Corona virus: Why is it difficult to vaccinate elderly people with...

• William Park
• BBC

If we imagine that we live in an alternate virtual world and already have a vaccine to prevent the Coronavirus, then world leaders will have to choose how it benefits the population. Protection will likely be provided to the most vulnerable people first, along with nurses, doctors and care workers.

But if it were that simple, the most vulnerable age group, the elderly, would be particularly difficult to vaccinate.

“We have very few vaccines for the elderly,” says Shayan Sharif, professor of vaccinations at the Canadian University of Guelph. “The last century has seen most vaccines innovate to provide protection from childhood diseases.”

“Neurogenic herpes” is the only exception, and it is usually given to patients at the age of 70, and there are one or two other vaccines for diseases such as meningitis or HPV that have been developed for young adults, but otherwise the immunology tilts in favor of children.

“We have an enormous amount of knowledge about childhood diseases, but when it comes to young people, in middle age and old age, we don’t have much experience,” says Sherif.

To understand why elderly people can be difficult to vaccinate, we need to look at the differences in their immune systems.

The elderly suffer severely from infectious diseases compared to younger adults. The elderly have more risk factors. Their lifetime exposure to carcinogens or other infectious diseases increases the risk of developing diseases in the future, but it is also subject to something known as “the aging of the immune system.”

Our immune system, just like many other parts of the body, experiences signs of aging, and some immune cells lose their function. The immune system is a very complex network of cell types that interact with each other. And if something somewhere inside the machine is not working, it messes up the delicate balance of the immune response.

How does the immune system work I have a person The elderly?

When you are infected with a pathogen, the first layer of the immune system, the innate immune response, begins to attack the pathogen at the site of infection, and for respiratory diseases, that site can be the lungs, trachea, or nose, attacking white blood cells, or Macrophages are the pathogen, and they swallow it up before destroying it.

As macrophages break down the pathogen inside, they refer bits and pieces of it to another type of immune cell known as T cells.

These cells are the “memory” of the immune system. They cannot see the pathogen on their own and need specific macrophage cells called antigen presenting cells to identify the pathogen, and this process activates the next layer, the adaptive immune system.

There are several types of “T” cells, such as killer “T” cells, or cytotoxic, that attack the cells of our bodies in order to eliminate those cells that are already infected by the pathogen and limit its spread. The helper T cells provide support for B cells, another part of the adaptive immune system.

The B cells can see the pathogen on their own, but in order to function optimally they need the helper T cells, and the B cells produce antibodies, but to produce the most effective antibodies, they need this. Complex interaction with T cells.

The goal of the vaccination is to stimulate our immune systems to produce effective antibodies before we are exposed to the pathogen.

And many news have talked about antibody tests as a way to verify that people are infected with the Coronavirus, and despite this, not all antibodies are effective, and not everyone who has been infected with SARS-Cove-2, the virus that causes Covid-19, has antibodies, some bodies Countermeasures have a limited life.

The issue for vaccinologists is that the delicate balance between all these cells in the elderly becomes disrupted, so what happens then in the immune system of the elderly person?

“All these cell types are already weak in their function,” says Birgit Weinberger of the University of Innsbruck, who studies immunity and vaccines for the elderly. To be mindful is that no single cell type works on its own. “

If phagocytes weaken in presenting an antigen in old age, this may lead to decreased T-cell activation, less help with B cells and less antibody response. But this may be due to congenital problems.

“You have to consider how all of these different parts of the immune system work in unison,” Weinberger says.

Our adaptive immune system has a limited number of B and T cells, and we lose some of them over time, and that can create problems later in life, Sharif says.

“When we encounter new pathogens, our ability to respond becomes much more limited,” he adds.

Immune sensitivity does not affect all people equally, as is the case with other parts of the body, some people are aging at a slower pace than others, either by taking care of themselves or being fortunate enough to have a healthy genetic makeup, but not all of the above is Bad news. Some parts of our immune system improve with age as well.

“There are some cells in our immune system that become more active as we age. If we have been exposed to a wide range of pathogens, we have an immune memory against them, so we don’t need an arsenal of cells to respond to new antigens,” Sherif says.

However, SARS-CoV-2 is one virus we have never been exposed to, so we don’t have that memory.

This is the balance our immune system achieves: Older adults have a better immune memory of things they have already been exposed to, but they have a more limited repertoire of responding to new diseases.

There’s no problem with that, but as humans come into contact with more pathogens that adapt to live and grow in the other species they transmit to (so-called zoonotic diseases) often, our ability to deal with a new disease may be more important.

When vaccines undergo human clinical trials, they are tested in the first phase to ensure safety (usually on a small number of individuals), then enter the second phase to test their effectiveness (whether it will produce the response that you intended) and the third phase to see their effect (if they really do produce) Correct response, and does it actually protect against disease).

Vaccines are a compromise. While it may work well on one group of people, it may work less well on others, and there are currently many clinical trials of Covid-19 vaccines, many of which may reach through development to approval and approval.

And that is how good things are for Weinberger and Sheriff. Having a range of vaccines that you can rely on means we can choose from among them one that fits the right scenario, and one that might work for the elderly better.

There will never be a perfect and flawless vaccine. “No single vaccine can provide a 10 percent efficacy,” says Sharif.

Although all approved vaccinations will need to be emphasized that they protect against diseases, not all vaccines will prevent disease transmission.

Most vaccines work by preventing the pathogen from its function, but they do not necessarily terminate its presence in the body, which means that the person who received the vaccine may still produce viral particles, and thus potentially infect others around him.

This has an important effect on how we choose to vaccinate a population, for those who have to decide who gets vaccinated, their focus should be on the vulnerable, but if we vaccinate nurses, doctors, and care workers without vaccinating their patients first, then Although these key workers may have protection, they can pass the pathogen to other vulnerable people.

Sharif says: “A vaccine can disrupt transmission, but it is unlikely that we will find a vaccine that completely stops transmission of the virus. Influenza vaccines are in fact a good example: they do not do much to reduce transmission, but they alleviate disease.”

Weinberger says that the vaccination strategy is like a complex puzzle of social, medical, political and economic factors, but what should be clear is that while the death rate is much higher in some groups, it must be prioritized, and others need to get used to living with the virus. .

How age affects the spread of the virus remains largely a mystery, and Weinberger raises concerns about some early research indicating that children were less contagious.

She says that these studies were not optimal to reach this conclusion, because they were conducted when children in Europe were out of school hours, so can these children now catch the virus in school and spread it to grandparents when they come to pick them up from school at the end of school?

A better understanding of the spread of the virus will contribute to knowing the best strategies for vaccinating the population, and Weinberger says: “We are doing a very good job of accelerating the process (developing a vaccine), but in order to make some decisions we need to know first.”

Since we first started treating people for “Covid-19”, medical knowledge about treatment drugs has made great progress even if it received only rare coverage in the news, something Sharif finds puzzling.

He says that few people may know about the progress in immunotherapy because they are outside the scope of the spotlight, and we can all take a picture of the vaccine, and we must be able to remember that we have the vaccine, but if you are asked to draw a picture of an immunotherapy, can you call a picture ?

“Sometimes we put blindfolds on our eyes and say that vaccinations are the only savior, but this is not the case, and vaccines can take between 14 and 28 days and require multiple injections. Immunotherapy can work in minutes and hours,” Sharif says.

He adds: “The most urgent hope for elderly people who suffer with Covid-19 may be the development of a drug that reduces the time of stay in the hospital from weeks to days, or even a drug that negates the patient’s need to enter the intensive care unit at all.”

Research is currently underway on hundreds of drugs as potential treatments for Covid-19, one of the most promising is “dexamethasone”, a steroid that has been shown to reduce the mortality rate of patients receiving oxygen, which has been approved for use in the United Kingdom and Japan, and was given to President Trump when he was transferred. To hospital due to contracting the disease earlier last month.

There are currently five drugs licensed for “emergency use”, including “dexamethasone”, in the United States by the FDA.

None of these five drugs has so far received approval from the authority after being clinically tested, and therefore all of them are only used in very specific cases, but the benefit of searching for a treatment among the known drugs is that they have already obtained approval and have proven to be safe in other contexts.

Therefore, their adoption after a successful clinical trial should be relatively fast, much faster than the amount of approval required for a new vaccine.

Older people treated in hospital may benefit from this curative research before seeing a vaccine. So, while vaccinations may be a little distant, there are other reasons for us to be positive.