For most adults, if it has been six months since you had COVID or your last vaccination, you're likely eligible to book in your next dose.

Meanwhile, the flu vaccine is recommended for everyone over the age of six months.

But can you get both at once? Yes, you can get your flu vaccine and COVID booster safely at the same time, saving you a trip to the GP, nurse or pharmacy.

When COVID vaccines were first rolled out, a gap was recommended between COVID and flu vaccines. This is because we didn't have adequate data of the individual and long-term effects of the new COVID vaccines.

After examining the latest available evidence on safety and efficacy, the World Health Organization updated its interim guidelines. It suggests getting an influenza vaccine and any dose of any approved COVID vaccine at the same time is a practical option.

However, until more data becomes available, the WHO advises using different arms for vaccination. This is to prevent the ingredients of the vaccines mixing and to limit the initial immune response to a different group of lymph nodes.

The Australian Technical Advisory Group on Immunisation updated its vaccination guidelines in March 2022, advising that influenza and COVID vaccines can be administered on the same day.

Getting multiple vaccinations at once isn't new. Childhood vaccinations are routinely and safely administered at the same time.

For COVID and flu vaccines, randomised controlled trials show no significant difference in the immune responses of the people who had both vaccines at once compared to those who had them on different days.

Participants who had both vaccines at once reported the same types of side effects from the body's inflammatory response to vaccination (injection-site pain, redness, swelling at the injection site) as well as general symptoms associated with both COVID and flu vaccines, such as fever, muscle pain and a headache.

These minor side-effects were of similar intensity and duration to those who had either vaccine administered alone.

Getting both COVID and flu vaccines is also more cost-effective, the uptake is higher when people don't have to make multiple trips, and it saves health practitioners' time.

Although simultaneous infections with two different viruses are common, SARS-CoV-2 has been infecting humans for a relatively short time. We therefore have limited data on how influenza strains and SARS-CoV-2 interact with the host at the same time, and if there is any interaction between the viruses.

However, one large study in England reported that people positive for influenza had lower odds of also testing positive for SARS-CoV-2. This was attributed to possible cross-reactive immunity between viruses.

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It did, however, find people infected with both viruses at the same time had worse outcomes and were twice as likely to die as those who were only infected with SARS-CoV-2.

Some experimental evidence suggested prior infection with type A influenza virus promotes SARS-CoV-2 entry and infectiousness. This could be due to a unique feature of the influenza A virus which allows COVID to take hold more easily.

Influenza and COVID vaccines are available at GP clinics and pharmacies.

Australians aged five years and over are eligible for a free COVID vaccination. The flu vaccine is free for people at higher risk of complications, including:

For the rest of the population, the flu vaccine costs around A$20-30. Some practitioners also charge a consultation fee.