For minor illnesses, visit the SSM Health Express Clinic in Fenton, Missouri. This location is conveniently located off Smizer Mill Road. Walk in or schedule an appointment online and avoid the wait. SSM Health Express Clinic treats patients 12 months and up. We offer symptomatic and asymptomatic COVID-19 testing. Patients with flu or COVID-19-like symptoms should wait in their vehicle and call the number posted on the designated parking spots upon arrival.