(1) Except as provided in subsection (2) of this section, child day care centers and outdoor nature-based child care providers licensed under this chapter may not allow on the premises an employee or volunteer, who has not provided the child day care center or outdoor nature-based child care provider with:

(a) Immunization records indicating that he or she has received the measles, mumps, and rubella vaccine; or

(b) Proof of immunity from measles through documentation of laboratory evidence of antibody titer or a health care provider's attestation of the person's history of measles sufficient to provide immunity against measles.

(2)(a) The child day care center and outdoor nature-based child care provider may allow a person to be employed or volunteer on the premises for up to thirty calendar days if he or she signs a written attestation that he or she has received the measles, mumps, and rubella vaccine or is immune from measles, but requires additional time to obtain and provide the records required in subsection (1)(a) or (b) of this section.

(b) The child day care center and outdoor nature-based child care provider may allow a person to be employed or volunteer on the premises if the person provides the child day care center or outdoor nature-based child care provider with a written certification signed by a health care practitioner, as defined in RCW 28A.210.090, that the measles, mumps, and rubella vaccine is, in the practitioner's judgment, not advisable for the person. This subsection (2)(b) does not apply if it is determined that the measles, mumps, and rubella vaccine is no longer contraindicated.

(3) The child day care center and outdoor nature-based child care provider shall maintain the documents required in subsection (1) or (2) of this section in the person's personnel record maintained by the child day care center.

(4) For purposes of this section, "volunteer" means a nonemployee who provides care and supervision to children at the child day care center or outdoor nature-based child care program.