditions

The National Academies of Sciences, Engineering, and Medicine (NASEM) has developed a new definition for long COVID, addressing the need for a standardized approach to this complex condition. The 2024 NASEM definition, created through extensive engagement with patients, clinicians, and researchers, aims to improve diagnosis, research, and patient care. This comprehensive definition emphasizes the chronic nature of long COVID, its diverse manifestations, and its potential to significantly impact patients’ lives.

Key Points:

• Long COVID is defined as an infection-associated chronic condition occurring after SARS-CoV-2 infection, present for at least 3 months as a continuous, relapsing and remitting, or progressive disease state.
• The condition can affect multiple organ systems and manifest with various symptoms and diagnosable conditions.
• Long COVID can follow asymptomatic, mild, or severe SARS-CoV-2 infection, with recognized or unrecognized previous infections.
• It can be continuous from acute infection or have a delayed onset weeks or months after apparent recovery.
• The condition affects both children and adults, regardless of health status, demographics, or socioeconomic factors.
• Long COVID can exacerbate preexisting health conditions or present as new conditions.
• Severity ranges from mild to severe, with potential resolution over months or persistence for years.
• Diagnosis is primarily clinical, as no definitive biomarker currently exists.
• The condition can significantly impair patients’ ability to work, attend school, and perform daily activities.
• The 2024 NASEM definition adopts the patient-coined term “Long COVID” for consistency and clarity.
• The definition situates long COVID among a larger class of infection-associated chronic conditions.
• Unlike some previous definitions, the NASEM definition does not require proof of previous SARS-CoV-2 infection.
• The definition includes a list of characteristic symptoms and associated diagnosable conditions.
• Clinical judgment is crucial in assessing patients for possible long COVID, considering both exacerbation of existing conditions and new-onset diseases.
• The definition’s inclusivity may lead to high diagnostic sensitivity but lower specificity, necessitating careful clinical consideration.
• Risk factors for long COVID include female sex, repeated infection, and more severe initial infection.
• The NASEM committee recommends revisiting the definition within 3 years based on emerging scientific knowledge.

According to the results of a study published in Vaccines (Basel), the odds ratios (OR) analyses based on observed data showed that, compared to no vaccination, bivalent vaccination was associated with a 41% reduced risk of long COVID expressed as ≥3 symptoms and with a 43% reduced risk of long COVID expressed as ≥2 symptoms.

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