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Serum specimens from 191 Finnish adults were tested for antibodies to hepatitis A virus (anti-HAV). The frequency of anti-HAV increased from 8% in the age group of 20-29 years to 92% in those older than 60 years. The level of 50% was reached between 40 and 50 years.
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Ukkonen et al. (1979) studied this question.
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