Short period of immunity following vaccination

Short period of immunity during vaccination can be caused by series of activities that goes around before, on or after the vaccination. The following could be the reasons;

1 Flock pre-vaccination handling: As it is the rule of thumb that sick birds should not be vaccinated because of the level of immunity, they have as then is low, which if vaccinated may pose stress on the birds and the body interaction might not favour the building of a good litter for the said used vaccine. For these reasons, there will be shorter period of immunity.

2 On vaccination procedures; majority of livestock handlers overlook prompt routines that has to be done prior and during a vaccination exercise which give rise to ineffective vacation exercise among which are using traces of disinfectant either to flush or clean the water system these will reduce the potency of the constituted vaccine, poor drinker to birds ratio, which posses some birds not having access to constituted vaccine, longer period of water withdrawal from the flock which will be a stressor as all source of stress should be minimized during vaccination, vaccine choice (is it the right strain to be used in your area, how about the cold chain) vaccine reconstitution process is it done in the right way, Quality of the water used (is free from ions and minerals which can bind and reduce the potency? And is the water also free of chlorine?) It's  also important to look into the temperature of the house during vaccination.

3 Post-vaccination handling of the flock; vaccination can be correctly done with right vaccine and it poses good titer but the activities on the flock, which induces stress on the flock (i.e outbreak of diseases, heat stress, activities on the farm, medication), can affect the length of immunity on the flock.

Route of vaccination to be administered is also an important factor for immune response and duration of vaccination titers as drinking water route is on low rating immune response as compared to aerial spray method of vaccination.

The I feel the left out is the timing. In some case, vaccination are done in a short interval before the immunity subsides another antigen is put in. This neutralizes the antibody developed and will leave the birds unprotected. Here in Uganda, it is common where farmers vaccinate against Gumburo in the first week of the life of the chicks. In that period there is still maternal immunity and if you do vaccinate you will neutralize the maternal antibodies leaving the birds unprotected. It is one of the reasons why most farmers get attacked by Gumboro infection in the 3 or 4th week despite the fact that they did vaccinate.

The strain of vaccine may be milder than host immune so difficult overriding. If you want to get long immunity, you have to use killed vaccine at the onset of lay and mid lay, and vaccination technic for good uniform immunity for preventing rolling reaction.