Vaccines and Boosters for Cats (FVRCP and Rabies)!!!

[Chris]

Hi Adam, I’ll answer the FVRCP/HCP portion of the question first. When it comes to this vaccine, it’s not about there being a 1 year or 3 year version of it and there is no different labeling, it gets into vaccine schedules and medically accepted rationale. The American Association of Feline Practitioners releases guidelines on vaccine schedules for cats, more of which you can find info on here:

In general, when we vaccinate kittens (and puppies), we start at around 8 weeks. Maternal immunity from the mom disappears somewhere during this time up to around 12 weeks. This is why we vaccinate every 3-4 weeks during this age range until 4 months. It’s known that an initial vaccine provides poor immunity and needs boostering at a certain interval for a proper antibody response. That last vaccination at 4 months is expected to last for one year. The same goes for an adult cat getting vaccinated for the first time. A booster is needed in 3-4 weeks. Since we’re not working against maternal immunity like with a kitten, only one booster is needed. After that annual booster, further FVRCP/HCP vaccines only need to be done every 3 years.

Is it possible the vaccine lasts longer? Sure, it may be possible. But that may vary considerably among individual cats. Checking vaccine titers is an option, but they’re comparatively expensive, prohibitively even. We have rare clients who prefer to spend $300-400 on a titer instead of a $60 vaccine. And before someone comments on this being a conspiracy for vets to line their pockets, titers are expensive for people too but very few people ever have vaccine titers done. Veterinarians and licensed technicians must be rabies vaccinated and so must have titers done every couple of years. It’s fun when you’re insurance company doesn’t understand why that’s necessary and makes you pay that out of pocket.

A 3 year vaccine can continue to be given as long as there are no breaks in the intervals. If there has been, then according to the vaccine labeling, the next vaccine should be a one year again. However, vets may handle these lapses differently. If the vaccine has lapsed by only a month, a 3 year may still be medically appropriate when weighing the risk with vaccine frequency. If it’s been lapsed by a year or more, and especially if there is some inherent risk (like a new cat to the home who may pass on herpes or calici) a one year vaccine or even restarting the initial/booster series may be more appropriate.

In other words, don’t assume if the vaccine was given as a one year that you can just count it as a three year. It depends a lot on what immunity we’re looking to achieve and when.

When it comes to rabies vaccine, it’s a bit more complicated, because this is the only vaccine that is legally required and can have more concerning ramifications if the vaccine label is not followed.

The rabies vaccine given to dogs can be considered a one or three year vaccine, not unlike the same rationale behind the FVRCP/HCP vaccine. This rabies vaccine is also labeled for use in cats as a 3 year. However, it’s an adjuvanted vaccine (an inactive component designed to extend immunity) which is thought to carry a higher risk of vaccine/injection site sarcomas in cats.

Merial then came out with the PureVax rabies vaccine, which has no adjuvant. I only mention this, because for some time, a one year meant getting the PureVax vaccine and a 3 year for cats meant getting the cat/dog adjuvanted vaccine, with long discussions about the risk vs. benefit of using that vaccine in cats.

Then Merial (now part of BI) came out with the 3 year PureVax vaccine. My own practice only started carrying it about a year ago. It’s 3 times as expensive (but also means it’s 3 times as much for veterinary practices to purchase it). It’s distributed in much smaller batches and carries a completely different label. While it utilizes the same recombinant vaccine technology, it doesn’t make sense to me that it’s the exact same formulation. I have seen many opinions that that’s the case, but for the batches to be smaller and the price at cost to clinics to be much higher, that implies it’s more expensive to produce. I’m going to compare product inserts and get in touch with a BI rep to try to understand more details.

But the last part to relay is that regardless of the formulation, it’s important that the proper labeling is followed, especially when it comes to rabies vaccination. If there is an incident (such as a cat biting a person, getting into an altercation with rabies suspect wildlife, even a bat or other rodent that gets into the house) and the rabies vaccination is not up to date per its label, the cat will be treated as unvaccinated. This relates to different quarantine periods for the cat in those cases. And when it comes to international travel (which I realize affects only a small number of people) there is no compromising when it comes to rabies vaccine label intervals. Rabies is endemic in the United States, which is not the case in many other foreign countries and they are very protective and strict about it.

Rabies titers are not a substitute for vaccination, as they will not be legally regarded in place of a vaccine interval. We typically only run them as required for international travel depending on the country’s requirements. But in situations where there’s an incident and rabies status is in question, no health department will accept a titer in lieu of an up to date vaccine as the titer only shows immunity at one small point in time and doesn’t prove the cat had immunity at the time of the incident.

State or local jurisdictions may also have their own laws about acceptable rabies vaccination intervals that are important to be aware of.

[Adam]

Dear Chris,

Thank you so much for your prompt and detailed response!

So just to make sure:

My little lion boy received a Felocell 3 FVRCP vaccine on December 01, 2023, at the age of 10 months old (just after I adopted him). (I do not know his vaccination history before I adopted him…)

He then received a second vaccine which was the Nobivac Feline-1 HCP FVRCP vaccine booster on December 07, 2024, at the age of 1 year and 10 months old (as an adult).

His last booster (Nobivac Feline-1 HCP) has a labelled Duration of Immunity (DOI) of supposedly just one year (“1-year”). However, both vets that I spoke with cited the new AAHA vaccination guidelines stating that regardless of the last booster vaccine given (“1-year” or “3-year”), as long as the last vaccine was given when the cat was an “adult” (over 1 years old), then the vaccination interval should be 3 years for a FVRCP vaccine, and therefore his next booster should be given in December of 2027.

Is this correct???

I do not want to over-vaccinate my cat, nor do I want to go against the official advice of my veterinarians. However, I also want to make absolutely sure that my cat is fully protected from these terrible diseases which can be fatal.

Even though he technically received a “1-year” FVRCP vaccine (Nobivac Feline-1 HCP) in December of 2024, can we confirm that the Duration of Immunity (DOI) is actually for three years, and that his next FVRCP booster vaccine is not needed until December of 2027?

If you could please help me confirm this then I would be able to rest easier for the next two years! haha. Thank you so so much for your help! Take care.

All the best,

– Adam