Vaccines are pharmaceutical products that are intended to be administered to healthy animals to better prepare the animal's immune system to combat bacterial, viral, or protozoal health challenges. More simply stated, vaccines are intended to be used to prevent disease and generally do so through establishing and maintaining relatively high levels of circulating antibody titers. Because antibody titers wane over time, it is important that vaccines be administered and readministered (often referred to as "boostered") at the times necessary to result in antibody coverage throughout expected or potential exposure to disease-causing pathogens.
It is critically important to recognize that vaccines are intended to be preventive tools, and the efficacy of any tool can be impacted by how it is used. Because vaccines are biological products, they are often susceptible to environmental abuse and exposure to conditions outside of certain optimal ranges. As such, vaccines should be stored, handled, and administered in ways that are described on the label using techniques that protect product efficacy.
The product label contains the information necessary to ensure that product storage, handling, and administration practices do not limit or negate product efficacy. Deviations from such instructions may result in decreased product efficacy. In general, most vaccines should be refrigerated, but not frozen, and should remain within the desired refrigerated temperature range throughout storage, transportation, and up to the time of administration.
The most common causes of decreased efficacy are storage, transportation, and handling abuse. Examples include not transporting vaccines in coolers, not storing vaccines in coolers on working days, and storing vaccines in refrigerators that do not maintain temperature within the necessary range. Vaccines that will be stored for extended periods of time should be stored only in refrigerators that have been verified to maintain the correct temperature range. Data-logging thermometers are an inexpensive but valuable investment.
Vaccines, including vaccine vials and loaded syringes, should also be protected from direct exposure to sunlight. In addition, vaccines that have been exposed to the environment by puncturing the seal with a needle should not be stored and reused. If a needle has been inserted into the vial, the vaccine should be used during that working event, and any unused contents discarded per label directions. Storing previously opened vaccines allows for the potential growth of harmful microorganisms, and thus should be avoided in order to minimize the risk of unintentionally causing an adverse reaction or health event.
Some vaccines require reconstitution by adding diluent to a dehydrated powder. All vaccines require mixing or agitating before administration. Mix vaccines gently by slowly swirling and inverting unless the label specifies otherwise.
If reconstitution is required, reconstitute and mix only the amount of vaccine that will be used within an hour or less. Do not mix the entire day's allotment of vaccine at the beginning of a working event. It is good practice to reconstitute and mix only a single bottle of vaccine at a time.
Disposable syringes and needles should be discarded after each use. Repeatable, repeater, or "pistol-grip" style syringes should be cleaned after each use. Do not use soap, cleaning agents, or chemical disinfectants to clean reusable syringes. Rather, flush them repeatedly with hot water. Water should be boiled and allowed to cool slightly before repeatedly filling and emptying the syringe.
Transfer needles should be boiled in water, then allowed to dry before storage and eventual reuse. Syringe lubricants are not recommended because they represent a potential risk to product efficacy through interaction with the active components of the vaccine. Syringe lubricants are also unnecessary because the initial draw of a vaccine into the syringe provides adequate lubrication.
Syringe O-rings should be replaced as necessary, and extras should be kept on hand so that they are available when needed. This will help to minimize the risk of a syringe failure.
Similarly, vaccine efficacy may be limited by the ability of the animal's immune system to adequately respond to the vaccine. There are a number of animal-related factors that may influence vaccine efficacy. Of these, nutrition and environmental stressors are the most common.
Both nutrient deficiencies and toxicities can impair immune function and, as a result, influence an individual animal's response to a vaccine. Trace mineral, protein, and energy deficiencies are the most common nutrition-related issues that limit vaccine efficacy.
Energy deficiencies are generally easy to identify through low levels of animal performance, low body condition, and general unthriftiness. Trace mineral and protein deficiencies are often more difficult to visually identify. Trace mineral deficiencies, however, are easy to correct through supplementing with minerals or including trace mineral sources at adequate (but not excessive) levels in a complete ration.
Consumption of mycotoxins, other toxins, or other antinutritional factors may also impact vaccine efficacy. In addition, preexisting disease, heavy parasite loads, heat stress, and cold stress are all conditions that may also influence the animal's immune system and as a result, its ability to fully respond to a vaccine.
Although certain vaccinations are highlighted in this chapter, their mention should be considered a general rule of thumb. Their necessity for a given herd health program, or the lack thereof, may be subject to interpretation or opinion. The herd veterinarian is best positioned to provide direct recommendations on vaccination programs, including which components should be considered essential, and their optimum timing of administration.
Generally speaking, modified live virus (MLV) vaccines typically do not require revaccination to result in an effective antibody response. Killed virus (KV) vaccines, or combined KV and MLV vaccines, generally do require a revaccination (or booster) to result in an effective vaccination as defined by antibody response.
Vaccines that require revaccination should be readministered within the period of time described on the product label. Vaccines that do not require revaccination should be administered at or near the time of weaning. Nonetheless, the product label and herd veterinarian should determine if and when revaccination is necessary to result in an effective antibody response.
A strong, comprehensive beef cattle vaccination program begins with implementation at the cow-calf level. From a life cycle standpoint, preweaning calfhood vaccinations are the greatest opportunity to initiate a comprehensive and effective vaccination program.
Timing of preweaning vaccinations generally coincides with other working events, such as branding, prebreeding vaccinations of the cow herd, or bull turnout. Vaccinating calves at this time will help to minimize the risk of preweaning disease and will better prepare them to withstand the stress of weaning.
Calfhood vaccination programs should at minimum include vaccination against various clostridial and viral respiratory diseases. Common essential components of calfhood viral respiratory disease vaccines include:
In addition, clostridial disease vaccinations commonly include coverage against the following:
and may also include C sordelli and/or C tetani .
Some calfhood vaccination programs may also include vaccination against bacteria such as Mannheimia haemolytica and Pasteurella multocida , which cause bovine respiratory disease (BRD). It is important to recognize that this is not a comprehensive list, and specific vaccine decisions should be made in consultation with the herd veterinarian.
The vaccination programs of calves that will be developed to become replacement heifers also commonly include vaccination against reproductive diseases and should be similar to the vaccine program used for the mature cow herd. In addition to IBR and BVD, and depending upon local disease risk, vaccination against Brucella , Leptospira , Vibrio , Trichomonas , Campylobacter , or anthrax may also be warranted or recommended. Brucellosis vaccination must be performed according to state regulations.
Modified live vaccines for IBR and BVD give the broadest immunity to strain differences and should be administered twice to ensure a high level of immunity. Some evidence suggests that MLV BVD and IBR vaccines may affect the ovary for a short period of time after vaccination and potentially result in a minor decrease in fertility when administered immediately before or during the breeding season. For this reason, MLV IBR and/or BVD vaccines should be administered at least 1 month before the beginning of the breeding season.
While vaccination of heifers with Trichomonas vaccine may increase calving rate and decrease the duration of infection in infected herds, it is important to recognize that it may not prevent infection. Vaccination against trichomoniasis may be useful in infected herds or in herds at high risk of infection, but may not yield a positive return on investment in low-risk herds. These decisions should be made in consultation with the herd veterinarian and should be based upon risk of exposure and potential economic impact.
Prebreeding vaccinations should be completed at least 4 weeks before the onset of the breeding season. Precalving vaccinations are intended to protect the newborn calf through colostral transfer. It may be possible for precalving vaccinations to serve as effective prebreeding vaccinations; however, it is important to ensure that the vaccination program will provide sufficient duration of immunity to cover cattle throughout the time of greatest risk.
In addition, vaccination against bacterial scours (calf diarrhea) can be a beneficial component of a herd health program. Bulls should receive the same vaccines as the cow herd, with some exceptions. Bulls should not be vaccinated for brucellosis. Similar precautions with MLV IBR vaccines should be taken for bulls as for cows.