Subject to § 58-18-20, every blanket health insurance policy shall contain a provision that written notice of sickness or of injury must be given to the insurer within thirty days after the date when such sickness or injury occurred. Failure to give notice within such time shall not invalidate nor reduce any claim if it shall be shown not to have been reasonably possible to give such notice and that notice was given as soon as was reasonably possible.
SDCL 58-18-22