Specifically, these populations include people who are:

Born in countries where the prevalence of hepatitis B is high (defined as ≥2% of the population), whether or not they have been vaccinated
Born in the United States whose parents are from countries where the prevalence of hepatitis B is very high (defined as ≥8% of the population), and who were not vaccinated
HIV positive
Intravenous drug users
Men who have sex with men
In close contact with (i.e. live or have sex with) people known to have hepatitis B
Pregnant
Beginning immunosuppressive or cytotoxic therapy
Found to have elevated liver enzymes without a known cause
Blood, organ, or tissue donors
Incarcerated
On hemodialysisScreening consists of a blood test that detects hepatitis B surface antigen (HBsAg). If HBsAg is present, a second test – usually done on the same blood sample – that detects the antibody for the hepatitis B core antigen (anti-HBcAg) can differentiate between acute and chronic infection. People who are high-risk whose blood tests negative for HBsAg can receive the hepatitis B vaccine to prevent future infection. Hepatitis C
The CDC, WHO, USPSTF, AASLD, and ACOG recommend screening people at high risk for hepatitis C infection.
Preadolescents generally prefer certain brands, and are a heavily targeted market of many advertisers. Their tendency to buy brand-name items may be due to a desire to fit in, although the desire is not as strong as it is with teenagers. Some scholars suggest that pre-adolescents ... reported frequent encounters with sexual material in the media, valued the information received from it, and used it as a learning resource ... and evaluated such content through what they perceived to be sexual morality. However, other research has suggested that sexual media influences on preadolescent and adolescent sexual behavior is minimal. Freud
Freud called this stage the latency period to indicate that sexual feelings and interest went underground. Erik H. Erikson noted that latency period children in middle childhood can then direct more of their energy into asexual pursuits such as school, athletics, and same-sex friendships. Nevertheless, recent research contradicts these notions—suggesting that sexual development, interest, and behavior among latent period children does not cease. Instead, the apparent lack of sexual interest is due to children not sharing their sexual interests/emotions with adults. See also
Precocious puberty

References
Further reading
 The dictionary definition of Wikisaurus:preteen at Wiktionary
Myers, James. "Tweens and cool", Admap, March 2004. G. Berry Brazelton, Heart Start: The Emotional Foundations of School Readiness (Arlington 1992)