[The prevalence of antibody to hepatitis A virus in different age groups of Hokkaido inhabitants (author's transl)].

Serum specimens drawn at random from Hokkaido inhabitants were tested for antibody to the hepatitis A virus (anti-HAV) by radioimmunoassay. The prevalence in different age groups was as follows, cord blood and newborn infants 44.4%, under one year 0%, 1-9 years 5.3%, 10-19 years 0%, 20-29 years 9.1%, 30-39 years 80%, 40-49 years 90%, and over 50 years 100%. This survey confirmed that antibody against HAV could pass through placenta and HAV had been very common virus by the 1950's in Hokkaido.