>>144859, >>144860

[CDC]
Oral polio vaccine (OPV) contains attenuated (weakened) polioviruses

Available vaccines
There are two types of vaccines that protect against polio.
Inactivated polio vaccine (IPV)
The only polio vaccine that has been used in the United States since 2000.
It is given by shot in the leg or arm, depending on the patient's age.
Oral polio vaccine (OPV)
No longer licensed or available in the United States
It is still used in many parts of the world.
Children receive doses of the vaccine by drops in the mouth.
Since 2000, only IPV has been used to eliminate the risk of polio variants that can occur with OPV.
https://www.cdc.gov/polio/vaccines/index.html