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Flu vaccine: why the protective effect of a flu vaccine decreases once a year

Nobody wanted to believe the first remarks before nearly forty years. In 1979, British physician Trevor Hoskins reported strange observations. He was vaccinated against 800 flu-like teenagers at an intern near London. After that, he found that injection did not work equally well for all the boys. Flu protection was only half for some as well as for others.

Hoskins paradox

Students who did not receive the vaccine were those who were vaccinated last year. In fact, one could expect the opposite. The observation was called Hoskins paradox and entered the books of medical history. But that was it. Soon the discovery was forgotten. At least since last year, Hoskins is now talking about himself again. His paradox has become one of the hottest topics in influenza research.

For example, events of last season match the effect: In the summer of 2017, the Australia flu epidemic was particularly severe. In the winter, viruses moved to the northern hemisphere. Here and there their attacks were confusing. As expected, the worst ones were for uninhabited people. However, the second most prominent were the persons who had been vaccinated the previous year – as in the Hoskins custody school. The refreshment was successful only in one of the ten cases. For the new vaccinated, the syringe worked four times.

This problem only occurred with one pathogen, the H3N2 virus. But this is especially afraid: Compared to those who currently circulate H1N1 and Influenza B viruses, it is much more dangerous for the elderly. In addition, this is the fastest way to change the structures that doctors target with vaccines. Manufacturers try to customize their products every year. But they always fail. So last winter.

No other vaccine is so common

Earlier, says Danuta Skowronski, such phenomena are often ignored in order to avoid discussion of their effectiveness. Meanwhile, influential researchers from the Canadian Ministry of Health in the British Columbia state are being considered closer. Thanks to the new technologies, she and her team have discovered that the Paradox of Hoskins is a rule, not an exception. Even in 2014, people who just wanted to refresh their vaccine were much worse protected. In the season four years earlier, it seems that the syringe in the studio does not do anything. In some winters, the effect is barely noticeable. Why does it so remain a mystery. It is also unclear whether vaccination over a number of consecutive years has further increased the weakening.

It will be important to know. Because a flu vaccine often does not give another vaccine. Against measles, mumps and rubles coming to retirement, only two syringes together, against the flu, can be 65. "And no one can say exactly what this has for long-term effects," says Danuta Skowronski.

For the epidemiologist, it is clear: "We need to clarify the effects and causes of these effects." After all, every sixty and sixth German specially threatening annual flu vaccine is officially recommended in the United States even to all people.

Re-learning for other flu viruses is prevented

The most likely explanation is as follows: If antibodies develop after one year of vaccination, they can neutralize the new vaccine. This is especially true if the vaccine remains unchanged. Therefore, there would not be a fresh anti-mob shooter with which defensive cells attacked the new generation of viruses. Other effects of so-called negative interference could not be detected in the vaccination of several hundred million people.

Perhaps another factor is the suspect, Ana Rita Gonçalves Cabecinhas of the Swiss National Center for Influenza at the University of Geneva. In their opinion, childhood experiences are also crucial to the effects of the vaccine.

According to the theory of antigenic prints, presented by many colleagues in the field, the influenza virus puts the imprint on the immune system of the child at first contact. The immune system is directed to fight in life, especially this flu virus. Re-learning seems to be possible only to a limited extent.

Reduce the danger

"This would help explain, for example, why H3N2 is particularly dangerous for older people," says the virologist. This subtype began to infect people in 1968. Today's seniors have never met him in the youth. The cause of her childhood was H1N1. When 2009 began in the key word of swine flu in the pandemic, the elderly showed a surprising immune – at least compared to the younger one. Anyone who was a child between 1957 and 1977 did not have the opportunity to prepare for it. During that time, the H1N1 viruses were sunk so they spoke. For people who usually go to the vaccine, the effect of the seal could even increase, some experts say. That is why the memory refreshes every year.

That is why some scientists now recommend vaccination every other year. Experts like Edward Belongia from the Marshfield Clinic Research Institute in Wisconsin believe this advice is premature. "With vaccine, it's getting healthier," says researchers of influence. The same applies to common vaccinations.
Even if negative interference causes some vaccines to catch the flu, they are even better than without syringes, he explains. The danger of serious illness, which scientists could show several times, also falls by more than 50 percent, even when it comes to protecting the vaccine.

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