Recent articles from two separate research groups published in Science and Nature Medicine report major breakthroughs in flu vaccine research. The advances could ultimately lead to the holy grail of influenza prevention–a universal flu vaccine.
By conferring immunity against large numbers of flu strains, the new vaccines have the potential to reduce the severity of seasonal flu outbreaks and vastly reduce the risk of novel pandemics. Using the RMS Infectious Disease Model, we calculated that if such vaccines were able to confer immunity to 50% of people globally, the risk of a novel flu pandemic outbreak could be reduced by as much as 75%.
This would be a huge success in reducing the risk of excess mortality events and improving global health. Though I should emphasise that while Edward Jenner invented the smallpox vaccine in 1796, it took until 1980 for smallpox to be eradicated from the wild. Beyond development of effective broad-spectrum vaccines, there is a lot of work to do to make the world safe from flu.
A high proportion of flu victims are the elderly. Significantly reducing deaths from flu would disproportionately reduce old-age mortality. This is particularly interesting; not only is it an important milestone in improving old-age public health, it is also relevant to old-age care and budgeting for retirement too.
Influenza Is The Most Likely Source of Future Pandemic Sickness and Mortality.
In the U.S., in a single flu season, the average number of flu-related deaths is 30-40,000, peaking at 47,000 deaths in previous seasons. This does not take account of the viruses that can cause major pandemics: death tolls in the 1918 “Spanish Flu” event reached as high 50-100 million people worldwide.
Widespread use of a universal vaccine conferring lifelong immunity could eliminate these deaths, making a meaningful contribution to reducing infectious disease mortality.
Structure of influenza, showing hemagglutinin as HA. Source
The marvel of the new vaccines under development is their potential to confer immunity against many strains, including ones that have not yet emerged. They work by using cutting-edge molecular machinery to target the stem of the haemagglutinin protein on the virus’ surface. The vaccines have only been tested on animal models and only on a small scale so far, but have worked well in reducing viral loads and mortality in these tests.
If this breakthrough translates into future vaccines that prove efficacious in clinical trials, these could become immensely powerful in combatting both seasonal flu cases and reducing the likelihood of new flu pandemics.
Today, beyond seasonal flu, there are no vaccines capable of preventing novel flu pandemics. However, the production pipeline for the current seasonal flu vaccine can be put to use in pandemics, with current capacity of pipelines estimated to produce decisive quantities of vaccine within three months of a pandemic outbreak.
As quantified in the RMS Infectious Disease Model, while this current technology has the potential to substantially reduce the total caseload of a pandemic, it is not a panacea. Three months is a relatively long time for highly transmissible viruses, so very large numbers of people could be infected in this interval. Even more infections would happen during the roll-out period before the vaccine has successfully been given to sufficient people to halt the spread. Furthermore, complications could emerge during the production that either mean it takes longer than three months, or that such a vaccine only confers partial immunity.
RMS created the world’s first probabilistic model of pandemic influenza and the first probabilistic model of vaccine development, delivery, and efficacy. The recent breakthroughs in flu vaccine research are welcome news and RMS scientists are closely monitoring the developments.