Teenagers' demand for mental health care skyrocketed last year amid the pandemic, even as their overall need for care declined, according to a new analysis by FAIR Health.

Why it matters: Parents, schools and pediatricians have been warning for months that kids aren't OK, and this analysis backs up their concern with numbers.

The big picture: The coronavirus pandemic has been disruptive to the lives of Americans of all ages, but for teenagers, the isolation and change in routine comes during a critical developmental stage.

• The toll that staying home has taken on children's mental health is one of many reasons schools should reopen, some experts say.

By the numbers: Mental health care claim lines — or individual health services — for children 13-18 doubled in March and April of last year, compared to 2019.

• In contrast, the number of overall claim lines for this age group was about half of the 2019 level.
• This trend continued on through November, although less drastically.

Details: Females were much likelier to require mental health care than males.

• The percentage of all medical claim lines that were for intentional self-harm nearly doubled in March and April, compared to the same month in 2019. Claim lines for overdoses increased by 94.91% in March and 119.31% in April compared to the year before. Both remained elevated through November.
• The most common diagnoses in teenagers were consistently major depressive disorder, generalized anxiety disorder and adjustment disorders. These conditions also became more prevalent, as a percentage of total medical claim lines, compared to 2019 levels.

What we're watching: Mental health issues can be situational, but that doesn't mean that once the pandemic ends, all will go back to normal.

• Some children will likely require long-term treatment, something the U.S. health system has historically been bad at.