Heard the flu vaccine fluvirin is not approved for use with small children?

Yes. This weakened virus vaccine actually uses a low grade lung inflammation to enter the circulation and begin triggering an antibody response. In younger kids, people with asthma & a few others, the risk of triggering a bronchitis or asthma attack makes it unsuitable for these populations.It is also never given when other live virus vaccines are avoided.
Fluvirin. Yes you are right Fluvirin is approved for for persons 4 years of age and older.It is not indicated for children less than 4 years old.