Basic immunization,
Basic immunization strategies and schedules The decision to immunize at a particular age is, for the most part, a compromise between: The desire to immunize as early as possible, thereby protecting the child before he/she becomes exposed to the infectious agent, and The requirement to wait both for the infant's immune response to mature and for the maternally-derived antibodies that crossed the placenta pre-natally to disappear, so that the immunization will be effective. Vaccines are recommended for the youngest age group at risk for developing the disease whose members are known to develop an adequate response to immunization without adverse effects from the vaccine. The basic schedule calls for all children to receive 1 dose of BCG vaccine, 3 doses of DTP vaccine, 4 doses of OPV, and 1 dose of measles vaccine before their first birthday. In countries where HBsAg carriage rates are >2%, universal infant vaccination with Hep B vaccine is recommended. Where HBsA