The Search for a Universal Flu Vaccine to prevent the next pandemic
Online science editor Daisy Scott discusses the impact of seasonal influenza recent research into the possibility of a Universal Flu Vaccine and the challenges involved with this research.
Even though we are all fed up with the social distancing and mask wearing that has ruled our lives for the last 20 months with COVID-19, the next pandemic poses an ever-present threat and could be just around the corner. Dr. Wenqing Zhang, the manager of WHO’s Global Influenza Programme has said “another pandemic caused by a new influenza virus is a certainty. But we do not know when it will happen, what virus strain it will be and how severe the disease will be”.
Looking at the impact of previous influenza pandemics, developing a universal flu vaccine to protect against a variety of strains is more important than ever. However, this development is made much more difficult by the fact that the influenza virus is constantly mutating to evade the best efforts of our immune systems.
Influenza is still not thought of by many people as a serious illness with a substantial mortality – a 2017 study found that worldwide up to 650,000 people died of influenza-associated disease, and up to 72,000 of these deaths occur in Europe.
A 2017 study found that worldwide up to 650,000 people died of influenza-associated disease
Influenza is not thought of by many as a serious illness, although it kills up to 650,000 people each year. The common flu virus exists in many types and subtypes: both influenza A & B can cause epidemic seasonal infections. Influenza B is typically only found in humans, but Influenza A serotypes are found in many other species and if these subtypes transfer to humans, the risk of a pandemic increases. Influenza viruses are named after the 18 possible HA serotypes and 11 different subtypes of neuraminidase. The subtypes most found in humans are H1N1 or H3N2.
There have been 3 major worldwide influenza pandemics since 1918 –
- 1918 Spanish Flu – H1N1 with genes of avian origin – It is considered the most lethal pandemics in history as it infected 500 million people (~1/3 of the worlds population) and killed an estimated 50 million people.
- 1957 Asian Flu – H2N2 that originated from an avian influenza A virus. The estimated death toll from this was estimated at 1.1 million worldwide.
- 1968 Hong Kong Flu – H3N2 comprised genes from an avian influenza A virus but also contained components of H2N2 virus. The estimated number of deaths was 1 million people worldwide. This H3N2 virus continues to circulate worldwide as a seasonal influenza A virus.
The challenge with creating a universal vaccine for the influenza virus is that it can alter its surface protein. Sunetra Gupta, a theoretical epidemiologist and vaccine developer from University of Oxford has said “it is engaged in a kind of evolutionary process that one could describe as an arms race”.
One of the most promising approaches currently in use involves stimulating immunity against the parts of the mushroom-shaped HA protein that remain unchanged across several strains – specifically the “stalk” of the mushroom rather than the “head”.
In recent years, there have been several companies who have tried to develop a universal vaccine which have all failed –
- In January 2020, Oxford-based biotechnology company Vaccitech announced that phase IIb data for their VTP100 vaccine had shown it had not achieved reductions in infections compared with its seasonal vaccine.
- In October 2020, after 15 years of research, Israeli Biotech company BiondVax pharmaceuticals announced their phase III study of the M001 vaccine demonstrated no significant protection against placebo.
Although there have been recent successful steps for the use of a universal vaccine since in 2020, US vaccine development company Novavax started a phase II trial for its quadrivalent NanoFlu, although it was not universal since it only showed “significant improvements against four drifted H3N2 strains”.
You will never demonstrate universality because you don’t know what’s coming next year
A truly universal vaccine would protect against any new subtypes that may emerge from the animal kingdom – sometimes called an “antigenic shift” – which is much more difficult. However, Olga Pleguezuelos, chief scientific officer of biotech company ConserV Bioscience has said “You will never demonstrate universality because you don’t know what’s coming next year.”