CHICAGO (CBS) — The severe flu outbreak gripping Chicago and the rest of the country has doctors urging everyone to get their flu shot. One problem: some local parents are now finding out flu shots are in short supply.

Some pharmacies across the region are experiencing a shortage of Tamiflu, a prescription medicine used to treat influenza, as well as test kits and flu vaccines.

“We have been out [of flu vaccines] for the last three weeks, and we have not been able to receive any from our vendor,” Dr. Kenneth Polin said, who’s with Lurie Children’s Primary Care – Town & Country Pediatrics. “Our patients are frustrated.”

LCPC Town & Country Pediatrics have enough vaccines for the younger kids, but not for anyone over the age of 3.

Dr. Polin says local pharmacy clinics are an option, although CVS says some may be out of stock. The drugstore said there is not a “widespread shortage,” rather an “increased demand.”