In what is being described as the largest-ever cyberattack on the U.S. health care system, a major operator of multiple services critical to payer authorization, coverage, prescriptions, and provider payment has been effectively shut down since Feb. 21. Change Healthcare, the UnitedHealth Group subsidiary that suffered the ransomware attack, hasn't yet announced when it would return to full functionality, but its parent company is offering some workarounds in the meantime and has given APTA resources for members to use to request assistance and process claims.