When the weather turns cold, many pig farms start giving catch-up vaccinations and booster shots in batches. They vaccinate every year, yet some farms still see disease outbreaks afterward. Often, the problem isn’t the vaccine itself, but “which vaccine to choose, how to administer it, and how to manage it.”
This article gets straight to the point and walks through the key steps in autumn and winter vaccination, from planning to post-vaccination monitoring.
Check each animal individually before vaccination and prepare the vaccine according to protocol—this is the first key to successful immunization.
I. What to vaccinate against in autumn and winter, and how to vaccinate
According to the National Guidelines on Compulsory Immunization Against Animal Diseases (2026—2030), issued by four departments including the Ministry of Agriculture and Rural Affairs, foot-and-mouth disease remains a disease subject to compulsory national immunization. Population immunization coverage is maintained above 90% year-round, immunization coverage among livestock and poultry requiring immunization reaches 100%, and the pass rate for immunization antibody levels is no lower than 70% year-round. For classical swine fever and highly pathogenic porcine reproductive and respiratory syndrome, local authorities implement immunization for key farms and groups based on the local epidemic situation.
Which type to use, which strain to use, and when to administer booster immunizations should not be copied from a neighboring farm or based on old experience. Follow the immunization plan issued that year by the local animal disease prevention and control agency, and have the farm’s licensed veterinarian develop a plan based on the health status of the pig herd. A program tailored to each farm is the starting point for “scientific immunization.”
Routine plans should also take the farm’s specific circumstances into account for diseases such as pseudorabies, porcine circovirus disease, porcine parvovirus disease, swine erysipelas, and swine streptococcosis. In autumn and winter, also watch for risk periods for diseases such as foot-and-mouth disease, porcine epidemic diarrhea, and transmissible gastroenteritis; plan ahead rather than waiting until an outbreak occurs to make up for it.
Two. Live vaccines and inactivated vaccines are not the same thing
This is the easiest point to overlook, yet it directly affects success or failure.
Live vaccines (attenuated vaccines) contain weakened live pathogens. They can mimic a mild infection and stimulate a broader immune response, but they are “sensitive to antibiotics, stress, and the incubation period.” Inactivated vaccines contain killed pathogens. They are safer and do not shed pathogens, and usually require two or more doses, followed by a booster after an interval, to provide sufficient protection.
This leads to several hard-and-fast rules:
· For bacterial live vaccines, do not use antimicrobials that are effective against the relevant bacteria for about 7 days before and after vaccination. Otherwise, the medication will suppress the live vaccine, making the vaccination pointless. Similarly, avoid administering viral live vaccines when the pig herd is ill, experiencing high fever, or under severe stress.
· If the herd is showing signs of disease or is in the incubation period, do not administer a live vaccine hastily, as this may trigger or worsen the illness. First separate and treat the sick pigs, then vaccinate them once they have recovered.
· Whether inactivated vaccines can be administered at the same time as each other, or alongside live vaccines, and how long to wait between them, depends on the vaccine instructions and the farm veterinarian’s arrangements. Different vaccines and different injection sites should be kept separate; do not mix them in one injection.
Three. No matter how expensive the vaccine is, improper storage renders it completely unusable.
Vaccines are extremely sensitive to temperature. If any link in the cold chain is broken, their potency is reduced.
Most inactivated vaccines require refrigeration at 2–8°C and must never be frozen. Frozen oil-emulsion vaccines may break and separate into layers and cannot be used again. Most live vaccines require freezing or storage at 2–8°C (follow the instructions on the vial label); diluents must also be stored as required. Transport vaccines in a cooler with ice packs, avoiding direct contact between the vaccines and the ice packs to prevent freeze damage. Once at the barn, take out only what is needed for immediate use and protect it from light. After dilution, use live vaccines as soon as possible within the time specified in the instructions, generally no more than 2 hours; discard any that exceed this time.
Before use, inspect each vial: name, batch number, expiration date, whether the vial is cracked, whether the contents are discolored, cloudy, or separated, and whether any sediment cannot be dispersed by shaking. Do not use expired, deteriorated, or damaged packaging. This step must not be skipped.
Four. If the pig is unhealthy, vaccination is wasted
An immune response requires resources. Do not vaccinate pigs that have a fever, reduced feed intake, diarrhea, coughing or labored breathing, or poor alertness, or pigs under severe stress after weaning, regrouping, or long-distance transport. First help them recover, then provide catch-up vaccination.
Reduce stress around vaccination: avoid changing feed and regrouping animals at the same time; electrolytes and vitamins, for example, may be added to drinking water as directed on the product label to help relieve stress (the specific product and dosage should be determined by a veterinarian). When temperatures change sharply or conditions are hot and stuffy or severely cold, try to schedule procedures for a time of day when the temperature is suitable.
Maintain hygiene before and after immunization: thoroughly clean, boil, or autoclave needles and syringes; use one needle per pig (or at least one per pen, changing it promptly) to prevent horizontal disease transmission via needles. Disinfect the injection site with 75% alcohol or povidone-iodine, and let it dry before inserting the needle to avoid carrying contaminants into the body.
For the first vaccination of piglets, ensure secure restraint, accurate injection-site placement, and the full dose.
Five. Injection site, dosage, and procedure: do not be careless at any step
Choose an injection site on either side of the neck, behind the ears, where the muscles are well developed. Avoid nerves, blood vessels, and the subcutaneous fat layer. Insert the needle vertically or at the angle specified in the instructions to ensure the injection reaches the muscle. Do not inject into the buttocks, where the thick layer of fat leads to poor absorption and can easily cause lumps.
Follow the dosage on the vial label and in the instructions exactly; do not give too much or too little. An insufficient dose may not produce enough antibodies. Increasing the dose without authorization is wasteful and may worsen allergic reactions and stress. Calibrate the markings on syringes and continuous syringes in advance to ensure a consistent dose for every pig.
For live vaccines that need to be administered by nasal drops or spray (such as some vaccines for pseudorabies in pigs), keep the pig’s nostrils pointed upward and hold it briefly. Release the pig only after the liquid has actually been inhaled into the nasal mucosa. If the pig shakes its head and sprays the liquid out, administer the drops again.
Six. Allergies are rare, but when they happen, they’re serious.
Do not leave immediately after vaccination; observe for about 30 minutes. Some pigs may experience allergic reactions: rapid breathing, white foam around the mouth, bluish or reddened skin, trembling, inability to get up, or, in severe cases, shock or even death.
Keep emergency medicines such as epinephrine injection on hand at the site (prescription medicines, to be prepared and used under the guidance of a licensed veterinarian). If an acute allergic reaction occurs, administer an injection immediately in accordance with standard procedures. Also keep records of the batch number, number of pigs, time, personnel involved, and any abnormalities for traceability.
Within a day or two after vaccination, a small number of pigs may temporarily eat less, seem slightly lethargic, or develop mild local swelling; these are generally normal reactions. However, if there is a group-wide high fever, a large number of pigs eat less, or deaths increase, immediately stop the procedure, contact a veterinarian and the vaccine supplier, and report and submit samples for testing as required to determine whether the cause is the vaccine, the procedure, or another disease that was already incubating in the herd.
Seven: The job is not over after vaccination; monitoring and management must follow.
Vaccines are not a cure-all, and vaccination is not a one-and-done solution. Data should show whether immunity is working well: collect blood samples regularly for antibody testing and assess the results against the qualifying rate for immune antibodies (for diseases requiring compulsory immunization, this rate must remain at or above 70% year-round). If the rate falls short or results vary widely, investigate the cause and make up any missed vaccinations. This step helps you determine whether the vaccine was not administered properly or whether there was already an underlying problem in the herd.
Adjust the vaccination schedule based on your farm’s test results and changes in disease activity in the surrounding area; do not add vaccines blindly or arbitrarily bring vaccinations forward or delay them. Keep complete immunization records and logs, including the date, the pigs vaccinated, the vaccine used, batch number, dose, and person who administered it—leave nothing out.
Finally, remember that immunization is only one part of a biosecurity system. Dry, clean pens, thorough disinfection, rodent and insect control, all-in/all-out management, isolation and observation of purchased animals, and personnel and vehicle controls are all essential. Vaccines alone cannot contain every risk if these measures are not properly implemented. In autumn and winter in particular, balance heating and ventilation. Do not seal up the pig house to keep it warm, turning it into a damp, stuffy breeding ground for pathogens.
Effective immunity plus consistent management results in a healthy, uniform pig herd.
Make sure every injection is given to a healthy pig, at the correct site and in the full dose. Maintain the cold chain, monitor reactions, and conduct regular checks. When these practices are carried out properly, the vaccine delivers real value.