Vaccination is the administration of antigen but is relatively harmless. Antigenic components in vaccinated individuals can produce protective immunity against the specific infectious agent. Vaccination is a highly effective method of preventing certain infectious diseases.
Vaccines are generally very safe, serious adverse reactions are uncommon. Routine immunization programs protect from number of infectious diseases that previously caused millions of deaths per year, but sometime vaccination failure occur that lead to mortality.
Vaccination failure occurs when an animal fails to develop an adequate immune response that is sufficient to protect that animal from disease following vaccine administration. However, many times it’s not the fault of the vaccine, but rather the circumstances, surrounding and the vaccination process may cause vaccine failure. Vaccination failure can occur for many reasons.
There are 2 major factors responsible for vaccine failures, the first one is vaccine-related like failures in vaccine attenuation, vaccination management or administration. The other is host-related, which includes age, genetics, immune status, health or nutritional status may lead to primary or secondary vaccination failures. However, satisfactory vaccines have not yet been developed against several of the most life-threatening conditions.
Specific vaccine for specific strain/disease:
Select vaccine according to class of animals, the stage of production, and the disease against which you are trying to protect. A vaccine must contain an antigen made from a specific disease-causing organism. Furthermore, some disease-causing organisms may have several strains or serotypes, and vaccines may not be cross-protective for all types and strains.
To choose proper antigen, select high quality vaccines that have been proven to be safe and effective. Avoid buying the cheapest off-brand vaccine that may have low quality or contamination issues. Many diseases are caused by agents that consist of several different strains/serotypes.
For example, IBV and salmonella have more than 100 and 2000 recognized strains. FMD have 7 serotypes with no cross protection. In some cases, the vaccine may not contain the proper strains or serotypes of organism required to stimulate protective immunity against the specific causative agent.
Route of vaccination:
Restraining is essential for properly administration of any vaccine. Vaccines have been designed to work in specific sites under specific conditions. If a product is labeled for subcutaneous injection, it must be given subcutaneously. Any other route of administration, may lead to vaccination failure. Follow the label carefully and administer the product according to label.
Needle and syringe care is also important while vaccinating animals. While using a multiple or single dose syringe, inspect all parts and make sure it is cleaned. If you have to inject multiple vaccination, space them at least 4 inches apart. Never give more than 10cc of the vaccine at same site. Never mix two different vaccines in one syringe.
Storage of vaccines:
Vaccines are biological products that can be sensitive to environmental condition so storage of vaccine is very important. Always check the expiration date on the bottle and discard expired vaccine. Vaccine products must be kept at cold place and protect from direct sunlight. Keep a cooler on hand while transporting vaccine or working with cattle. While using modified-live virus products (MLV), use the entire bottle shortly after being reconstituted.
A good rule to follow, only mix enough product that you can use within an hour. Improper mixing of vaccine can also lead to failure due to difference in their pH value or diluent. While mixing vaccine, use transfer needles and avoid going into the bottle multiple times with needle, to decrease product contamination. If you are working with less number of animals, use smaller dose bottle first. Vaccine virus may become inactivated or denatured during storage or administration.
Maternally derived antibodies:
Maternal derived antibodies that calf receives from mother through colostrum can last for several months. During this time, vaccination may interfere with the calf’s ability to enhance his immune response and cause vaccination failure. So, most of vaccines are given after several months of age.
The exact timing of first vaccination can vary and often depend on other management practices such as branding or pregnancy checking, as well as depend upon immune status of the dam. Many weeks are required to an animal’s body to enhance immune response that provide full protection. Animals can get sick during that immunity building time, so we need to plan ahead. For calves, vaccinate several weeks prior to weaning in order to give them best protection during high risk period.
Stress decreases the immune response of animal. Therefore, we have to avoid vaccination during high periods of stress. In mature cows, we want to vaccinate with some of the reproductive antigens pre-breeding in order to give them the best protection prior to the breeding season. Don’t forget booster doses, especially in calves, or animals who are receiving a specific vaccine for the first time.
The first vaccine in young animal is meant to initiate the immune system, and the second vaccine gives it the boost of antigens it needs to provide a complete immune response. Otherwise it may lead to failure of vaccine. Vaccines do not ensure lifetime immunity, so annual or semi-annual boosters are also needed for mature animals. Administration of vaccine during fever or stress period may cause that disease in the animal due to low immune status.
Remember that no vaccine is 100% protective, and vaccination is the only part to prevent health program. A good vaccination program cannot overcome poor management. However, a well-designed, well timed and soundly executed vaccination program coupled with good management, nutrition and biosecurity will decrease the probability of disease problems and increase its genetic potential. Now a days, vaccination is very important to avoid economic loses. So, your herd veterinarian can help you to develop a comprehensive herd health management program to avoid vaccination failures.
The article is jointly written by Muhammad Hunain Ahmed, Muhammad Usman Naseer, Muhammad Haider Ali.
Student of M phil Pathology.