This is a randomized cross-sectional study of the Swedish population. Blood samples will be collected from a subpopulation in order to estimate the age specific sero-prevalence of the Swedish population for diseases included in the National Immunization Program (NIP), and to affirm the population's protection against polio. To be able to recommend complementary immunizations to immigrated children, a sub study focusing on foreign born teenagers will also be done and compared to children of the same age born in Sweden.

Besides the main objectives stated in the summary, the study consists of:

Vaccine related objectives:

• To estimate the seroprevalence regarding vaccine preventable diseases in the cohort of children about to enter adulthood (as a "receipt" of the vaccination program's functionality), and thereby form a basis for decision-making regarding recommendations about continuous vaccination in adult age
• To evaluate the concentration of antibodies that full-term newborns receive from their mothers, and to estimate plausible consequences to optimize the schedule of the NIP for each vaccine preventable disease
• To, in different age groups, evaluate changes over time and concentration of antibodies compared to a study conducted in 1997
• To evaluate plausible changes in the seroprevalence, for instance among children, related to an increased use of combined vaccines
• To document the age-specific seroprevalence against other diseases that will be vaccine preventable before start-up of new vaccination program
• To estimate the population seroprevalence against certain diseases against which vaccines have been developed during recent years and that might be introduced into the vaccination program within a couple of decades

Method:

• Adults: one blood sample of 10 mL blood from vein in arm from each individual
• Children: one blood sample of 5-10 mL blood from vein or capillary in arm from each individual
• Cord blood: one blood sample of 10 mL cord blood will be collected from each newborn in connection with childbirth

The objectives of the sub study are:

• To conduct the same type of analysis on foreign born 14-16 year olds as on 14-16 year olds being born in Sweden
• To also examine the immunity and infection situation with regard to Hepatitis B
• To conduct the corresponding examinations and priorities among the 14-16 year olds born in Sweden serving as control group

Inclusion Criteria:

• informed written consent (both groups)
• immigrated to Sweden after 6 years of age from a country with polio vaccination coverage < 85 % (Sub study group)
• living and attending school in Stockholm, Gothenburg or Malmoe (Sub study group)

Seroimmunity 2007: the Swedish population.

Sub study: foreign born children between 14-16 years of age.