API:  http://id.who.int/icd/release/10/2019/U09
{
    "@context": "http://id.who.int/icd/contexts/contextForICD10Entity.json",
    "@id": "http://id.who.int/icd/release/10/2019/U09",
    "parent": [
        "http://id.who.int/icd/release/10/2019/U00-U49"
    ],
    "child": [
        "http://id.who.int/icd/release/10/2019/U09.9"
    ],
    "browserUrl": "http://apps.who.int/classifications/icd10/browse/2019/en#/U09",
    "code": "U09",
    "title": {
        "@language": "en",
        "@value": "Post COVID-19 condition"
    },
    "classKind": "category"
}
Title: Post COVID-19 condition
Code:  U09

Child

1.  http://id.who.int/icd/release/10/2019/U09.9