What makes the influenza vaccine effective against a continuously changing virus?

The influenza (flu) vaccine has been around since 1945 – that’s nearly 80 years!1 However, it’s not the same vaccine that was introduced in 1945; to ensure that it is effective against a continuously changing virus, new flu vaccines have to be developed regularly.1

Regular updates and careful monitoring are key to the flu vaccine’s efficacy

While the first flu vaccine was introduced in 1945, researchers soon realised that it was ineffective against the flu viruses circulating in 1947.1 Since then, the Worldwide Influenza Centre and the Global Influenza Surveillance and Response System (GISRS) was established by the World Health Organization (WHO) to monitor the influenza virus strains in circulation around the world.1

Using this information, the WHO predicts the virus strains that are likely to be the most dominant for each hemisphere.1 These virus strains are then included in the development of the latest flu vaccines so that they can effectively target the strain predicted to be circulating in the coming season.1

Why is it important to have an annual flu vaccine?

Flu has been responsible for some of the deadliest pandemics in history.2-5 We still talk about the 1918 ‘Spanish flu’ pandemic, which was estimated to have infected one-third of the global population and killed approximately 50-100 million people worldwide.2 Subsequent pandemics such as the Asian flu pandemic (1957),3 the Hong Kong flu pandemic (1968)4 and the swine flu pandemic (2009)5 also resulted in millions of deaths.3-5

Today, there are an estimated 1 billion cases of flu each year globally.6 While seasonal vaccines have been largely effective in managing the severity of the virus, there are still 3 to 5 million severe cases every year, resulting in up to 650,000 deaths annually.6 Those who are particularly vulnerable to the virus include pregnant and post-partum individuals, people living with chronic health conditions, the elderly, and children under 59 months of age.7

In Italy, seasonal flu vaccination is recommended and offered actively and free of charge for most of these demographics, as well as to those working in public services: doctors and healthcare personnel, police forces, the fire brigade and more.8

A universal flu vaccine could soon be the way forward

Scientists are working on a universal flu vaccine that has the potential to change the way we protect ourselves against the disease.9 This vaccine would aim to broaden our immune response by including all strains or subtypes within an influenza group, with the ultimate goal to elicit lifelong immunity against the flu.9

While this is an important goal, it is an enormous challenge. In the meantime, researchers, scientists and manufacturers are working hard to improve the immediate future of flu vaccines. One of the ways they’re doing so is by harnessing next generation sequencing and genomic technologies to develop better flu candidate vaccine viruses that can be used by vaccine manufacturers to produce flu vaccines.10

More information

If you have any questions about the flu vaccine and if you are considering being vaccinated, please speak to your doctor or healthcare professional.

Dirk Poelaert of Novavax
Dirk Poelaert, MD
Senior Director, Medical Affairs

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  1. History of the Influenza Vaccine. WHO 2023. Available at https://www.who.int/news-room/spotlight/history-of-vaccination/history-of-influenza-vaccination [Accessed 7 Sept 2023].
  2. Nickol ME, Kindrachuk J. BMC Infect Dis. 2019;19:117.
  3. 1957 Flu Pandemic. Britannica 2020. Available at https://www.britannica.com/event/1957-flu-pandemic [Accessed 7 Sept 2023].
  4. 1968 Flu Pandemic. Britannica 2020. Available at https://www.britannica.com/event/1968-flu-pandemic [Accessed 7 Sept 2023].
  5. Hajjar SA, McIntosh K. Ann Saudi Med. 2010;30:1–10.
  6. WHO Launches New Global Influenza Strategy. WHO 2019. Available at: https://www.who.int/news/item/11-03-2019-who-launches-new-global-influenza-strategy [Last accessed 7 Sept 2023].
  7. Influenza (Seasonal). WHO 2023. Available at https://www.who.int/news-room/fact-sheets/detail/influenza-(seasonal) [Accessed 7 Sept 2023].
  8. Categories for Which Vaccination is Recommended. Istituto Superiore di Sanità EpiCentro – Epidemiology for Public Health 2023. Available at https://www.epicentro.iss.it/influenza/categorie [Accessed 7 Sept 2023].
  9. Chen J-R, et al. J Biomed Sci. 2020;27:33.
  10. Flu Vaccine Advancements. CDC 2022. Available at https://www.cdc.gov/flu/prevent/advances.htm#:~:text=an%20intradermal%20vaccine%20that%20requires,from%20this%20published%20article)%3B [Accessed 7 Sept 2023].