What is “immune imprinting”? Is it making bivalent boosters less functional?

Countries such as the United Kingdom and the United States have presented bivalent reinforcements since last September. They were expected to protect better against coronavirus infection, compared to the original vaccine.

All seemed happy here until some studies came out showing that immune imprinting may be making bivalent boosters less effective than everyone expected.

In early January, the New England Journal of Medicine (NEJM) published two articles saying that bivalent boosters that were supposed to defeat Covid-19 strains and Omicron strains failed to generate a greater number of antibody responses compared with the original mRNA. vaccines.

Immune imprinting is considered the main reason behind this.

What is immune imprinting?

Immune imprinting is nothing more than the body’s tendency to repeat the immune response based on the first variant it came into contact with, whether through infection or vaccination, in case it encounters a new or somewhat new variant. different from the same pathogen.

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It was in 1947 when the concept of immune imprinting first came to light. The scientists observed that the bodies of people who had previously been infected with flu and were vaccinated against the current circulating strain produced antibodies against the first strain they had come into contact with. This had been discovered in a report presented in the magazine. Nature.

In those days it was called “original antigenic sin”. Today, however, the concept is called imprinting.

In the years to come, scientists have come to the conclusion that this print plays the role of a database for the body’s immune system. This database helps the body have a better response to repeated infections.

Once the body has come into contact with a virus for the first time, the body generates memory B cells. These cells circulate in the bloodstream. These then rapidly produce antibodies just when the body is exposed to the same strain of virus again.

Isn’t that a good mechanism of the body?

It is a beneficial mechanism, but not always. The problem arises when a variant of the virus that is simply similar, but not actually identical, comes into contact with the body. In these cases, the body’s immune system activates memory B cells, rather than producing new B cells. Now, when these memory B cells are produced, they produce antibodies that bind to the characteristics seen in both strains, the old and the new one. This is known as cross-reactive antibodies.

Now, cross-reactive antibodies are not completely wasteful; They do provide protection against the new strain. However, they are not as effective in protecting the body compared to those produced by B cells in the case when the original virus first encountered the body.

What do recent studies have to say?

Researchers at Columbia University Vagelos College of Physicians and Surgeons in New York conducted a study involving 40 participants. These people have already received three injections of the monovalent vaccine (the original vaccine). In the experiment, 19 of these 40 participants were offered a booster (which was actually the fourth injection) of the monovalent (original) vaccine. The other 21 participants received a booster dose of the new bivalent vaccine.

The experiment found that the bivalent boosters failed to elicit a significantly greater maximal virus-neutralizing antibody response compared to the original monovalent vaccines.

In another study, researchers at Beth Israel Deaconess Medical Center in Boston looked at immune responses in 15 people. These participants had received the original monovalent reinforcers, while 18 other participants had their response to the bivalent reinforcers recorded.

As a result, the median BA.5 (Omicron) neutralizing antibody titer was found to be similar to post-monovalent and bivalent mRNA boosting, along with a modest trend leaning toward bivalent boosting by a factor of 1.3.

These two studies and more point to the fact that immune imprinting could be creating a barrier to the effectiveness of bivalent vaccines.

In 2022, Professor Rosemary Boyton, together with her team, conducted a study at Imperial College London on the same topic. The professor and team found that Omicron infection had little or no advantageous effect in stimulating either part of the immune system. The study consisted of more than 700 participants. The immune systems of these 700 participants had been imprinted with older variants of the coronavirus.

David Ho, authors of the research from Columbia University, made a statement in an interview saying that they were waiting for the results they found. In vaccinology, there is a phenomenon called immunological imprinting: the phenomenon means that “the immune memory preferentially sees what it has seen before.”

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If bivalent reinforcers are not as effective as monovalent reinforcers, is it okay to omit them?

No. David Ho clarified the doubt by saying that even if the boosters are not as good as the original ones, people should receive their bivalent boosters.

What did the World Health Organization (WHO) say?

The World Health Organization (WHO) warned last year, saying: “Most benefits come from giving a booster vaccine, regardless of whether it is a monovalent or bivalent vaccine.”

As scientists suggest, regardless of the type, coronavirus vaccines are extremely important in keeping this serious disease at bay. However, currently, the need of the hour is to introduce a vaccine that has the ability to combat immune imprinting and at the same time combat virus transmission.

Is there a way to solve the problem of immune imprinting?

Currently, there are many studies looking for a method to bypass immune imprinting. Some scientists have suggested that nasal vaccines may be better at stopping infections compared to injected vaccines.

These scientists believe that mucous membranes would offer stronger protection, regardless of whether they contain traces of previous encounters.

Many researchers around the world are also trying to find out if coronavirus vaccines could be spaced out each year and if this could help avoid the problem of immune imprinting.

David Ho also expressed in an interview that a considerable amount of effort is being devoted to the development of pan-sarbecovirus vaccines. These vaccines will protect against all variants that cause COVID. These vaccines can even protect us against SARS and other viruses. However, such a vaccine should not be expected to be developed overnight. The efforts will take time to bear fruit.

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Categories: Optical Illusion
Source: sef.edu.vn

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