This bill creates a new section in chapter 48.43 RCW that requires nongrandfathered group health plans issued or renewed on or after January 1, 2027 to cover prophylaxis, diagnosis, and treatment for "pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections" and "pediatric acute-onset neuropsychiatric syndrome." The coverage requirement is added as a new law provision to that chapter. The required coverage expressly includes antibiotics; medication and psychological and behavioral therapies to manage neuropsychiatric symptoms; immunomodulating medicines; plasma exchange; and intravenous immunoglobulin (IVIG) therapy. For IVIG, health carriers must cover three initial monthly immunomodulatory courses and may cover subsequent courses when the treating provider deems them medically necessary, provided (1) clinically appropriate trials of two less intensive treatments were not effective, were not tolerated, or did not produce sustained improvement as measured by a validated instrument directed at the patient's primary symptom complex, and (2) the treating provider recommends IVIG. Carriers may require clinical reevaluation at three-month intervals when providing IVIG under this subsection. The bill prohibits health carriers from denying or delaying coverage because the enrollee previously received treatment under a different diagnostic name, from limiting IVIG coverage in a way inconsistent with treatment guidelines developed by a referenced consortium, from requiring a trial of therapies that treat only neuropsychiatric symptoms before covering IVIG, from denying coverage for out-of-state treatment if a service is not available in state, and from denying coverage based on the patient's age. Small group health plans and health plans for public employees and their dependents under chapter 41.05 RCW are exempted. The text supplied does not define key terms used (for example, "nongrandfathered group health plans," "health carrier," or "small group health plans"), does not identify the "validated instrument" or the consortium that will develop guidelines, and does not include enforcement mechanisms, appeal processes, or penalties for noncompliance; it may depend on other statutory definitions or provisions not included in the provided excerpts.

If enacted, starting January 1, 2027 most employer group health plans that are not "grandfathered" will have to pay for diagnosing, preventing, and treating PANDAS and PANS, including antibiotics, psychiatric and behavioral therapies, immunomodulatory drugs, plasma exchange, and IVIG. Insurers must cover three initial monthly IVIG courses when a treating provider requests it and two less intensive treatments have failed or were not tolerated, may require clinical reevaluations every three months, and may not deny or delay coverage for reasons like prior treatment under a different diagnosis, patient age, or lack of in-state availability; small group plans and state public-employee plans are excluded. The direct impacts fall mainly on health carriers and employers sponsoring affected group plans, who should expect higher utilization and claim costs for expensive therapies such as IVIG and plasma exchange and therefore potential upward pressure on premiums or plan funding; patients and treating providers will likely gain easier access to these treatments when clinical criteria are met. Important implementation details are missing from the excerpt—terms like "nongrandfathered" plans, the consortium that will set IVIG guidelines, the validated instruments for measuring improvement, and enforcement or appeals procedures are not specified—so how coverage limits and clinical criteria are applied in practice remains uncertain.