Shift in Viral Strains of Hepatitis B in Stockholm as Reflected by Subtypes of Hepatitis B Antigen

Subtypes of hepatitis B antigen (HBAg) were determined in cases of acute hepatitis hospitalized in Stockholm 1953–54 and 1970. The relative incidence of HBAg-positive patients was similar in the two materials (43 and 49%). In 1953–54 subtype ad was found in 22 out of 31 HBAg-positive patients; subtype ay in 2 patients only. In 1970 only 12 out of the 99 HBAg-positive patients had the ad subtype, while 75 had the ay subtype. All 18 drug addicts among the HBAg-positive patients from 1970 carried the ay subtype and so did 90 out of 95 HBAg-positive drug addicts attending the outpatient department during the years of 1971–1972. Obviously a shift in predominating subtype has taken place from ad in 1953–54 to ay in 1970.