After spending much of the past year tending to elderly patients, doctors are seeing a clear demographic shift: young and middle-aged adults make up a growing share of the patients in COVID-19 hospital wards. … Nationally, adults under 50 now account for the most hospitalized COVID-19 patients in the country — about 35% of all hospital admissions. Those age 50 to 64 account for the second-highest number of hospitalizations, or about 31%. Meanwhile, hospitalizations among adults over 65 have fallen significantly.