Study shows immunity from COVID vaccine is not as long-lasting as people think

Since the pandemic COVID-19 is evolving, as is the scientific understanding of immunity generated by vaccines, based on messenger RNAlike Pfizer-BioNTek And modern. Since their early distribution, these vaccines have proven effective in reducing severe disease and preventing hospitalizations, which were important in the early stages of the global health crisis. However, recent studies show that the immunity generated by these vaccines wanes over time, which has led to Centers for Disease Control and Prevention (CDC) recommend periodic booster doses for certain vulnerable groups, especially older adults and people with weakened immune systems.

From October 2024 CDC The agency says it recommends that people 65 and older and people with weakened immune systems get a second dose of the updated seasonal vaccine six months after the first. This recommendation follows a pattern that has been repeated in recent years: in the spring of 2022, 2023 and again in 2024, they allowed additional booster doses after autumn vaccination campaigns, aiming to compensate for the decline in immunity in these high-risk groups. .

The continued need for additional doses compared to other long-acting vaccines such as tetanus raises questions about the durability of the immunity provided by tetanus vaccines. mRNA. While the frequency of booster shots may seem unusual, immunology and public health experts agree that the problem lies less with the effectiveness of the vaccines and more with the nature of the immune response generated against the virus. SARS-CoV-2. According to the immunologist Akiko Iwasaki belonging Yalethere is no indication that vaccines mRNA do not work, but according to scientists, there may be something special about this virus that prevents the body from maintaining a high level of long-term immunity. NBC News.

A recent study conducted by the team of Dr. F. Eun-Hyun Lee V Emory University and published in Natural medicineoffers an explanation for this phenomenon. The study analyzed the immune response in the bone marrow of 19 vaccinated adults, some of whom received up to five doses of the vaccine. mRNA against him COVID-19. The study found that while long-lived plasma cells responsible for long-lasting immunity were readily detected in people vaccinated against tetanus and influenza, these cells were absent from bone marrow samples from people vaccinated against tetanus. SARS-CoV-2according to the report US National Institutes of Health.

long-lived plasma cellswhich are generated in the bone marrow are critical to providing a sustained immune response over time as they are able to continuously produce antibodies. In the case of vaccines mRNA

against him COVID-19study suggests that cells generating antibodies against SARS-CoV-2 they may not reach full maturation in the bone marrow, which may explain why immunity wanes relatively quickly. Even in participants who had both infection and vaccination, known as “hybrid-immune” individuals, no significant levels of these long-lived cells were found in bone marrow samples.

Another factor that determines the need for regular reinforcement is high speed. SARS-CoV-2 mutation. Unlike other viruses, such as measles, which have shown stability over time, SARS-CoV-2 It continues to adapt and mutate, making it difficult to maintain stable and long-lasting immunity with a single vaccine. Doctor Anna Durbininfectious disease doctor in Johns Hopkins Universityindicates that the situation is similar to that of influenza, where the virus changes from season to season, forcing the vaccine to be updated annually to reflect the prevailing strains. However, COVID-19 poses a greater challenge due to its mutation rate, which exceeds that of influenza.

For his part, Dr. Ashish JhaDean of the School of Public Health Brown University and former response coordinator COVID-19 V White Housestresses that the problem is the changing nature of the virus, not the limitations of the vaccine. According to JahAccording to information from NBC News.

Scientists continue to research how to improve long-term immune response to SARS-CoV-2. One possibility would be to develop vaccines that induce the formation of long-lived plasma cells in the bone marrow, as other vaccines induce long-lasting immunity. According to the doctor Lee

The “ultimate goal” of vaccine development will be to create one that will generate these long-lived cells against SARS-CoV-2which will reduce the need for frequent booster doses.

In addition, immunologist E. John Wherrybelonging University of Pennsylvaniasuggests that boosting immunity every six to 12 months may be an effective strategy for certain at-risk groups, such as older adults, while more effective long-term solutions are developed. The vaccine helps boost levels of antibodies, which are the first line of defense against the virus, helping the immune system respond more quickly to neutralize the infection before it causes serious illness.

Currently, six-monthly booster doses are only recommended for older adults and people with weakened immune systems, and this frequency is not expected to become the norm for all ages. According to JahUnless the virus becomes more virulent, two doses per year is unlikely to be recommended for young healthy people.