Killed vs. Modified-Live Vaccines

Introduction

For some antigens, veterinarians have to decide whether to use a killed vaccine or a modified-live vaccine. Each vaccine has its advantages, and each has its disadvantages. Most killed vaccines contain an adjuvant system, whose purpose is to stimulate an immune response. Without an adjuvant, the body is less likely to produce an effective response to the disease antigen. This discussion will cover the differences between killed and modified-live vaccines.

Commentary

In order to make an informed decision regarding killed and modified-live vaccines, it is important to know the generally accepted characteristics of each type of vaccine advantage and disadvantage.

Killed Vaccine
Advantages Disadvantages
No reversion to virulence Two doses often needed for initial response
Safe in pregnant animals
Safe in immunocompromised animals
No shedding of the virus
Modified-live Vaccine
Advantages Disadvantages
Less frequent transient adverse responses than killed vaccine Higher potential for vaccine-induced disease
Parenteral or mucosal administration Vaccinal virus shed

Viral replication implies:
  • Possible risk in pregnant animals
  • Possible risk in immunocompromised animals

Short shelf life when reconstituted

Easily inactivated by mishandling
Summary of Vaccine Antigen Presentations

FDAH Pfizer Merial Schering-Plough Intervet
Distemper MLV MLV R MLV MLV
Parvo MLV MLV MLV MLV MLV
Adenovirus MLV MLV MLV MLV MLV
Parainfluenza MLV MLV MLV MLV MLV
Corona K-A K-A MLV K-A K-A
Lepto K-A K-A K-A K-A K-A
Lyme K-A K-A R K-A K-A
Panleukopenia K-A & MLV MLV MLV MLV MLV
Calici K-A & MLV MLV MLV MLV MLV
Herpes K-A & MLV MLV MLV MLV MLV
Chlamydia K-A MLV MLV MLV MLV
Leukemia K-A K-A K-NA K-A K-NA
Rabies K-A K-A K-A & R K-A K-A
Key
MLVModified-live
K-AKilled adjuvanted
K-NAKilled with no adjuvant
RRecombinant

Studies

Adjuvants

Vaccine adjuvants are chemical proteins that enhance the immune response to vaccine antigens. more

AVMA Position

The AVMA Council on Biologic and Therapeutic Agents (COBTA) has thoroughly reviewed information on dog and cat vaccines and has issued two reports: 1. Principles of Vaccination - JAVMA Sept. 1, 2001 2.Report on Cat and Dog Vaccines - JAVMA Nov. 15, 2002 more

AAHA Canine Vaccination Guidelines

Limited published scientific information exists on duration of immunity. Therefore, these guidelines and recommendations are based on limited scientific evidence but are supported by consensus and expert opinion, as well as clinical evidence.more

AAFP Feline Vaccination Guidelines

Extended vaccination intervals recommended in the 2000 Report of the American Association of Feline Practitioners (AAFP) and Academy of Feline Medicine Advisory Panel on Feline Vaccines referenced a foundation study conducted by Dr. Fred Scott. more

Killed vs. Modified-Live Vaccines

For some antigens, veterinarians have to decide whether to use a killed vaccine or a modified-live vaccine. Each vaccine has its advantages, and each has its disadvantages. more

Recent Information: Three-Year Duration of Immunity Challenge Studies

Fort Dodge completed a long-term vaccination challenge study to determine if three main canine antigens,canine distemper virus (CDV),canine adenovirus type 2 (CAV-2) and canine parvovirus (CPV),protected for three years. more

Sarcomas

In 1996, the Vaccine Associated Feline Sarcoma Task Force was formed with the mission of determining the cause of sarcomas in cats. more

The Important Role of Vaccine Adjuvants

Adjuvants are agents designed to stimulate the immune response to vaccine antigens. more

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