Fact check: Trump's claim about whether coronavirus affects young people

Trump's claim:

President Donald Trump "falsely claimed" at a Monday night campaign rally that the novel coronavirus "affects virtually nobody" younger than 18 and mainly threatens seniors and people with underlying health conditions, according to the Washington Post.

Fact check:

Trump contradicted himself. In a March interview with Washington Post associate editor Bob Woodward, he acknowledged that "plenty of young people" were affected and admitted that he'd downplayed the risks of the virus. It's not clear exactly which age group Trump was referring to when he said that, but here's what we know about how COVID-19 affects kids and young adults.

Since March, evidence has been building that young people aren't as impervious to coronavirus as initially thought. According to the CDC Covid Data tracker, a recent analysis of 143,273 deaths revealed that 843, about 0.6%, occurred in people younger than 30, while 88, about 0.06%, occurred in people younger than 18.

In a recent MMWR report on COVID-19-related deaths in persons under 21, Centers for Disease Control and Prevention researchers showed that that nearly three quarters of SARS-CoV-2-associated deaths among infants, children, adolescents and young adults have occurred in persons aged 10 to 20 years, with a disproportionate percentage among those aged 18 to 20 years and among Hispanics, Blacks, American Indians and persons with underlying medical conditions.

Young adults also are at risk for severe complications of COVID-19. A recent JAMA Internal Medicine study of roughly 3,200 people ages 18 to 34 showed that 684 people, about 21%, required intensive care and 331, about 10%, required ventilators. Ninety people, about 3%, died.

The rates of poor outcomes in this population were lower than those reported for older adults with COVID-19, but higher than the rates reported for other diseases in young adults. For example, the death rate the authors found for COVID-19 in young adults is more than twice the death rate for heart attacks in the same age group. Morbid obesity, high blood pressure and diabetes were associated with greater risks of serious complications in this age group, which is similar to what we see in older adults. In fact, young adults with more than one of these conditions faces risks comparable to those observed in middle-aged adults without them.

In children and adults of all ages, pre-existing medical conditions undoubtedly increase the risk for severe complications and death from COVID-19. It's important to note that the cause of death in these individuals is COVID-19, not their underlying disease or old age.

Leah Croll, M.D., a neurology resident at NYU Langone Health, is a contributor to the ABC News Medical Unit.