What to expect in the days after your XBB.1.5 COVID-19 vaccine

In the final months of 2023, Australia experienced a steady increase in COVID-19 hospital admissions. This, paired with a rise in the number of COVID-19 antiviral prescriptions dispensed, led some health experts across the country to declare the ‘eighth COVID-19 wave’ in Australia.

Although the eighth wave has not been as severe as previous COVID-19 waves – largely due to an increased level of immunity gained from COVID-19 vaccination and infection – being up to date on your COVID-19 vaccinations remains the best way to protect yourself from serious COVID-19 infection and illness.

Newly formulated Omicron XBB.1.5 COVID-19 vaccines have been developed to bolster this protection. These vaccines trigger a better immune response against newer Omicron variants, providing more up-to-date, targeted protection.

The XBB.1.5 COVID-19 vaccines are now available and in use in Australia. The following gives more detail on the safety of XBB.1.5 COVID-19 vaccines, who should get a vaccine and what to expect in the days following vaccination.

What is an XBB.1.5 COVID-19 vaccine and how is it different to previous COVID-19 vaccines?

The XBB.1.5 COVID-19 vaccines are monovalent (‘mono’ meaning ‘one’) and are designed against one target: the Omicron XBB.1.5 strain of SARS-CoV-2, the virus that causes COVID-19.

When administered, the vaccines produce antibodies that target the Omicron XBB.1.5 strain more specifically and provide better protection against newer Omicron variants that are circulating in the community.  

Although previous COVID-19 vaccines are targeted at earlier strains that are becoming less prevalent in Australia, they still give strong protection against serious disease. The original COVID-19 vaccines were monovalent and targeted the original Wuhan strain. The most recent COVID-19 vaccines were bivalent (‘bi’ meaning ‘two’) and targeted both the original Wuhan strain and the Omicron BA.1 or the Omicron BA.4/5 variants.

Which XBB.1.5 COVID-19 vaccines are available in Australia and who should get vaccinated?

Recent advice issued by the Australian Technical Advisory Group on Immunisation (ATAGI) indicates that XBB.1.5 vaccines are now preferred over other COVID-19 vaccines for children aged 5 years or older and adults who are currently recommended to receive primary or additional doses of COVID-19 vaccine.

There are currently three XBB.1.5 COVID-19 vaccines approved for use in Australia:

• Paediatric formulation Pfizer monovalent Omicron XBB.1.5 – age 5 to <12 years formulation (light blue cap): Children aged 5–11 years (inclusive) who are eligible for a primary or additional dose can receive the paediatric formulation of the Pfizer XBB.1.5 COVID-19 vaccine.
• Pfizer monovalent Omicron XBB.1.5 – age 12 years and over formulation (dark grey cap): Individuals aged 12 years and over who are eligible for a primary or additional dose can receive the Pfizer XBB.1.5 COVID-19 vaccine.
• Moderna monovalent Omicron XBB.1.5 – registered for use in individuals aged 12 years and over: Individuals aged 12 years and over who are eligible for a primary or additional dose can receive the Moderna XBB.1.5 COVID-19 vaccine.

What should I expect in the days following my XBB.1.5 COVID-19 vaccination?

Like most medicines used in health care, the XBB.1.5 COVID-19 vaccines can cause mild side effects that usually resolve on their own within a couple of days. Health professionals call these side effects ‘adverse events following immunisation’ (or ‘AEFI’).

Early data from AusVaxSafety show most individuals who received an XBB.1.5 COVID-19 vaccine experienced no side effects in the first three days following vaccination. In those who did experience a side effect, local reaction – pain, redness, swelling and itching at the injection site – was the most common, followed by fatigue, muscle/joint pain and headache.

AusVaxSafety has been actively monitoring the safety and side effect profiles of the XBB.1.5 COVID-19 vaccines since the vaccines were introduced for use in Australia in late 2023.

AusVaxSafety data give individuals an idea of what to expect following their XBB.1.5 vaccine and can help individuals to plan for vaccination. For example, since a local reaction at the injection site is the most common side effect following XBB.1.5 COVID-19 vaccination, an individual may choose to book their vaccination at a time where they don’t have to play sport the next day.

Pfizer XBB.1.5 COVID-19 vaccine short-term side effect profile

Almost three-quarters of Pfizer XBB.1.5 COVID-19 vaccine recipients (73%) experienced no side effects in the first three days following vaccination. In those who did experience a side effect, local reaction – pain, redness, swelling and itching at the injection site – was the most common, followed by fatigue, muscle/joint pain and headache.

The level of impact on routine activities was low, with only 4% of respondents reporting missing work, study or routine duties in the three days after vaccination. Reported medical attendance rates also remained low at 0.3%.

Moderna XBB.1.5 COVID-19 vaccine short-term side effect profile

More than half of Moderna XBB.1.5 COVID-19 vaccine recipients (54%) experienced no side effects in the first three days following vaccination. In those who did experience a side effect, local reaction – pain, redness, swelling and itching at the injection site – was the most common, followed by fatigue, muscle/joint pain and headache.

The level of impact on routine activities was low, with 9% of respondents reporting missing work, study or routine duties in the three days after vaccination. Reported medical attendance rates also remained low at 0.4%.

How does the side effect profile compare to previous COVID-19 vaccines?

Early data indicate that Pfizer XBB.1.5 and Moderna XBB.1.5 COVID-19 vaccines are tolerated as well as the original and bivalent Moderna and Pfizer COVID-19 vaccines. AusVaxSafety participants reported similar rates of side effects, medical attendance and impact on routine activities following XBB.1.5 COVID-19 vaccination compared to previous COVID-19 vaccinations.

What is being done to monitor the safety of XBB.1.5 COVID-19 vaccines in Australia?

Australia has one of the most robust vaccine safety monitoring systems in the world. The Therapeutic Goods Administration (TGA) will be monitoring any reports of serious AEFI following XBB.1.5 COVID-19 vaccination via its passive reporting system.

AusVaxSafety is also actively monitoring the adverse event profile and safety of Pfizer and Moderna XBB.1.5 COVID-19 vaccines to ensure they are performing as safely as expected in real-world conditions.

XBB.1.5 COVID-19 vaccine safety data are updated on the AusVaxSafety website monthly.

Access Pfizer XBB.1.5 COVID-19 vaccine safety data here

Access Moderna XBB.1.5 COVID-19 vaccine safety data here