thank you to sheryl crow, and for spending your earth day morning with us.enture out on roosevelt island, bill nye the science guy is riding shotgun with al. we will catch up with them in just a few. >>> let's get right to the news at 8:00. the marathon effort to vaccinate americans against covid has hit a milestone and maybe even a wall. 200 million shots have been given, but nearly half of the adult population has not yet been vaccinated and many by choice. nbc national correspondent miguel almaguer joins us now with the very latest. hey, miguel, good morning. >> reporter: good morning, the biden administration reached that goal of 200 million shots in just under 100 days. it means more than half of all adults in this country have received at least one shot as the focus now turns to many who may be hesitant. to help speed up inoculations the president is calling on all employers to give employees paid time off to get vaccinated or if they're feeling side effects after vaccination, but the race to reach herd immunity could be stalled by those who simply don