Section 4BB. Any subscription certificate under an individual or group medical service agreement, except certificates that provide stand-alone dental services, that is delivered or issued or renewed in the commonwealth, shall provide, as benefits to all individual subscribers and members within the commonwealth and to all group members having a principal place of employment within the commonwealth, coverage to persons under 26 years of age or for 2 years after the end of the calendar year in which such persons last qualified as dependents under 26 U.S.C. 106, whichever occurs first.