What happens if my kitten has had an adverse reaction before?

If your kitten has had a reaction to a vaccination in the past, then you may understandably be reluctant to revaccinate them. However, there is a protocol in place for how these cases will be handled. Kittens that experience adverse reactions to core vaccines, will still need these repeated. Your vet may recommend serological testing to determine your cat's level of immunity and only vaccinate them when immunity drops. They will also likely administer an antihistamine before the next dose to prevent the reaction occurring and then your cat should be monitored closely for the next 24 hours. Optional non-core vaccinations are not recommended to repeat following an adverse reaction.

What is an Injection Site Sarcoma?

What Is An Injection Site Sarcoma? You may have heard the term Feline Injection Site Sarcoma (FISS) and be wondering if your kitten is at risk. A FISS is a type of malignant cancer that cats are prone to developing at the site where an injection has been administered in the past. These can follow any type of injection, not just vaccinations; including microchips, fluids and medications. Injection Site Sarcomas only occur in 1 out of 10,000 cats, so are extremely rare.

Do indoor cats need to be vaccinated?

The simple answer is yes. Core vaccinations are required by all cats, regardless of lifestyle. The diseases that these vaccinations protect against are highly contagious and can be transmitted by an infected cat in all excretions. Air-borne particles can travel several metres and the virus can survive in the environment for weeks. Even if your kitten stays inside the house, you could potentially touch a contaminated cat or environment and spread the virus to your kitten at home. Some of the viruses, notably Feline Herpesvirus-1, can also remain latent in carrier cats. These cats can shed the virus into the environment without showing any symptoms. Carries of Feline Calicivirus typically last a couple months, but can be lifelong. Feline Herpesvirus-1 is lifelong in all infected cats and can be contracted from an infected mother at birth. Cats with latent infections will often experience disease during times of stress.

Can my kitten still become infected even if they are vaccinated?

Vaccinations aim to prevent disease and reduce the severity of illness, they do not stop your kitten or cat from becoming infected. Reasons why a vaccination may not be successful are due to there being various different strains of the virus, persistent maternal antibodies that may respond to the vaccine, if your kitten was unwell at the time of vaccination or if your cat was infected with 'Cat Flu' prior to administration of the vaccine. Both Feline Calicivirus and Feline Herpesvirus-1 are part of the Cat Flu Complex and common causes of cat flu symptoms. Many cats will experience Cat Flu during times of stress, usually presenting respiratory symptoms like sneezing, eye and nasal discharge, coughing and lethargy. If your cat has ever had Cat Flu, then they may have been infected with one of these viruses at some point. Check out our Cat Flu Article to read more about the Cat Flu complex, symptoms and management.

What is the difference between an F3 and an F5 vaccination?

An F3 vaccination is the "core" vaccine required for all cats; it protects against Feline Panleukopaenia, Calicivirus, and Herpesvirus. An F4 or F5 includes these core components plus "non-core" protection against Feline Leukaemia Virus (FeLV) and/or Feline Immunodeficiency Virus (FIV), which is often recommended for cats with outdoor access.

Why does my kitten need three shots instead of just one?

Kittens start life with "maternal antibodies" from their mother's milk. These antibodies are great for protection but actually block vaccines from working. Since we don't know exactly when these maternal antibodies wear off (usually between 6 and 16 weeks), we give a series of boosters to ensure there is no "gap" in their immunity.

How soon after the final kitten vaccination can my cat go outside?

It typically takes about 7 to 14 days for the immune system to fully respond to the final vaccine. To be safe, it is best to wait at least two weeks after the 16-week booster before allowing your kitten to explore the great outdoors or interact with other cats.

Is it normal for my kitten to be sleepy after their vet visit?

Yes, a little bit of "quiet time" is quite common. Because the vaccine is busy waking up their immune system, some kittens may feel slightly lethargic or have a decreased appetite for 24 to 48 hours. If they seem very distressed, start vomiting, or develop facial swelling, you should contact your vet immediately.

Last Updated: 29/12/2025

Kitten Vaccination Schedule: the Ultimate Guide for Australian Pet Parents

Welcoming a new kitten? Ensuring they stay healthy starts with the right shots. Discover the core Australian vaccination schedule, understand maternal antibodies, and learn how your vet keeps your playful friend protected against "cat flu" and more.

Author: Dr Brittany Ward BVSc

Reading Time: 13 minutes - short read

Bringing a tiny, purring ball of fluff into your home is one of the most joyful experiences you can have. However, those early months are also when your kitten is most vulnerable to illness. Their little immune systems are still learning the ropes, which is why a structured vaccination plan is so important. Think of it as an essential health shield that guards them against serious, and sometimes fatal, diseases while they grow. By following a clear schedule, you’re not just ticking a box - you’re giving your kitten the freedom to grow, play, and explore their new world safely.

Why kitten vaccinations are essential
Understanding the Australian kitten vaccination schedule
Core vs non-core: what vaccinations does your kitten really need?
The science of maternal antibodies and booster shots
When are non-core vaccinations recommended for outdoor cats?
What to expect during your kitten's vet consultation
Beyond the first year: adult cat booster vaccinations
Common vaccination concerns and side effects explained
Do indoor cats really need to be vaccinated?
FAQs

Why kitten vaccinations are essential

Vaccinations are the most effective way to protect kittens from life-threatening diseases. Because their immune systems are still developing, kittens are especially vulnerable to infections that an adult cat might handle more easily.

Diseases prevented by core vaccinations

The standard kitten vaccination course (the F3) targets three primary threats:

Feline Calicivirus and Feline Herpesvirus-1: These are common causes of "cat flu". Symptoms often start with sneezing, nasal congestion, and runny eyes, but can progress to:

Painful mouth ulcers
High fever and lethargy
Loss of appetite

Feline Panleukopaenia (Feline Parvovirus): This is a severe, highly contagious disease that attacks rapidly dividing cells, such as those in the bone marrow and gut. It can cause:

Severe vomiting and bloody diarrhoea
A weakened immune system
Sudden death, especially in young kittens

How vaccinations work

A vaccine introduces a tiny, harmless version of a virus to your kitten's body. This "teaches" their immune system how to recognise and fight the virus without actually making them sick. If they encounter the real disease later in life, their body is already prepared to jump into action, either preventing the illness entirely or making the symptoms much milder.

The benefit to the community

Vaccinating your kitten doesn't just protect your own pet; it helps the wider cat population through "herd immunity."

Reducing spread: When at least 70% of cats are vaccinated, the disease has fewer places to hide and spread.
Protecting the vulnerable: This community-wide protection shields cats that cannot be vaccinated, such as those with autoimmune conditions or tiny kittens who are still too young for their first needles.
Human safety: In many parts of the world, vaccinating pets for diseases like Rabies is also a critical step in keeping people safe from zoonotic diseases.

Understanding the Australian kitten vaccination schedule

white kitten with grey patch being held in human hand

Your kitten will typically require a course of 3 vaccinations at the following ages:

6-8 weeks
10-12 weeks
16 weeks or older

Kittens under 6 weeks of age are protected by maternal antibodies. We know that in most kittens maternal protection wanes between 6-16 weeks of age, but cannot determine exactly when this will be in the individual kitten. In order to ensure kittens are protected, the World Small Animal Veterinary Association recommends vaccinating every 2-4 weeks from 6 weeks of age until 16 weeks or older.

Core vs non-core: what vaccinations does your kitten really need?

cat at vets about to receive vaccination

There are three different categories of vaccinations that your cat may be able to receive: Core Vaccinations, Non-Core Vaccinations and Not Recommended. The available vaccinations in each species and country are divided into these three categories depending on how important they are.

Core Vaccinations

Core vaccinations are those that all cats are required to receive irrespective of circumstances or location. These are essential vaccinations that are chosen because they protect cats against severe, life-threatening diseases that are present globally.

There are 3 core vaccinations for cats:

Feline Panleukopaenia (FPV) OR Feline Parvovirus
Feline Calicivirus (FCV)
Feline Herpesvirus-1 (FHV-1) OR Feline Rhinotracheitis Virus

These core vaccinations are combined and administered in a single injection called an F3 Vaccination. The core vaccination is what your kitten will be administered with at their kitten vaccinations.

Rabies vaccination is considered a core vaccination in countries where it is regularly occurring. It is not a core vaccination in Australia, rather it is 'not recommended'. If your kitten, or cat, is moving overseas, you will need to check that country's core vaccination requirements.

Non-Core Vaccinations

Non-core vaccinations are those that are required by cats whose location, environment and lifestyle put them at an increased risk of the disease. These vaccinations are optional, but your vet may recommend them for your cat if they are at risk.

The non-core vaccinations available in Australia are:

Feline Leukaemia Virus (FeLV)
Feline Immunodeficiency Virus (FIV)
Chlamydia felis

If your kitten receives an F4 Vaccination, it will usually involve two vaccinations and one of the above Non-Core Vaccinations will be included with the F3 Core Vaccines. An F5 Vaccination includes both FeLV and FIV.

'Not Recommended' Vaccinations

Vaccines considered 'Not Recommended' are those that are not present in your local area and your kitten is not at risk of. The aim is to provide as few vaccinations as is required, so these vaccinations would be given unnecessarily. As mentioned above, Rabies vaccination is not recommended in Australia as we do not have Rabies in our country.

The science of maternal antibodies and booster shots

Understanding maternal antibodies

Most kittens are born with a natural "starter kit" of protection, but understanding how this wears off is key to timing their vaccinations correctly.

What are maternal antibodies?

When a mother cat (the queen) is vaccinated, or naturally infected with a virus, she develops antibodies - special proteins that recognise and fight off specific viruses. She passes this immunity on to her kittens:

In the womb: Some protection is transferred before birth.
Via milk: The most significant boost comes from the first milk, known as colostrum.

These antibodies circulate in the kitten's blood, protecting them from disease during their first few weeks of life.

The "gap" in protection

While maternal antibodies are great for newborns, they create a unique challenge for vaccinations:

Waning immunity: These natural antibodies don't last forever. They usually begin to fade around 6 weeks of age, leaving the kitten vulnerable.
Vaccine interference: If maternal antibodies are still high, they can actually "neutralise" a vaccine, preventing the kitten's own immune system from learning how to protect itself.
The 20-week window: While most maternal protection is gone by 12 weeks, some kittens keep these antibodies for up to 20 weeks.

Why the three-dose schedule is necessary

Because every kitten is different, there is no way to know exactly when the mother's protection ends without an expensive blood test called a titre test. To ensure every kitten is safe, a series of shots is the most reliable method:

The strategy: Administering vaccines every 2–4 weeks (usually at 8, 12, and 16 weeks) ensures that as soon as the maternal antibodies drop, the vaccine can step in and provide long-term immunity.
Closing the window: This frequent schedule minimises the time your kitten spends without any protection at all.
Individual needs: Some kittens, especially those in high-risk environments or those who started their course very early, may require additional boosters as advised by a veterinarian.

When are non-core vaccinations recommended for outdoor cats?

As mentioned above, non-core vaccinations are those that are only required by cats who are at increased risk of the disease. So how do you know if your kitten is at risk?

Feline Leukaemia Virus (FeLV) vaccination is recommended in kittens less than 1 year old with outdoor access, or exposure to other cats (particularly outdoor cats), in any area where the disease is prevalent. Check with your regular vet if you are living in an area of high prevalence. Any kittens negative for FeLV can be vaccinated with two doses 2-4 weeks apart.

Feline Immunodeficiency Virus (FIV) is transmitted by cat bites. This means outdoor cats and cats in multicat households are most at risk. Cats in areas when FIV is of high prevalence, with outdoor access, should be considered for vaccination. Chat to your vet about prevalence in your local area.

Chlamydia felis vaccination is usually recommended for cats with outdoor access and exposure to other cats. This disease is treatable and non-life threatening, so not all vets will recommend this vaccination.

Learn more in our article all about Feline Immunodeficiency Virus.

What to expect during your kitten's vet consultation

A vaccination visit is much more than just a quick needle. It is a comprehensive health check where your vet ensures your kitten is in peak condition to receive their protection.

The pre-vaccination health check

Before any vaccine is administered, your vet will perform a thorough physical examination. This includes:

Checking vitals: Taking your kitten's temperature and listening to their heart and lungs.
Assessing health status: Ensuring your kitten isn't currently fighting an underlying illness.
Reviewing history: Asking you about their appetite, energy levels, and any changes you've noticed at home.

Why only healthy kittens are vaccinated

It is vital that a kitten is 100% healthy before getting their shots. If a kitten is unwell, a vaccination can be problematic because:

Reduced effectiveness: The immune system is already busy fighting an illness, meaning it won't respond as well to the vaccine, potentially making the shot ineffective.
Worsening symptoms: Diverting the body's resources to respond to a vaccine may make it harder for the kitten to recover from their current sickness.
Increased reaction risk: An already overactive immune system is more likely to have an adverse or anaphylactic reaction to the injection.

A holistic approach to kitten care

Beyond the needle, your vet uses this time to partner with you on all aspects of kitten care including:

Parasite prevention: Tailoring a plan for fleas, ticks, and worms.
Nutrition: Recommending a high-quality, age-appropriate diet to fuel their growth.
Future planning: Discussing the best timing for desexing and microchipping.
Behaviour and training: Offering tips for common kitten quirks like biting, scratching or litter box training.

Creating a tailored vaccination plan

Every kitten's life is different, so your vet will customise a schedule based on their specific needs:

Lifestyle assessment: Determining if they need "non-core" vaccines (like FIV or FeLV) based on whether they will be going outdoors.
Risk factors: Adjusting the frequency of shots - for example, high-risk kittens may need boosters every two weeks.
Medical suitability: Identifying kittens with specific conditions, such as autoimmune issues, who may require a modified approach to immunisation.

Beyond the first year: adult cat booster vaccinations

To protect any kittens that may have still had maternal antibodies by the final vaccination at 16-20 weeks, a 12 month booster vaccination is recommended, unless otherwise advised by your vet. After which, a booster vaccination will be given every 12 months.

Common vaccination concerns and side effects explained

cat laying flat on floor looking at camera

Are vaccinations safe?

Yes, for the majority of cats and kittens, these vaccinations are safe. Products such as these must undergo extensive testing prior to being licensed in order to note common side effects and ensure the vaccine is safe for the majority of cats.

Adverse Reactions

Like any vaccination or treatment, the potential for adverse reactions can occur, however, adverse reactions are rare. It is recommended that Veterinarians report all adverse events and studies have shown that approximately only 0.52% of cats (52 in 10,000) experience side effects from the vaccination.

Most common (due to activation of the immune system):

Lethargy
Slight fever
Mild discomfort

These signs usually resolve within 1-2 days and often considered normal.

Localised swelling - localised to injection site, may be tender and disappears quickly. Shouldn't have signs of inflammation like growth, discharge or heat
Cold-like symptoms - this includes sneezing, coughing and a runny nose
Inappetence - usually only lasts 24 hours

More serious side effects that would warrant a vet visit include:

Vomiting
Diarrhoea
Facial Swelling
Hives
Facial or body itching
Breathing difficulties

These side effects will resolve with treatment by your veterinarian. Adverse reactions are more common in kittens than adults.

FAQs

Setting up your kitten's vaccination schedule is one of the kindest things you can do for your new best friend. While the needles might seem a bit scary, the protection they provide lasts a lifetime. Remember, your local vet is your best partner in this journey, so don't hesitate to chat with them about a plan that suits your kitten's specific lifestyle.

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History

Our experts continually monitor the health and wellness space and we update our articles when new information becomes available.

Tue 30 Dec 2025

Edited by Dr Gillian Hill BVSc (Hons)

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About the Author

Dr Brittany Ward BVSc

Veterinarian

Dr. Brittany graduated from James Cook University in 2019 with a Bachelor of Veterinary Science and started working in her home town in the Wide Bay-Burnett Region. She has always been excited about working in the veterinary industry, but over the last few years has grown especially fond of dog behaviour and training, surgery and orthopaedic disease.