By Estanislao Nistal Villán and Javier Arranz Herrero
The 1918 Spanish flu pandemic was caused by a particularly virulent strain of influenza virus. It infected 500 million people, caused around 50 million deaths, and its impact was so severe that global life expectancy fell dramatically. It claimed more lives than the First World War.
In their efforts to develop a vaccine, researchers at the time worked under the mistaken assumption that influenza was caused by bacteria, based on Richard Pfeiffer’s 1892 discovery of the “bacillus influenzae”, which today is known as the bacterium Haemophilus influenzae.
It was not until 1931 that Richard Shope discovered the Influenza A virus in pigs. In 1933, Wilson Smith, Christopher Andrewes and Patrick Laidlaw then discovered the same virus in humans.
Subsequent work has described different versions of the virus surface proteins haemagglutinin (HA) and neuraminidase (NA). Different combinations of these give rise to the influenza A virus subtypes, including the H1N1, H2N2 and H3N2 subtypes that have afflicted humankind for over 100 years.
The first inactivated influenza vaccine for use in humans was developed by Thomas Francis (who also developed the Influenza B virus in 1940) and his student Jonas Salk, who later developed the polio vaccine.
The influenza vaccine was tested for safety and efficacy in the US military during World War II before being licensed for wider use in 1945. However, researchers soon realised that the virus regularly mutated, meaning vaccines needed annual updates to remain effective.
Constant evolution
Various technologies and methods are used in producing flu vaccines. In the northern hemisphere, design for the autumn vaccine begins in February, and is based on the strains circulating at that time.
Over recent decades, vaccines have evolved in response to changes in circulating viruses. In 1948, the World Health Organization (WHO) established the Global Influenza Programme and, in 1952, the Global Influenza Surveillance and Response System (GISRS) to track emerging strains.
These initiatives enabled the production of seasonally updated vaccines, and form the basis for the WHO’s annual recommendation of specific strains to be included in each hemisphere’s immunisations against Influenza A H1N1 and H3N2, as well as Influenza B viruses.
Flu returns annually as an epidemic. It is a constant threat to public health, affecting millions of people and causing severe complications in the most vulnerable: young children, older adults, and people with pre-existing conditions.
How effective are vaccines?
In 2010, the recommendation for full vaccination of the population (from 6 months onwards) marked a major advance in reducing the risk and complications of infection. It also meant that hospitals were under less strain in the winter months. Since then, flu’s impact has diminished greatly, but what do we really know about how effective vaccines are?
To find out, our team conducted a study. We analysed different parameters to estimate the effectiveness of influenza vaccination in preventing and reducing the severity and mortality of infection, especially in the most vulnerable segments of the population.
Our work is a meta-analysis of 119 articles published over the last 10 years, covering a total of 192,705 patients. Our mathematical analysis was validated using data from the TrinetX database, which includes over 6.5 million patients.
We analysed the percentage of the most common influenza viruses such as Influenza A (H1N1 and H3N2) and Influenza B in different age groups: children under 5, people between 5 and 65, and people over 65. In addition, we studied the effectiveness of vaccines against these viruses in the same age groups.
Our results show that vaccines are effective in preventing infection with the different influenza viruses they are intended to prevent. In the case of H3N2, this protection is more limited.
In terms of its effectiveness in preventing deaths, our analysis of the data shows that influenza vaccination is able to reduce infection-associated mortality by half overall, including H3N2 infections.
For at-risk groups – those with pre-existing conditions that make them two to ten times more likely to die after influenza infection – vaccination in some cases reduced their mortality to levels comparable to those of uninfected people. This highlights the vaccine’s ability to protect even those who face the greatest risks.
It’s a fact: vaccines save lives
In a society where vaccine scepticism is on the rise, it is crucial that we gather and analyse all available evidence, share it, and use it to make objective decisions that outweigh opinions or value judgements.
It is true that vaccination does not guarantee that nobody will get infected. However, it does reduce the burden of disease on healthcare systems and, more importantly, it saves lives. Mild or moderate symptoms after infection are a small price to pay when you consider that vaccines protect us from hospitalisation, serious complications and death.
We often hear people say things like “I got vaccinated this year and still got the flu”. However, with the data in front of us, we can be certain that without vaccination, this illness could have been much, much worse.
Estanislao Nistal Villán is Virologist and professor of Microbiology at the Faculty of Pharmacy, CEU San Pablo University, Javier Arranz Herrero is a doctoral student at CEU San Pablo University, PFIS at the Carlos III Health Institute and Visitor Researcher at Mount Sinai, NY, CEU San Pablo University.
Thomas Hutson says
Hey now watch what you say! That whack job Kennedy just might hear you. Maybe if he had some vaccine shots he might not have had worms in the brain.
Jim says
There is no reason to be alarmed! We’ve got Donald Trump in office! The Make America Great Again President. He’s got our best interests at heart so he won’t do anything to impact any risks we might have of viruses, right? (Right???). Well, okay, he did fire the folks that are investigating the bird flu virus and checking for mutations and such but, hey, ya gotta break a few eggs to make an omelet (Google John Kennedy from LA; he likes omelets better than sex!)!! And we’ve got Robert Kennedy running Health and Human Services! There’s a guy who knows everything about vaccines and virtually any other health or eating subjects you might bring to his attention! Here’s the guy who cut the head off a whale and took it home; a guy who dumped a dead bear in Central Park for the fun of it! Here’s a guy who is against vaccines leading the department! What do we have to worry about??
I haven’t had the flu in nearly 20 years and I attribute a lot of that to getting the flu shot every year. But next year? Hey, like everyone else, I’ll be on my own and hoping for the best.
You gotta love MAGA land. Things are getting so great so fast that it makes my head spin!!!!
Craig says
There’s no way them shots prevented anything. Each shot is for the flu strain the previous year. It’s non effective cuz the strain changes every year. Also do you what in them shots? Different DNA of animals, instead believing propaganda and hit pieces maybe you should look up the info and what you are outting in your veins. There is a reason those companies get immunity from the govt. They were fetting sued left and right before they got immunity. Facts are strange things compared to the lies and propaganda they pay to tell you.