When a child is vaccinated against measles, she becomes immune for many years to come – hopefully the rest of her life. The body creates an immune response to the killed viruses in the vaccine and remembers it.
– That's what the immune system's genius is. As long as the infection does not change all the time, we have a stockpile of defense equipment ready to knock it down the next time it arrives, says Olav Hungnes, senior researcher at the Institute of Public Health and head of the National Influenza Center.  – That's why childhood illnesses are childhood illnesses. Because if they try again, they are rejected at the door, Hungnes continues.
But with the flu, it's different.
The disease is not as dangerous as measles, but seasonal flu also takes life. This is especially true for elderly and other vulnerable persons: Every year, about 900 people die from the disease.
So why do those who want to protect themselves against influenza take a new vaccine every year?
And what does it take to get a universal flu vaccine that protects against flu for life?
He is one of many scientists around the world researching a universal flu vaccine. than we do today.
Virus from patients Kansas and Phuket
Today's flu vaccine is the result of a laborious international collaboration between government and pharmaceutical companies.
Inside the vaccine, the virus kills ordinary patients from around the world. The vaccine for the 2019/2020 flu season contains viruses that originally came from four patients in Brisbane, Kansas, Colorado and Phuket, respectively.
The reason why they were chosen is about the properties that researchers are looking for in the viruses that will turn into vaccines.
Because there are different groups of influenza viruses, and each season the vaccine contains dead viruses from three to four of these groups.
And since the viruses mutate so much, there are also different virus strains within each group. The researchers' task is to predict which virus strains they believe will infect most of the next flu season.
– Every season we have to make the best assessment of which virus strains are emerging and which can be a good candidate for vaccine, says Hungnes
It is the Institute of Public Health that keeps track of the influenza viruses that people are infected with in Norway . Hungnes himself has twice participated in the international meetings organized by WHO, which decide which viruses will be included in next season's influenza vaccine.
But this decision must be made long before the flu season begins. Because it is vaccine production itself that takes the longest time.
And since viruses only multiply inside living cells, the way the vaccines are produced may be a little surprising to many.
– It usually takes at least half a year. This is because the virus must be grown in eggs, and it is a long and complicated process, says Bogen.
The eggs that the virus reproduces inside are common chicken eggs that have been fertilized.
Before the virus from the eggs ends up in the vaccine, they are killed or inactivated with chemicals.
Much can be changed
And then just cross your fingers to give the vaccine good protection. Too much may have changed during the production months:
- Other variants of influenza viruses may have become dominant among humans.
- The actual flu virus may have mutated so much that the vaccine does not provide protection. may have changed in the laboratory during production.
So the virus mutates so easily is a big problem.
– Not only do they mutate in the human body, but they can also mutate when you make them in chicken eggs, the book says.
If the viruses in the vaccine are different from those you are infected with, your immune system may not recognize them.
Aims for spikes on the surface
But if the virus changes so much all the time, it sounds hopeless to make a lifelong flu vaccine. Or?
The book believes that the key to a universal flu vaccine lies on the surface of the virus.
There are some proteins that act as nails that attach to our cells. It is these nails, called hemagglutinin, that our immune system recognizes.
But when the virus mutates, these spikes can change so much that they can attack our cells undetected.
Many of the researchers are trying to make a new flu vaccine trying to focus our immune system on these nails. So instead of injecting all or a large part of the virus into the body, we can be satisfied with hemagglutinin.
How the book and colleagues do this is to create a DNA piece containing the recipe for different variants of the spiked surface protein.
The idea is that you can get this as a so-called DNA vaccine.
Then your body creates the substances that the immune system will learn to recognize.
The researchers have tested such a DNA vaccine in mice. It contains the recipe for seven variants of hemagglutinin. Now they test vaccines with up to 18 different variants of the surface protein.
– The hope is that if we make such immune responses very broad, you will be protected from new variants, Bogen explains.
The next step is to test the vaccine against humans.
But why not just include even more variants of the flu virus in the vaccine we do today?
Probably it wouldn't work, Hungnes responds.
– It is demanding to produce an annual updated vaccine with four strains for six months from the strains determined for the vaccine to be ready. And we don't know how useful it would be for the immune response to get a jumble of related virus variants in the yard at the same time.
Attacking Points That Don't Change
Another strategy for creating a universal flu vaccine is to concentrate on one or a smaller portion of the virus. Because on the otherwise variable surface proteins, there are some areas that do not change much. Hungnes explains:
– Some parts of the protein are similar to other viruses because they tolerate minor changes. Going for these parts may be closer to the holy grail, which is the universal flu vaccine, says the senior researcher.
The US National Institute of Health (NIH) is testing a vaccine against people with this strategy. The vaccine contains a small portion of the spiked surface protein – which just doesn't change when the virus mutates.
What strategy: It is not easy to make a universal flu vaccine.
Some of the problem with these new vaccines is that they have failed to trigger a sufficiently strong immune response in the recipient of the vaccine.
A new flu vaccine that provides lasting protection is therefore hardly just around the corner.
– This will take a long time. We are at the beginning of this here, confirms the book.
But the benefits are many if researchers find a new way to make the vaccines. The production of these new vaccines will potentially be much faster than today's vaccine production.
Not only has there been good news for vulnerable groups taking the flu vaccine every year. When the next big pandemic comes, more of us can become impatient after receiving a vaccine.
– If it becomes a really serious pandemic, it is a big problem that with today's technology you will first have enough vaccine for a 6-8 months. This was the case with the Mexican swine flu, the book concludes. 2018, https://doi.org/10.4049/jimmunol.1701088ebrit19659066??Read also:
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