As many as 80% of children in some states who received a first dose of H1N1 vaccine haven't received a booster dose that's necessary to fully protect them from swine flu, according to a USA TODAY review of immunization registry data from 10 states. State health officials are worried growing public complacency could put these children at risk if a third wave of disease hits this winter. Thousands of high risk kids missing 2nd H1N1 flu doses