A majority of counties across the U.S. are seeing a steady rise in vaccine exemptions for religious or personal beliefs among children entering kindergarten, a trend that has accelerated since the pandemic, according to a new study. The research, published Wednesday in JAMA , is based on a data investigation by NBC News with Stanford University. Mustafa Fattah, medical fellow with NBC News, is lead author on the study. The researchers analyzed data on medical and nonmedical vaccine exemptions