Katavac CHP Dosage and administration The vaccine is to be administered subcutaneously to cats of 9 weeks of age or older. Aseptically reconstitute the contents of the freeze-dried vial using 1 ml sterile diluent or Fevaxyn FeLV as a diluent. Primary vaccination: A single dose of Katavac CHP should be administered from 9 weeks of age followed by a second injection after an interval of 3-4 weeks. Booster vaccination: Booster vaccinations are recommended every 12 months. Field experience indicates that a single vaccination can be expected to be sufficient as an annual booster.