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This page contains information on Twinvax-MR for veterinary use.
The information provided typically includes the following:
  • Twinvax-MR Indications
  • Warnings and cautions for Twinvax-MR
  • Direction and dosage information for Twinvax-MR


This treatment applies to the following species:
Manufacturer: Intervet/Merck Animal Health

Newcastle-Bronchitis Vaccine, B1 Type, B1 Strain-Mass. & Conn. Types Live Virus

U.s. Vet. Lic. No.


Active Ingredient(s)

TWINVAX®-MR is a combination live virus vaccine prepared from selected mild reaction infectious bronchitis virus strains (B1 strain, Connaught Massachusetts and Connecticut types) and the B1 strain Newcastle virus. The vaccine contains gentamicin as a preservative.

Twinvax-MR Indications

For vaccinating healthy chickens as an aid in preventing infectious bronchitis and Newcastle disease.

Twinvax-MR Dosage And Administration

When to Vaccinate: Initial Vaccination:

Beak-O-Vac Method: One (1) day of age.

Water Method: Two (2) weeks to 16 weeks of age.

Revaccination: Birds vaccinated initially before four (4) weeks of age should be revaccinated by water or spray methods at four (4) weeks of age or older with the appropriate vaccine.

Vaccination Program: The development of a durable, strong protection to disease depends upon the use of an effective vaccination program as well as many circumstances such as administration techniques, environment and flock health at the time of vaccination. Also, the immune response to one (1) vaccination under field conditions is seldom complete for all animals within a given flock. Even when vaccination is successful, the protection stimulated in individual animals against different diseases may not be life-long. Therefore, a program of periodic revaccination may be necessary.

Preparation of the Vaccine:

For Beak-O-Vac Use:

1. Do not open and mix the vaccine until ready for use.

2. Mix only one (1) vial at a time and use the entire contents within two (2) hours.

3. Remove the tear-off aluminum seal and stopper from the vial containing the dried vaccine.

4. Remove the tear-off aluminum seal and stopper from the bottle containing the diluent. Insert the long end of the adapter into the diluent bottle.

5. Hold the diluent bottle firmly in an upright position and insert the vaccine vial on the adapter of the diluent bottle. The neck of the vaccine vial should snap into position and should be seated securely on the adapter on the diluent bottle.

6. Invert the two (2) containers so that the vaccine vial is on the bottom and allow the diluent to flow into the vaccine vial. If the diluent does not flow freely, squeeze the bottle gently and the diluent will flow into the vaccine vial. The vaccine vial should be completely filled with diluent to prevent excess foaming.

7. Hold the joined containers by the ends and shake vigorously until the vaccine plug is completely dissolved.

8. Return the joined containers to their original position (diluent bottle on the bottom). Allow the rehydrated vaccine to flow into the diluent bottle. If the vaccine does not flow into the diluent bottle, tap or squeeze the diluent bottle gently and release to draw the vaccine into the diluent bottle. Be sure that all of the product is removed from the vaccine vial.

9. Remove the vaccine vial and adapter from the neck of the diluent bottle.

10. The vaccine is now ready for beak-o-vac use.

For Water Use:

1. Assemble the vaccine and equipment needed to vaccinate the entire flock at one time.

2. Do not open and mix the vaccine until ready for use.

3. Remove the tear-off aluminum seal from the vaccine vial without disturbing the rubber stopper.

4. Use cool, clean, nonchlorinated tap water to which powdered milk has been added as directed under How to Vaccinate.

5. Holding the vial submerged in a pail of water or under a running stream of water, lift the lip of the rubber stopper so that the water (milk added) is sucked into the vial.

6. Reseat the stopper and shake to thoroughly dissolve the vaccine.

How to Vaccinate:

1. Drinking Water Method: Do not mix the vaccine into the drinking water until ready for use. Drinking water for vaccination should be mixed with powdered milk to prevent inactivation from chlorine or other water additives and also to stabilize the vaccine virus. The powdered milk should be added to the water at the rate of one (1) heaped teaspoon per three (3) U.S. gallons or 2.5 imperial gallons (3 g per 11 L); or one (1) heaped cupful per 80 U.S. gallons or 66 imperial gallons (90 g per 300 L).

Withhold water from the birds for several hours before vaccinating so that the birds are thirsty. Thoroughly clean and rinse all watering containers so that no residual disinfectants remain. Dilute the vaccine immediately before use with cool, clean, nonchlorinated water (milk added). Pour the dissolved vaccine material into the following amounts of water and mix thoroughly.

Each 100 Birds

U.S. Gallons

Imperial Gallons

Metric Liters

2 to 4 weeks




4 to 8 weeks




Over 8 weeks




Distribute the diluted vaccine so that all of the birds are able to drink within a 1-hour period and do not add any more water until the vaccine is consumed. Avoid placing water in direct sunlight.

2. Spray Method: For revaccination only. Proper spray application of the vaccine is accomplished through the use of a clean sprayer only. The droplet size of the spray is important: a fine mist (spray droplets of 5-20 microns) will produce a stronger immune response, but may also elicit strong reactions. A coarse spray (spray droplets of 30-50 microns) will produce less respiratory reactions, but will also reduce immunity. Environmental conditions, bird strain and bird health will determine which droplet size is appropriate for an operation. Only use the spray method in houses that can be closed during vaccination and for 15 minutes thereafter. Cross winds, drafts or operating ventilation fans will prevent effective application.

Rehydrate the vaccine according to the above instructions “Preparation of the Vaccine for Beak-O-Vac Use”.

Further dilute each 2,500 doses (75 mL) of vaccine to 250 mL, each 5,000 doses (150 mL) of vaccine to 500 mL, or each 10,000 doses (300 mL) of vaccine to 1,000 mL using distilled water. Place the rehydrated vaccine in the sprayer container. Apply the vaccine at the rate of one (1) dose per square foot or one (1) dose per bird, whichever is greater. The vaccine should be applied at the rate of 700 doses of vaccine per minute. See the manufacturer’s directions for the spray applicator to choose for more specific application directions.

Use protective goggles during vaccination to avoid eye contact with Newcastle vaccine.

3. Beak-O-Vac Method: Only use this method for the vaccination of day-old chicks in the hatchery. Proper beak-o-vac application of the vaccine is only accomplished through the use of a clean disinfectant-free beak-o-vac machine (or equivalent automatic debeaking vaccinating machine) adjusted to deliver 33 to 34 doses per mL of the final rehydrated vaccine.

Using an appropriate clean sterile disinfectant-free tubing, hook up the final mixed vaccine to the beak-o-vac machine. Make sure that all of the air bubbles are removed from the delivery tubing and that the proper dosage is delivered consistently with each debeaking action of the machine.

Hold the chicks so that the mouth of the bird is open and across the spray bar at the vaccine delivery point to ensure that the vaccine is sprayed directly into the entire oral cavity of the bird; thus, exposing the upper respiratory tissues to the vaccine virus.

Beak-o-vac machine operators should use protective goggles during vaccination to avoid eye contact with Newcastle vaccine.

Records: Keep a record of the vaccine type, quantity, serial number, expiration date, and place of purchase; the date and time of vaccination; the number, age, breed, and location of the birds; the names of operators performing the vaccination; and any observed reactions.


As will all bronchitis vaccines, the initial vaccination of layer or breeder replacement stock should be conducted before 16 weeks of age to avoid possible damage to reproductive organs. For the same reason, at least one revaccination with a bronchitis vaccine should be conducted before 16 weeks of age.


Store at 35° to 45° F (2° to 7°C).

Twinvax-MR Caution(s)

For veterinary use only.

1. Vaccinate healthy birds only. Although disease may not be evident, coccidiosis, chronic respiratory disease, mycoplasma infection, lymphoid leukosis, infectious bursal disease, Marek’s disease, or other disease conditions may cause serious complications or reduce protection.

2. All birds within a house should be vaccinated on the same day. Isolate other susceptible birds on the premises from the birds being vaccinated.

3. In outbreak situations, vaccinate healthy birds first, progressing toward outbreak areas in order to vaccinate diseased birds last.

4. Do not spill or spatter the vaccine. Use the entire contents of the vial when first opened. Burn the empty bottles, caps, and all unused vaccine and accessories.

5. Wash hands thoroughly after using the vaccine.

6. Do not dilute the vaccine or otherwise stretch the dosage.

7. Newcastle virus occasionally causes inflammation of the eyelids in humans, lasting two or three days. Avoid contact of the eyes with the vaccine.


Do not vaccinate within 21 days before slaughter.


Supplied in 10 x 2,500, 10 x 10,000, and 10 x 20,000 dose units. Diluent can be purchased separately.

Nac No.

556 MORRIS AVE., SUMMIT, NJ, 07901
Telephone:   862-245-4321
Order Desk:   800-648-2118
Fax:   862-245-4935
Customer Service:   800-521-5767
Every effort has been made to ensure the accuracy of the Twinvax-MR information published above. However, it remains the responsibility of the readers to familiarize themselves with the product information contained on the US product label or package insert.

Copyright © 2018 North American Compendiums. Updated: 2018-03-29