What is a Lapsed Vaccination
A lapsed vaccination occurs when a pet misses a booster or does not complete the recommended vaccination schedule. Without timely boosters or a full course, your pet may lose protection against serious and potentially life-threatening diseases.
Written by Dr. Mariella Roberts, Veterinary Surgeon, Animal Trust Vets CIC | Published October 2025 | Review date October 2028 | This advice is for UK pets only and is not a replacement for seeing a vet
When does a lapsed vaccination happen
A vaccination is typically considered lapsed if a booster is missed by more than three months after the due date. While some immunity may still be present shortly after the missed booster, the World Small Animal Veterinary Association (WSAVA) advises that beyond this three-month window, pets may no longer be adequately protected. In most cases, the full vaccination course will need to be restarted.
Why is a lapsed vaccination important to address?
Keeping vaccinations up to date is essential for your pet’s health, preventing serious and potentially fatal diseases. Lapsed vaccinations increase the risk of your pet contracting and spreading preventable diseases, some of which can affect humans too.
Regular vaccinations also help avoid costly treatments and hospital stays that may result from preventable illnesses. See our vaccine guide.