Experts say COVID-19 booster shots aren’t needed yet

Increasing evidence suggests that Shot provides long-term immunity, even against new varieties.

In addition to antibodies that act fast and attack coronavirus peaplomers, our body has a cell-mediated immune response, including T cells and memory B cells.

“Vaccines induce much more than antibodies. T-cell immunity is an important component of immunity and is often ignored by the media when reporting on vaccination studies.” Dr. Ameshua DarhaAn infectious disease expert and senior scholar at the Johns Hopkins University Center for Health and Security, he told Healthline.

Both T cells and memory B cells are hidden in the lymph nodes and take action as soon as a pathogen is detected in the future.

T cells are essential for long-term immunity and protection against serious illness.

According to, all major vaccine clinical trials examined T cell production and concluded that Shot produced a strong and durable T cell response. Dr. Monica Gandhi, An infectious disease specialist at the University of California, San Francisco.

Multiple studies These T cells, which target several parts of SARS-CoV-2, have been shown to withstand over time.

Memory B cells are also generated and are expected to “begin action upon re-exposure and produce antibodies long after vaccination,” Adalja said.

Memory B cells are a type of B cell produced by the immune system in response to exposure to antigens. They persist in the body (in lymphoid tissue, organs, bone marrow, and circulation) for months to years, depending on the specific antigens they produce in response.

A paper When an immune person is exposed to a new mutant, B cells can produce new antibodies that specifically target the mutant, announced last month.

Memory B cells “do not produce antibodies to some older ancestral strains, they will produce antibodies to what they see,” Gandhi said.

the study Researchers have detected B cells in people’s blood at least eight months after infection, indicating that B cells appear to last longer.

Scientists have not yet discovered how long the protection from T cells and memory B cells lasts, but studies of other viruses have shown that it can last for years in some cases.

For example, in the case of measles, T cells 34 years After vaccination.

Currently, those who have been vaccinated with a single dose of Johnson End Johnson are unlikely to need booster shots of messenger RNA (mRNA) vaccines such as Pfizer-BioNTech or Moderna.

According to Gandhi, there is currently no evidence that people who receive a J & J shot have more breakthrough infections than those who receive one of the mRNA vaccines.

J & J Shot works like an mRNA vaccine. It uses DNA to produce mRNA and looks exactly like an mRNA vaccine. It doesn’t make much difference, “Gandhi said.

According to Gandhi, antibodies are constantly declining after vaccination, and if scientists only measure antibodies when assessing immune persistence, booster shots will always be recommended.

Antibody levels are not our only clue as to how immunity persists. T cells and memory B cells will also step up into the battle.

Recent data Shows that J & J shots generate potent antibody, T cell, and B cell responses to variants. Including Delta..

According to Adalja, immunocompromised people who do not show a strong immune response after vaccination may benefit from booster shots.

“I don’t think the general population will need short-term boosters, although immunosuppressed populations may need boosters at shorter time intervals,” Adalja said.

Scientists need to continue to study how the immune response of vaccinated people, including both the general population and immunocompromised people, behaves over time.

If more and more vaccinated people begin to experience severe breakthrough infections, different doses may be needed to boost antibodies to new mutants.

“For me, the booster vaccine threshold is when a fully vaccinated individual is hospitalized for a breakthrough infection, which only happens in rare cases,” Adalja said. It was.

As new variants emerge and spread, there is growing speculation as to whether booster shots will eventually be needed to maintain protection against COVID-19.

However, many infectious disease experts say that vaccine-induced immunity against severe COVID-19 appears to be strong and long-lasting, suggesting that booster shots are probably not needed immediately.

Scientists continue to observe people over time to understand how long protection against severe illness lasts.