ICD-10 code B34 is defined by the World Health Organization as a viral infection of unspecified site, serving as the official classification entry for viral infections lacking a more precise anatomical or etiological designation [1]. As a classification entity, B34 is bounded in scope to situations in which a viral cause is identified but the affected site is not documented or does not map to a more specific ICD-10 category [1].
Disease overview
Viral infection of unspecified site
未指定部位的病毒感染
Evidence-backed informationEN 1/5 applicable sections · ZH 1/5 applicable sectionsUpdated Sep 3, 2026
Viral infection of unspecified site corresponds to ICD-10 code B34, a residual classification category used when a viral etiology is established but the anatomical site of infection is not otherwise specified [1]. Within ICD-10, B34 functions as a nosological placeholder rather than a discrete clinical entity, capturing viral diagnoses that cannot be assigned to a more specific code [1]. Its public-health utility lies primarily in aggregated coding and surveillance, where it signals the presence of unspecified viral diagnoses within routinely collected health data [1].
Read the full clinical and epidemiological profile2
- 1WHO ICD-10. ICD-10 B34: Viral infection of unspecified site [Internet]. cited 3 Sept 2026.Available from: https://icd.who.int/browse10/2019/en#/B34
- B34
Data access
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