The study described here will immunize children with trivalent influenza vaccine (TIV) and determine whether this reduces influenza illness among the immunized children and their older family members. The comparison or control group for the children receiving influenza vaccine will be children immunized with inactivated poliovirus vaccine (IPV). The study will also provide information on the amount of disease produced by influenza in the study population.

Influenza is an important cause of illness among children and adults in the United States. Influenza is likely also an important cause of illness in India, but published data on influenza infections in India are limited, especially for children. Although influenza vaccines are used routinely in the United States, including in young children, influenza vaccines have not seen widespread use in India. This is likely due to the lack of information from India about disease burden due to influenza and because the influenza vaccines have never been tested for efficacy in India. In addition, because young children are thought to be important in the spread of influenza in families, it is possible immunization of children against influenza will reduce influenza infections among older children and adults in the home.

Inclusion Criteria:

• Inclusion in either vaccine group (TIV or IPV) will require ages 6 months through 10 years of age.
• All individuals in enrolled households will be eligible for enrollment into surveillance arm.

Exclusion Criteria:

• Exclusion criteria from the vaccine groups includes known allergy to eggs, or hypersensitivity to other components of a vaccine (streptomycin, neomycin, and polymyxin B)