If a person is vaccinated but does not have a protective effect, and still gets the infectious disease that has been prevented, it is called immune failure. There are many reasons, not necessarily the vaccine, but an inappropriate immune response. For example, malnutrition such as vitamin A or E deficiency can also inhibit the body's normal protein synthesis, thereby reducing the immune response. In addition, if the injection interval is too short, interference between vaccines will occur. If the injection interval is too long, the effect will be reduced. Here are a dozen common causes of immune failure.

1. The problem of maternal antibodies

Newborn puppies or kittens are protected by receiving antibodies from their mother through the placenta or colostrum. When should you start vaccination? This is related to the level of maternal antibodies.

The time that maternal antibodies circulate in the body is different in different individuals and different antibodies.

Each individual has a susceptible period, which varies in length from days to weeks, during which the level of maternal antibodies is high enough to prevent vaccines from working, but low enough to not protect against infectious diseases. Even if you are vaccinated during this period, you can still get infectious diseases. The susceptibility periods are also different between different litters and even between different individuals in the same litter.

Research shows that against parvovirus, puppies are only 25% effective at 6 weeks of age, 40% effective at 9 weeks old, 60% effective at 16 weeks old, and 95% effective at 18 weeks old.

2. The interval between vaccination and exposure to infectious diseases is too short

Vaccines do not immediately stimulate the body to produce antibodies as soon as they are vaccinated. It takes several days to weeks to produce effective antibodies. For example, coronavirus can only produce effective protection 2-3 weeks after the second vaccine injection.

When a pet is vaccinated, it is already in the incubation period of the disease, or there is a severe parasitic infection. After vaccination, the pet will inevitably become ill, resulting in a failure of immunity.

3. Different strains of viruses or bacteria

If the virus or bacterial strain mutates, the vaccination will also fail. For example, recently, a mutant strain of parvovirus was discovered clinically, and as a result, conventional parvovirus vaccination failed.

4. Vaccine damage

Due to improper storage or transportation, attenuated vaccines may become inactivated and cause immune failure; if the temperature is higher than 4℃ during the storage and transportation of the vaccine, the vaccine will also become ineffective.

5. Improper use of vaccines

The route of vaccination is not carried out according to the requirements of the vaccine, such as subcutaneous injection, intramuscular injection or intranasal drip. Also, be sure to follow the dosage (support)injection. Dog vaccines are based on head dose, not weight, age, etc.

6. Improper immunization procedures

If the injection interval is too short, interference will occur between vaccines. If the interval is too long, the effect will be reduced. Usually, the injection interval of the two vaccines is 2-3 weeks, which is more reasonable, except of course for rabies.

7. Different varieties

Different breeds have different sensitivity and responses to infectious diseases. For more sensitive breeds, the immune program may need to be adjusted.

8. Immunodeficiency

If the body's immune system is defective and cannot produce a normal immune response to the vaccine, it will also fail.

9. During the illness

Fever can suppress the body's immune response to canine distemper virus DD, and infection with certain viruses can also reduce the body's immune response to vaccines. Therefore, we have always emphasized that dogs need to be vaccinated when they are healthy.

10. Malnutrition

Malnutrition such as vitamin A or E deficiency can also inhibit the body's normal protein synthesis, thereby reducing the immune response.

11. Immunity failure caused by the vaccine itself

(1) Vaccines have a certain validity period, and expired vaccines cannot be used.

(2) Poor quality of the vaccine or poor quality of the vaccine diluent (distilled water and physiological saline) will also affect the immune effect.

(3) The vaccine’s autoantigen content is insufficient.

(4) The vaccine is contaminated with other pathogenic microorganisms (especially live vaccines), which will interfere with or inhibit antibody production.

(5) Inactivated vaccines produced with virulent strains are not completely inactivated.

(6) Improper configuration (selection) of immune adjuvants.

(7) Problems in vaccine transportation and storage, especially interruptions in the cold chain.

12. Equipment used for immunization

Unsterile syringes, needles and droppers will reduce the performance of the vaccine; unsterilized or contaminated diluent will cause the vaccine to be impure; using chlorine-containing tap water to dilute the vaccine will reduce the immune activity of the vaccine and cause immune failure.

13. The vaccine is used for too long after dilution

Freeze-dried seedlings taken out from the refrigerator at dozens of degrees below zero should beLeave it for a period of time to minimize the temperature difference with the diluent to avoid premature death of weakened microorganisms in the vaccine due to a sudden rise in temperature.

In addition, if the ‘warming’ step is not done well and the temperature of the vaccine injected into the animal is too low, it will also cause the animal to have a strong stress response and affect the effectiveness of the vaccine immunity.

Friendly reminder: To sum up, this is why even if so many pets are vaccinated now, there are still reasons for vaccination failure, especially in China, which is still the hardest hit area for pet infectious diseases. In a word, it does not mean that vaccination can achieve 100% protection for the vaccinated animals.

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