What are the causes of animal immunization failure

After animals are vaccinated, if they cannot resist the invasion of the corresponding pathogen within the effective immunization period and still contract that infectious disease, or if the potency test fails, it can be considered immunization failure. There are many causes of immunization failure, and some common causes can be summarized into three major factors.

?I. Vaccine factors

1. The vaccine itself has poor protective performance or possesses a certain degree of virulence.

2. The serotype or subtype of the vaccine virus (bacterial) strain is inconsistent with the field epidemic virus (bacterial) strain, or the serotype of the epidemic strain has changed, or the vaccine was improperly selected or even the wrong vaccine was used.

3. Improper transportation or storage of the vaccine, or failure to use the vaccine promptly after dilution, resulting in vaccine inactivation or reduced potency, or the use of expired or deteriorated vaccines.

4. Interference between different types of vaccines.

?II. Animal factors

1. When vaccinating with a live vaccine, the animal's relatively high maternal antibodies or antibodies remaining from previous immunization cause immune interference with the vaccine.

2. The animal was already in a latent infection at the time of vaccination, or pathogens were introduced by the vaccinator or the instruments during vaccination.

3. The presence of immunosuppressive diseases in the animal herd, or the presence of other diseases, temporarily reduces immunity and leads to onset of disease.

?III. Human factors

1. Vaccination work is not done carefully. For example, there are insufficient drinking water containers during drinking water immunization, the vaccine is diluted incorrectly or unevenly, the vaccination dose is insufficient, or some animals are missed during vaccination.

2. The immunization route or method is wrong, for example, using the drinking water method to vaccinate with an inactivated vaccine that can only be injected.

3. Immunosuppressive drugs were used before or after vaccination, or antibacterial drugs were used during immunization with live bacteria.