CDC Director Dr. Rochelle Walensky said earlier this month that hospitals are seeing more younger adults admitted with Covid-19 as more contagious variants spread. Older teens and young adults were among the last prioritized to get the coronavirus vaccines and many of them have yet to receive the shots. Young adults are also thought to be involved in more high-risk behaviors such as playing close-contact sports and going out to bars. Those factors coupled with the highly contagious B.1.1.7 variant are likely driving a surge in young people going to the hospital, health experts say.