This randomized clinical phase III trial studies how well web-based physical activity intervention works in improving long term health in children and adolescents with cancer. Regular physical activity after receiving treatment for cancer may help to maintain a healthy weight and improve energy levels and overall health.

This study evaluates immunologic response following COVID-19 vaccination in children, adolescents, and young adults with cancer. Vaccines work by stimulating the bodys immune cells to respond against a specific disease. The immune response produces protection from that disease. Effects from cancer and from treatments for cancer can reduce the bodys natural disease fighting ability (called immunity). Factors such as vaccine type, timing of vaccine dosing related to treatment for cancer and number of vaccine doses or boosts (extra vaccine shots) may strengthen or diminish the bodys protective immune response. This study may help researchers learn more about how the bodys immune system responds to the COVID-19 vaccine when the vaccination is given during or after cancer treatment.