A combination hepatitis A/typhoid (ViCPS) vaccine, administered as a single dose, confers high levels of protection against both these diseases. It will provide at least 6 month protection against hepatitis A. A healthy adult received this vaccination 4 months ago, and antibodies against hepatitis A were detected for the first time at the level of 10 mg per ml serum 10 days after the vaccine was administrated. One month after the vaccine was administrated, the antibody concentration dropped to 0.1 mg per ml serum. This individual is now exposed to hepatitis A virus (the virus causes hepatitis A). With unchanged overall health condition of this individual, for the earliest, within what timeframe will it be possible to detect antibodies against hepatitis A at the level of 10 mg per ml serum (counting from the day of exposure)? (Comparing to the timeframe when the vaccine was administrated). And why?