California Code, Health and Safety Code - HSC § 1367.36

(a) A risk-based contract between a health care service plan and a physician or physician group that is issued, amended, delivered, or renewed in this state on or after January 1, 2001, shall not include a provision that requires a physician or a physician group to assume financial risk for the acquisition costs of required immunizations for children as a condition of accepting the risk-based contract. A physician or physician group shall not be required to assume financial risk for immunizations that are not part of the current contract.

(b) Beginning January 1, 2001, with respect to immunizations for children that are not part of the current contract between a health care service plan and a physician or physician group, the health care service plan shall reimburse a physician or physician group at the lowest of the following, until the contract is renegotiated: (1) the physician's actual acquisition cost, (2) the “average wholesale price” as published in the Drug Topics Red Book, or (3) the lowest acquisition cost through sources made available to the physician by the health care service plan. Reimbursements shall be made within 45 days of receipt by the plan of documents from the physician demonstrating that the immunizations were performed, consistent with Section 1371 or through an alternative funding mechanism mutually agreed to by the health care service plan and the physician or physician group. The alternative funding mechanism shall be based on reimbursements consistent with this subdivision.

(c) Physicians and physician groups may assume financial risk for providing required immunizations, if the immunizations have experiential data that has been negotiated and agreed upon by the health care service plan and the physician risk-bearing organization. However, a health care service plan shall not require a physician risk-bearing organization to accept financial risk or impose additional risk on a physician risk-bearing organization in violation of subdivision (a).

(d) A health care service plan shall not include the acquisition costs associated with required immunizations for children in the capitation rate of a physician who is individually capitated.