Public healthInfluenza: The search for a universal vaccine
No one wants to catch the flu, and the best line of defense is the seasonal influenza vaccine. But producing an effective annual flu shot relies on accurately predicting which flu strains are most likely to infect the population in any given season. It requires the coordination of multiple health centers around the globe as the virus travels from region to region. Once epidemiologists settle on target flu strains, vaccine production shifts into high gear; it takes approximately six months to generate the more than 150 million injectible doses necessary for the American population. With current technology, there may never be a “one and done” flu shot. And epidemiological surveillance will always be necessary. However, it is not inconceivable that we can move from a once-per-year model to a once-every-10-years approach, and we may be within just a few years of being there.
No one wants to catch the flu, and the best line of defense is the seasonal influenza vaccine. But producing an effective annual flu shot relies on accurately predicting which flu strains are most likely to infect the population in any given season. It requires the coordination of multiple health centers around the globe as the virus travels from region to region. Once epidemiologists settle on target flu strains, vaccine production shifts into high gear; it takes approximately six months to generate the more than 150 million injectible doses necessary for the American population.
Incorrect or incomplete epidemiological forecasting can have major consequences. In 2009, while manufacturers, including MedImmune and Sanofi Pasteur, were preparing vaccines against the anticipated strains, an additional influenza strain, H1N1, emerged. The prepared vaccine didn’t protect against this unanticipated strain, causing worldwide panic and over 18,000 confirmed deaths – likely only a fraction of the true number, estimated to exceed 150,000. Better late than never, a vaccine was eventually produced against H1N1, requiring a second flu shot that year.
Given that influenza has caused the majority of pandemics over the past 100 years – including the 1918 flu that resulted in as many as 50 million deaths – we’re left with the question: Can scientists produce a “universal” vaccine capable of protecting against diverse strains of influenza, one that doesn’t require annual predictions by epidemiologists and a yearly shot for you?
Vaccines prime the immune system to fight
By the 18th century, and arguably much earlier in history, it was commonly known that a survivor of smallpox would not come down with it again upon subsequent exposure. Somehow, infection conferred immunity against the disease. And people recognized that milkmaids who came into contact with cowpox-ridden cattle would similarly be protected from smallpox.
In the late 1700s, farmer Benjamin Jesty inoculated his family with cowpox, effectively immunizing them against smallpox, despite future exposure. Physician Edward Jenner then catapulted humanity into a new age of immunology when he lent scientific credence to the procedure.
So if one inoculation of cowpox or one exposure to (and survival of) smallpox confers a decade’s-worth or even lifelong immunity, why are individuals encouraged to receive the flu vaccine every year?
