Error in Self.vaccination.append(vaccine)

class Patient(object):
    ''' This is something which I forgot '''

    # status = "patient"
    def __init__(self, name, age):
        self.name = name
        self.age = age
        self.conditions = []
    def get_details(self):
        print(f"Patient Record: {self.name} ,{self.age} Years Current Information: {self.conditions}.")

    def add_info(self, information):
        self.conditions.append(information)


class Infant(Patient):
    # vaccination =[]    -- Without this throwing error but not in lecture tutorial

    def __int__(self, name, age):
        self.vaccination = []
        super().__init__(name, age)

    def add_vac(self, vaccine):
        self.vaccination.append(vaccine)

    def get_details(self):
        print(f"Patient record: {self.name},{self.age} "
              f"Patient condition: {self.conditions} "
              f"Patient has had {self.vaccination} "
              f"\n{self.name} is an infant, has he had all his checks?")

archie = Infant("archie", 4)
archie.add_vac("NMR")
archie.get_details()

Traceback (most recent call last):
  File "C:\Users\ASUS\PycharmProjects\Python365\Worksheet1.py", line 301, in <module>
    archie.add_vac("NMR")
  File "C:\Users\ASUS\PycharmProjects\Python365\Worksheet1.py", line 291, in add_vac
    self.vaccination.append(vaccine)
AttributeError: 'Infant' object has no attribute 'vaccination'

Both code and the error attached code seems identical with Gliss notebook but getting an error (solution I knew too i.e declaring Vaccine variable on Class level
but why??)