In any case where the medical examiner, or physician acting as such, or the agent of the insurer recording the answers of the applicant where a medical examination is waived, of any insurance company doing business in this State, shall issue a certificate of health, or declare the applicant a fit subject for insurance, or so report to the company or its agent under the rules and regulations of the company, it shall thereby be estopped from setting up in defense of the action on the policy or certificate issued to the insured, that the insured was not in the condition of health required by the policy or certificate or by the company issuing the same at the time of the medical examination, or the recording of the answers of the applicant where a medical examination is waived, unless the same was procured by or through the fraud, deceit, or misrepresentation of or on behalf of the insured.