Vaccines have come a long way since 1022 A.D., when a Buddhist nun fashioned what many consider the precursor to vaccines in an effort to fight smallpox. Since then, vaccines have stopped smallpox virus, are close to eradicating the polio virus and have slowed numerous other disease-causing microbes. Where are they headed? Today, scientists and vaccine manufacturers are aiming the next wave of vaccines at a group considered the least likely to receive preventive care and most likely to exhibit risk-taking behavior-adolescents. Experts in adolescent health see vaccines as effective tools for disease prevention. "Despite strong recommendations from organizations such as the American Medical Association and the American Academy of Pediatrics, 35 million adolescents fail to receive at least one recommended vaccine," said AMA President J. Edward Hill, M.D. "When adolescents do not receive recommended immunizations, they become vulnerable to diseases that can cause serious illness and even death." Currently, the CDC immunization schedule for adolescents includes: • Standard tetanus-diphtheria-acellular pertussis booster (Pertussis booster recommendation added June 2005); • Hepatitis B series and the varicella (chickenpox) vaccine for those who missed out as younger children; • Second MMR shot if not already given; • Meningococcal conjugate or polysaccharide vaccine, depending on age and circumstance; • Influenza, hepatitis A and pneumococcal polysaccharide vaccines for some adolescents. Vaccines making their way from the research bench, through clinical trials and, finally, the approval process, will in the next few years protect against such diseases as: • Human papillomaviruses: cancer-causing viruses that infect nearly 3 out of 4 Americans between the ages of 15 and 49; • Chlamydia: one of the most widespread bacterial STIs in America, with three million infections annually; • HIV: the virus that causes AIDS (Acquired Immunodeficiency Syndrome), characterized by a weakened immune system causing susceptibility to infections and cancers; • Herpes simplex virus 2: a virus infecting 40 to 60 million Americans, with half a million new infections every year; • Staphylococcus aureus: common bacteria found in the nose or on the skin of healthy people, which can sometimes cause serious infections. Today's scientists envision a time when vaccines may defeat cancers, prevent the common cold and perhaps even drug abuse.