Vaccination is something every cat should do after birth to prevent some serious infectious diseases. However, vaccines are also weakened viruses that stimulate the production of antibodies in cats. Therefore, if a cat's immune system is abnormal, vaccination can have the opposite effect. So, after a cat is born, you should observe its condition first, and only healthy cats should be vaccinated. 
Generally, healthy kittens can be vaccinated about a week after successful weaning. However, if it's a newly acquired kitten, it's best to take it to the vet for a checkup and vaccinations before bringing it home. During the checkup, the veterinarian will perform a health examination, provide a written health certificate, and inquire about the kitten's behavior.
At the same time, there are contraindications for vaccinating cats. The animal's age, health condition, physical condition, and nutritional status must be considered when administering a vaccine.
Do not bathe your cat for a week before vaccination. Have your veterinarian take your cat's temperature before the vaccination to ensure they are healthy. Do not bathe your cat after the vaccination to ensure the first year's immunization schedule is completed. Closely observe your cat's behavior, appetite, and bowel movements after each vaccination for any changes.
Generally, before vaccination, a veterinarian should perform a clinical examination on the cat, including checking its temperature, respiration, heart rate, physical examination, and medical history. A normal kitten's temperature is 38–38.5°C, and an adult cat's is around 38°C, but neither should exceed 38.7°C, unless the cat has just come out of a hot car, in which case its temperature may be slightly higher. The physical examination mainly observes for eye discharge and nasal discharge, abnormal color of the oral mucosa, proliferative blood vessels in the conjunctiva, vomiting, loss of appetite, diarrhea, a history of infectious diseases, and whether the cat has been in contact with sick cats.
In general, the following types of cats are not suitable for vaccination:
1. Generally, cats under eight weeks of age should not be vaccinated. For very young pets, maternal antibody interference should be considered, and vaccination should be performed according to the vaccine instructions. By twelve weeks of age, maternal antibodies in cats generally have decreased to non-interfering levels. For most infectious diseases, the final vaccination should be given at twelve weeks of age or slightly later to provide protection. Older cats, although they may have various antibodies, may have lower titers that are insufficient to protect against disease and still need to be vaccinated according to the immunization schedule.
Second, cats with poor physical condition or malnutrition should not be vaccinated.
Third, cats should not be vaccinated when they are sick. Vaccination at this time may worsen the condition due to vaccine reactions.
IV. Live attenuated vaccines are generally not suitable for pregnant cats due to their potentially strong adverse reactions. In particular, pregnant cats should not be vaccinated against feline panleukopenia (feline distemper), as this vaccine can cross the placental barrier and infect the fetus, leading to stillbirth, miscarriage, premature birth, or birth of a fetus with cerebellar malformation. If a pregnant cat needs to be vaccinated, an inactivated vaccine should be administered.
Newly purchased cats should be taken to a veterinary hospital for examination or quarantined for seven days to ensure they are healthy before vaccination. Cats need to be vaccinated against rabies when they are three months old. The chance of a cat getting rabies is small, but once it does, the mortality rate is 100%.
