A total of 51 children between the ages of 4 and 9 will be randomized to receive a two dose schedule of either licensed live attenuated A/California/07/09 influenza vaccine (LAIV) or licensed inactivated A/California/07/09 influenza vaccine (IIV) or IIV followed by LAIV separated by 28 days. Children with prior vaccination or natural infection with novel H1N1 influenza will be excluded. Randomization will be stratified by pre-existing HAI titers to the previous winter's seasonal H1N1 A/Brisbane/57/07 reference virus.