As the flu season approaches in Australia, new flu vaccines for 2025 have become available. Many individuals have likely received notifications from their healthcare providers regarding the stock of these vaccines.

In the early months of 2025, Australia has observed an uptick in flu notifications compared to previous years. Additionally, numerous countries in the northern hemisphere have reported significant flu activity during the 2024-2025 winter season, which has tragically resulted in several fatalities among children. While predicting the severity and timing of the upcoming flu season is challenging, now is an opportune moment to consider vaccination.

Who Should Receive the Vaccine and When?

In Australia, flu vaccines are accessible to everyone aged six months and older. While flu vaccines are less effective in very young infants, maternal immunization during pregnancy can provide necessary protection. The National Immunization Program offers free vaccines to individuals considered at higher risk, including seniors over 65, children aged six months to five years, pregnant women, and Aboriginal and Torres Strait Islander populations.

For healthy adults and children outside these high-risk groups, the cost of a flu vaccine ranges from A$20 to A$30. These vaccines are widely available through general practitioners, pharmacies, and workplace programs. Vaccination can reduce the likelihood of visiting a healthcare provider for influenza by approximately 30% to 60% and decrease hospitalization risk by about 50% to 70%.

It is important to note that the effectiveness of flu vaccines may diminish over time. Ideally, vaccinations should be administered a few months before the peak flu season, but predicting this peak can be difficult, especially since flu seasons have started earlier than usual in the aftermath of the COVID-19 pandemic. Therefore, getting vaccinated within the next month is advisable.

Flu vaccines can generally be given simultaneously with most other vaccines, including COVID-19 vaccines, although individuals should consult their vaccination provider for personalized advice. Flu vaccines are regarded as safe; while some recipients may experience mild side effects such as soreness at the injection site or low-grade fever, serious complications like Guillain-Barré syndrome are rare and occur less frequently than complications from actual influenza infection.

Why Annual Vaccination is Essential

Influenza is a complex virus, making the development of vaccines a challenging task due to its frequent mutations. Studies indicate that the rate of mutations in the influenza virus is significantly higher than that of SARS-CoV-2, the virus responsible for COVID-19. As a result, health experts must make educated predictions about which strains are likely to circulate in the upcoming season, allowing for timely vaccine production.

The World Health Organization holds two key meetings annually: one in February to select the strains for the northern hemisphere's vaccine, and another in September for the southern hemisphere. Current influenza vaccines typically contain strains from four key subtypes: A/H1N1, A/H3N2, B Victoria, and B Yamagata, although it is anticipated that the B Yamagata strain may be omitted in future vaccines due to its decreased prevalence since the pandemic.

It is essential to note that seasonal flu vaccines do not protect against avian influenza (bird flu), although vaccination is still recommended for individuals at risk, such as poultry workers, to minimize the potential for new virus combinations.

Available Vaccine Options

When scheduling a flu vaccination, individuals may be presented with various vaccine options. Recent years have seen the introduction of new vaccine types aimed at enhancing immune responses. For instance, Fluad Quad contains an adjuvant known as MF59, which helps attract immune cells to the vaccination site. Other vaccines, like Fluzone High-Dose, utilize a higher dosage of vaccine strains to bolster immune responses, particularly in older adults whose immune systems may be less robust.

Some vaccines also employ alternative production methods to ensure a better match between the vaccine strains and circulating strains. Traditional flu vaccines are often made using influenza viruses cultivated in chicken eggs, which can lead to viral mutations during production, known as "egg adaptation," and can sometimes diminish vaccine effectiveness. In contrast, cell-based vaccines like Flucelvax Quad use mammalian cells for virus cultivation, reducing this risk.

Key takeaways include:

• Older adults are advised to receive enhanced vaccines, such as Fluad Quad for those aged over 65 or Fluzone High-Dose for those over 60, with Fluad Quad available for free under the National Immunization Program.
• Other individuals are encouraged to opt for standard vaccines (either egg-based or cell-based), with free vaccinations provided for high-risk groups and children aged six months to five years.

Looking Ahead

Several innovative flu vaccines are currently in development. Recombinant vaccines like Flublok utilize insect cells to produce specific virus components. The success of mRNA technology in COVID-19 vaccines has spurred interest in applying similar methods for influenza vaccines, potentially streamlining the vaccine development process for both seasonal and pandemic influenza. There is also growing interest in combination vaccines that could simultaneously protect against both COVID and influenza.

While the quest for a universally effective influenza vaccine continues, receiving a flu shot significantly reduces the risk of influenza and its associated complications.