Why flu is particularly dangerous for the elderly

Why flu is particularly dangerous for the elderly

An influenza virus is the most dangerous for over 60s. Researchers have now developed special vaccines for the elderly. Their effectiveness is not proven yet, but the first products are already available.

rib is particularly dangerous for older people because their immune system has lost its effectiveness over the years. Which protection mechanisms are affected in detail, scientists have now examined in a study.

The immune system of older people reacts slower and less variable on the flu shot than younger people. As they age, the B cells that are crucial to the immune response and the antibodies they produce no longer accumulate as many mutations that ultimately allow the immune system to respond to a large number of different types of pathogens.

Specifically, this means that the immune system can no longer respond to new virus variants as effectively as it is at a younger age, now report US scientists in the journal “Cell Host & Microbe” .

“The key conclusion is that when newly circulating influenza viruses infect the elderly, they may not have the right tools to fight because their antibodies are not as protective,” explains study leader Patrick Wilson of the University of Chicago . “Our findings could be used by the vaccine community to make better vaccines and improve the protection of the elderly population.”

Influenza viruses are constantly changing their shape, more specifically, tiny features are changing on their surface. Exactly these characteristics recognize the immune system. It forms antibodies that attack these structures – thereby destroying the viruses. The vaccine is adjusted annually as well as possible to the currently circulating virus types with their characteristic surface features.

The immune system responds to the constant changes of the viruses, among other things with a process called “somatic hypermutation”. The antibody genes of a B cell mutate, so that ultimately different antibody variants can be formed. The cells that are best able to recognize and fight a virus are selected – they form the appropriate antibodies as needed.

Older people react weaker to new virus variants

Among other things, the scientists investigated how this process changes with age. They compared how B cells from younger (22 to 64 years) and older adults (71 to 89 years) react when vaccinated with different influenza viruses.

It has been shown that younger people’s B cells are constantly accumulating mutations. In older age, this ability diminished and subjects had a somewhat variable repertoire of B cells. Their antibodies were increasingly directed against very conservative features of the viruses. They responded therefore mainly to historical virus variants that circulated in the childhood of the subjects, the immune response to newer virus variants was much weaker.

A vaccination remains the best protection against influenza, the scientists emphasize. “We do not say that people should not get vaccinated, or that the current vaccines are useless to the elderly,” says researcher Carole Henry, who also works at the University of Chicago. The aim is rather to further improve the vaccines.

First variants especially for the elderly are already available. Such vaccines include special enhancers. However, there are still scientific studies in which the specific immune response to these vaccines must be investigated and proven.

The declining effectiveness of the immune system in old age is considered to be a central cause of illness and death, as the resistance to bacteria, fungi and viruses wears off. The number of deaths from flu illnesses varies considerably from year to year, with the disease being the most dangerous for over 60s.

The Standing Vaccination Commission at the Robert Koch Institute in Berlin (Stiko) therefore recommends influenza vaccination especially for those aged 60 or over. Even if the immune response is weaker for them, older people with a vaccine could already halve their disease risk today. In addition, the disease is mild in vaccinated people.