Dear Dr. Hassan

There are many causes of vaccine failure including

1- Vaccination Program :Each region typically has its own specific diseases .

2- Administration and Handling of the Vaccine:

A well designed vaccination program will not be effective if the vaccine is damaged by improper handling prior to administration. Live vaccines can be inactivated when exposed to adverse conditions.

3- Improper vaccine administration of the vaccine is the most common cause of vaccine failure in poultry.

4- The immune status of the breeder flock can have an affect on the success of progeny vaccination

5- Stress may reduce the chicken's ability to mount an immune response

6- Chickens may also already be incubating the disease at the time of vaccination. Despite proper administration .

7- Vaccine Quality

8- Many diseases are caused by agents that consist of several different strains/serotypes. For example, there are more than 100 recognized strains of IBV .

and another causes.

best wishes and kindly regards

Hi Dr.

In addition to general factors that cause failure in vaccination programme, it may be due to local strain variation.

Regards.

Dear Hassan

There are many points contributed in the failure case, please read in the following link :

https://edis.ifas.ufl.edu/pdffiles/VM/VM13600.pdf

Good Luck

Dear Hassan,

There are majority of reasons against IB vaccine failure, but the essentials/common are the below:

1. Variation in the strain of virus, as we repeatedly administered the same strain of vaccine but haven't researched the variation in the strain of virus, that why resistant created.

2. Improper administration of vaccine

3. Vaccine quality

4. Proper time / schedule due on region, not same everywhere

Maybe more reasons when fully investigate the problem...

Thank you,

Hamdard

Dear Dr. F.AL-Araji

I'm grateful for there answers

Dear

A.R.A. AL-Aqaby

Khalid Hassan

Enayatullah Hamdard

I'm grateful for this answers

thank you

thanks a lot

iagree with dr Furqan

very good question while answers are fair enough

good luck

Dear

Dr. Aamer

Dr. Heba

Dr. Alaa

so Dr. Monyer

I'm grateful for their answers

regards

Vaccines are used to prevent or reduce problems that can occur when a poultry flock is exposed to field disease organisms. Vaccinations should be thought of as insurance. Like insurance, there is a price to be paid for protection against a potential threat. Costs include price of the vaccine, time spent designing the vaccination schedule and administering the vaccines, and losses due to vaccine reactions from the live-type vaccines and localized tissue damage from killed-type vaccine injections.

thanks a lot Dr. Wisam for this answer

regards

Hi

all thanks

Dear

In general failure of vaccination refer to error of defect in one o f three factors or in all ( host , vaccine , worker ) in many details

dear Dr.Hassan

In general successful vaccination depend upon choosing perfect time ,route and strain as well as experience of team that apply the vaccine

there are some factors affect on vaccine failure, the first one is storage condition of vaccine before use and the reality uses method of vaccine

Hi Dr. Hemin Nuradden

I'm grateful for your answer

regards

Dear Dr.

Qassim Kshash

Jinan Abdulrahman

I'm grateful for their answers.

thanks a lot

Almost all the relevant points are covered, except one. It is immuno suppression due infection of any other immunosuppressive organisms( like Infectious Bursal Disease) or due to other non infective reasons( like Inbreeding Depression).

Thanks

I agreed with Dr. furqan answer

Hi

Very good and important and practical question.

I think that the answer of Dr Al-Arai is fairly enough.

Many thanks and regards

Good question I will follow it

I agree with the answer by Dr. Shibabrata Pattanayak

Regards

Dear Dr.Shibabrata Pattanayak

I'm grateful for your answer

regards

Thank you Dr.M.G.E. Gadallah

thank you Dr.

Atiaf Ghanim

Abbas Daham

Orooba Mtab Faja

regards

Iagree with Dr.Furqan

I agreed with Dr. furqan answer

iagree with dr Furqan

Dear Dr. Zahira

I'm grateful for your answer

Dear Dr. Mansoor

thanks a lot

regards

I'm grateful Dr. Hala

thx

Hi Dr I agree with Dr Aamer

Thank you Dr. Khalil

best regards

Hassan

iagree with dr Furqan

thank you Dr. Massar

best regards

Dear Dr. Hassan

There are many causes of vaccine failure including

1- Vaccination Program :Each region typically has its own specific diseases .

2- Administration and Handling of the Vaccine:

A well designed vaccination program will not be effective if the vaccine is damaged by improper handling prior to administration. Live vaccines can be inactivated when exposed to adverse conditions.

3- Improper vaccine administration of the vaccine is the most common cause of vaccine failure in poultry.

4- The immune status of the breeder flock can have an affect on the success of progeny vaccination

5- Stress may reduce the chicken's ability to mount an immune response

6- Chickens may also already be incubating the disease at the time of vaccination. Despite proper administration .

7- Vaccine Quality

8- Many diseases are caused by agents that consist of several different strains/serotypes. For example, there are more than 100 recognized strains of IBV .

and another causes.

best wishes and kindly regards

thanks a lot Dr. Furqan for this information

regards

Hi

may be due to using of no specific local strain.

thanks a lot Dr. Noaman for this information

regards

شكري وثنائي لكم دكتور على جهودكم العلمية بالتوفيق