More than four in 10 U.S. high school students say they have been feeling sad or hopeless during the pandemic, according to government survey results released Thursday.

Some medical groups have warned that the isolation of the pandemic with school closures and a lack of social gatherings is already taking a toll on young people’s mental health.

“This really gives us evidence that it’s safe to say that this pandemic is taking an incredible toll on young people and their families,” said Catherine Etiler of the Centers for Disease Control and Prevention.

The reports are based on an anonymous online survey of about 7,700 public and private high school students from 128 schools during the first six months of 2021. It is based on a similar survey conducted by the CDC in schools every other year,

Among the findings:

— 44% said they had been sad about hopelessness in the past year. A similar survey before the advent of COVID-19 put the figure at 37%.

— 66% said they found it more difficult to finish school.

— 29% said a parent or other adult in their home lost their job, and 11% said they experienced physical abuse by a parent or other adult in their home.

— 24% said they went hungry during the pandemic because they didn’t have enough food at home.

There may be some underreporting, especially for certain questions about family emotional or physical abuse. Teens may be afraid of abusive parents or other adults who might see their reactions, said Ilan Cerna-Turoff, a researcher at Columbia University who studies children’s mental health.

CDC officials say the epidemic does not affect teens equally. LGBT youth report poorer mental health and more suicide attempts than others. About 75% said they had experienced emotional abuse at home, and 20% said they had been physically abused. In contrast, half of heterosexual students reported emotional abuse and 10 percent reported physical abuse, the CDC said.

The Associated Press Health and Science Division was supported by the Howard Hughes Medical Institute Division of Science Education. The Associated Press is solely responsible for all content.