Can cases cut down on exposure?

Greetings, Edora8.

We see that you reached out to us from About potential magnetic interference with medical devices.

Per that resource: 

“Magnetic interference and medical devicesUnder certain conditions, magnets and electromagnetic fields might interfere with medical devices. For example, implanted pacemakers and defibrillators might contain sensors that respond to magnets and radios when in close contact. To avoid any potential interactions with these types of medical devices, keep your Apple product a safe distance away from your medical device (more than 6 inches / 15 cm apart or more than 12 inches / 30 cm apart if wirelessly charging). Consult with your physician and your device manufacturer for specific guidelines.If you suspect that your Apple product is interfering with your medical device, stop using your Apple product and consult your physician and your medical-device manufacturer.”

If you have question above what the resource offers, please Contact Apple Support.

We hope this helps! 

Sincerely.