Why the flu shot must be given every year, Digi Mart USA News: People at increased risk of influenza line up for a flu shot every year. Why is this necessary, and could these people not receive a single shot, as with other vaccinations?
The flu season has begun, so the flu shot is available for people at increased risk of influenza, for example because of an existing illness or their age. The annual shot is meant to prevent a seasonal illness that could be serious for them.
But why must they be vaccinated again every year? Could this not be done more efficiently?
To understand this, one must first understand how the flu vaccine is made. The classic and cheapest method is to inject fertilized chicken eggs with the virus.
Each year the World Health Organization determines which strain or strains of the influenza virus are expected to be active in the coming flu season, and manufacturers use those strains.
A fertilized egg contains living cells in which the virus multiplies. After several days in an incubator, the manufacturer extracts the fluid from the egg.
This fluid is purified and heated so the vaccine keeps longer. What remains is a fluid containing the outer proteins of the flu virus.
Each egg yields one flu shot. The immune system recognizes these outer proteins and produces antibodies against them.
You do not become ill from it, but you are protected if you later come into contact with the virus.
Protected, though? That could be better, according to the U.S.
Centers for Disease Control and Prevention (CDC). Over the past ten years, the effectiveness of the flu vaccine has ranged between 20 and 60 percent.
That means that despite a shot, you still have a considerable chance of catching the flu, and after a few months you also need a new shot.
“If you could vaccinate with the purified fluid, directly from the egg, an annual flu vaccination campaign would not be necessary,” says Ed Schmidt, project manager for pandemic preparedness at the LUMC. The molecular cell biologist has been involved in international vaccination projects for more than twenty years, including a project for a new generation of flu vaccines.
“Heating reduces effectiveness,” Schmidt explains. “That heating is needed for shelf life and to limit side effects.
But in effect, the manufacturer deliberately cooks it to destruction.”
There are now other ways to make vaccines besides using eggs. Some vaccines come from cell cultures, in which the virus is grown in animal cells in the laboratory.
There are also so-called epitope vaccines, which contain only a small synthetic fragment of a virus or bacterium. And what about mRNA vaccines, which prompt our body to produce virus particles?
“We could certainly make better types of vaccines if we wanted to. We saw that a few years ago with the COVID-19 pandemic,” Schmidt says.
“But the production costs of other methods are at least twice as high as the classic method. Manufacturers therefore keep relatively large amounts of money.
The flu shot is big business, and they want to keep it that way.”
In short, vaccine manufacturers have the goose that lays the golden eggs in the annual flu shot, and they have no intention of slaughtering it. Although the European Union has meanwhile launched several large programs to develop a new generation of flu vaccines, for the time being there is nothing to do but accept a moderate shot.
It at least makes the chance of catching the flu somewhat smaller.
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