Viruses can strike one group more severely than another. The 1918 flu, which claimed 50 million lives worldwide, particularly affected young adults. The Zika outbreak that raged through Brazil in 2015-2016 had an especially devastating effect on pregnant women, attacking the brains of the fetuses they carried.
COVID-19, the disease caused by the new coronavirus that originated in China, appears to get more dangerous with age, says Michael Mina, MD, PhD, an assistant professor of epidemiology at the Harvard T.H. Chan School of Public Health.