FYI: USDA Adverse Events Due to Vaccinations Reporting

The United States Department of Agriculture (USDA) has been implementing important and positive changes regarding adverse events that companion pets or livestock (feed animals) may have experienced due to a vaccination. We explain the changes and what you can do if your companion pet suffers from an adverse event.

What sparked these changes?

The Virus-Serum-Toxin Act was amended. It now requires veterinary vaccine manufacturers to record and submit records to the USDA’s Center for Veterinary Biologics (CVB) concerning adverse events associated with the use of the vaccines (i.e. biological products) they produce or distribute.

When do the changes take effect?

The CVB started phasing in the program in June 2018. The CVB plans on having it fully rolled out 18 months after that.

What is an adverse event from a vaccination?

The definition for what constitutes an adverse event is broad. This is good. According to the USDA website:

An adverse event is any observation in animals, whether or not the cause of the event is known, that is unfavorable and unintended, and that occurs after any use (as indicated on the label or any off-label use) of a biological product, including events related to a suspected lack of expected efficacy. For products intended to diagnose disease, adverse events refer to a failure in product performance that hinders an expected discovery of the correct diagnosis.

The USDA continue by providing examples:

Some animals, like people, may be uncomfortable or lethargic on the day they are vaccinated. More serious adverse events are less common possibility. Immune (hypersensitivity) reactions are infrequent but possible after exposure to any immune stimulating biologic (‘immunobiologic’) , as well as many other substances. Acute anaphylaxis with immediate collapse is a dramatic reaction that may happen shortly after vaccination. It is important to observe an animal for at least an hour after vaccination, so that it may be treated if necessary. Other reactions that have been observed within a day of vaccination include loss of appetite, fever, facial swelling, hives, nasal or ocular discharge, respiratory distress, vomiting, or diarrhea. Events occurring a day to two weeks after vaccination include similar events, as well as stiffness, local inflammation, and systemic illness, which may or may not be based on an immune reaction. If you have any concerns about the health of an animal after the use of an immunobiologic, consult your veterinarian promptly.

Your veterinarian is also an important source of guidance about the proper administration of these products. Not all properly vaccinated animals will be protected from the diseases of concern. Many factors affect the response of a particular animal to vaccination and the chance that it will subsequently succumb to that disease. Such factors include the animal’s genetic susceptibility, immune competency, its health at the time of vaccination, stress, environment, and the virulence of the pathogen. Even under optimal conditions, antigens vary widely in the strength and duration of the disease protection they confer.

The USDA gives additional variables that may affect vaccines:

The frequency of adverse events occurring in animals may vary depending on various factors such as age, species, breed, weight, environmental conditions, and any pre-existing health conditions of the patient(s). The use of other immunobiological products, pharmaceutical products such as antibiotics, or parasiticides such as flea and tick control products at the same time may also affect the frequency rate. Although a baseline frequency rate may be established, variable conditions may modify the frequency rate. It is important to note that not all adverse events are reported and, not all adverse events reported are actually adverse reactions (cause and effect relationship resulting from the use of an immunobiological product).

Overall, we commend the USDA for explaining adverse events and recognizing the additional factors that may play a part in causing adverse events, all of which we have been discussing for years (See examples below).

Other vaccination statements & policies

From the American Animal Hospital Association (AAHA) 2003 – Current knowledge supports the statement that — “ No vaccine is always safe, no vaccine is always protective and no vaccine is always indicated. Misunderstanding, misinformation and the conservative nature of our profession have largely slowed adoption of protocols advocating decreased frequency of vaccination”

From the World Small Animal Veterinary Association (WSAVA) 2015-2017 – By Prof. Michael J. Day

“Vaccination should be just one part of a holistic preventive healthcare program for pets that is most simply delivered within the framework of an annual health check consultation. Vaccination is an act of veterinary science that should be considered as individualized medicine, tailored for the needs of the individual pet, and delivered as one part of a preventive medicine program in an annual health check visit.”

What about other medications like antibiotics?

The Food and Drug Administration (FDA) Center for Veterinary Medicine (CVM) regulates veterinary drugs.

What can I do as a companion pet parent?

The beauty of the system is that the USDA has empowered companion pet parents by giving them the tools to report adverse events. This additional layer of reporting provides oversight and helps ensure manufacturer accountability if they fail to report accurately.

How do I report?

First, you or your attending veterinarian need to alert the manufacturer.

Then, you or your veterinarian need to report to the USDA’s CVB.

The CVB prefers online submissions via the USDA Adverse Event Reporting portal.

What does Hemopet suggest?

The reporting portal is lengthy and can be overwhelming.

Since this concerns the welfare and health of your companion pet as well as companion pets around the nation, we encourage accurate, thorough and complete reporting.

The CVB also offers a printable form that can be completed, and then mailed or faxed.

We suggest that you request your pet’s medical records from your veterinarian. Then, please print the USDA form, fill it out to the best of your knowledge, double-check it, edit, and have your veterinarian fill in the gaps.

From that point, you can input the information straight into the online portal or mail/fax it in. If you had to erase or scribble something in, we would suggest creating a fresh copy if you choose to mail/fax so CVB can read the handwriting.

Anything else of particular importance?

Yes! The USDA only wants active cases. The reporting system is designed to monitor vaccine products that have not expired. Therefore, reporting is TIME SENSITIVE. So, please do not submit what you may have considered an adverse event years ago. Remember, we need to be taken seriously for the system to work.

What happens after I report?

When necessary, the CVB may order testing or seek out information. The CVB is, however, unable to make diagnoses or recommendations specific to individual cases. Some of the manufacturers do provide such services. Receipt of a report by the CVB does not necessarily imply that the product caused an adverse event, or even that a particular event actually occurred. Please remember, the USDA is a regulatory agency, not a research agency.


Common Questions about Pharmacovigilance. United States Department of Agriculture Animal and Plant Health Inspection Service, 3 July 2018,

Dodds, W J. Vaccine issues and the World Small Animal Veterinary Association WSAVA guidelines (2015-2017). Israel J Vet Med 2018:73(2):3-10.

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