The Australian Influenza Vaccine Committee (AIVC) has recently announced the composition of the 2024 flu vaccination.
Each year, the composition of the vaccine changes, to take into account a number of factors, including the recent strains of influenza circulating in Australia and the Southern Hemisphere. We thought this was a good time to delve into the reasons behind this ever-changing flu vaccine, and why it’s essential to keep up with the flu virus’s shapeshifting nature.
Influenza: A Mutating Virus
Influenza is caused by the influenza virus, a pathogen notorious for its ability to mutate rapidly. There are three main types of influenza viruses: A, B, and C, with influenza A and B being the primary culprits responsible for seasonal flu epidemics. These viruses mutate constantly, which makes it challenging for the immune system to recognize and combat the virus effectively.
Antigenic Drift and Shift
The two main mechanisms by which the flu virus changes are known as antigenic drift and antigenic shift:
Antigenic Drift: This is a gradual process in which small changes accumulate in the virus over time. These minor mutations are responsible for the seasonal variation in the flu virus. As a result, the immunity gained from previous infections or vaccinations may not be as effective against the new strains, necessitating yearly updates to the flu vaccine.
Antigenic Shift: This is a more significant and sudden change that occurs when different strains of the virus combine or reassort. Antigenic shifts can lead to the emergence of entirely new flu viruses that the human population has little to no immunity against. Fortunately, these shifts are less common but are the main cause of flu pandemics.
Surveillance and Predicting the Flu Strains
To stay ahead of the ever-changing flu virus, scientists and public health agencies engage in active surveillance. They monitor the prevalence of different flu strains worldwide, collecting data on which strains are circulating and evolving. This surveillance informs the World Health Organization (WHO) and other health agencies to make predictions about which strains are most likely to dominate in the upcoming flu season.
Preparing the Annual Flu Vaccine
Based on the data gathered from surveillance efforts, researchers make informed decisions about the composition of the annual flu vaccine. They select the most prevalent and potentially dangerous strains expected to circulate in the coming season. This process occurs months before the flu season begins, allowing time for the production and distribution of the vaccine.
Herd Immunity and Public Health
The annual change in the flu vaccine is essential for maintaining herd immunity, which is the collective immunity of a population. Herd immunity helps protect those who are most vulnerable to severe illness, such as young children, the elderly, and individuals with compromised immune systems. To maintain this protective shield, it’s necessary to adapt the flu vaccine to the evolving flu virus strains.
Staying on guard against the flu
The ever-changing nature of the flu vaccine is a direct response to the remarkable adaptability of the influenza virus. Antigenic drift and shift ensure that the flu is a persistent and formidable threat to public health. By updating the flu vaccine each year, scientists and healthcare professionals aim to provide the best possible protection to the population. Staying informed and getting vaccinated annually is one of the most effective ways to reduce the impact of the flu and help safeguard public health.
Composition of 2024 Flu Vaccine
For 2024, two (2) new strains have been included in the 2024 flu vaccine:
- an A/Victoria/4897/2022 (H1N1) pdm09-like virus (New strain for 2024)
- an A/Thailand/8/2022 (H3N2)-like virus (New strain for 2024)
- a B/Austria/1359417/2021 (B/Victoria lineage)-like virus
- a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.
We would love to help you protect your workforce against the flu in 2024. Request a quote or contact us today.
