Yes! The summit X3 seat when fully reclined has been approved for strolling with your baby from birth - alternatively with the capsule or bassinet sold separately.
Running with your baby:
Do not run/jog with children under 6 months of age in the stroller seat or if using a car seat with the Baby Jogger Car Seat Adaptor. Always check with your child's pediatrician before running/jogging with your child.