Need a COVID-19 booster shot?Answer 6 questions about how to maintain protection

Increased prevalence of New coronavirus mutant People who already have COVID-19 shots are questioning how well they are protected from the evolving form of SARS-CoV-2 virus. Here, Microbiology and infectious disease expert William Petri The University of Virginia answers some common questions about COVID-19 booster shots.

1. What is a booster shot?

Boosters are additional doses of vaccine given to maintain vaccine-induced protection against disease.They are commonly used to fortify many vaccines because they can immunize Wears over time.. For example Influenza vaccine You need a booster every year, and Diphtheria and tetanus vaccine Every 10 years.

Boosters are often the same as the original vaccine. However, in some cases, booster shots have been modified to increase protection against new viral variants.The· Seasonal influenza vaccineIn particular, the influenza virus changes rapidly and requires a booster every year.

2. Need to get a COVID-19 booster?

not yet. As of early July 2021, none of the US government authorities have recommended boosters. This includes the US Centers for Disease Control and Prevention, the Food and Drug Administration, and an advisory board on the implementation of immunization to the CDC.

3. Why are booster shots not yet recommended?

Vaccine immunity does not last forever, but it is not clear when boosters will be needed.

Encouragingly, all currently licensed COVID-19 vaccines induce strong immunological memory against the coronavirus.Vaccines teach your immune system Memory B cells It produces antibodies when exposed to the virus. Researchers have detected high levels of memory B cells in the lymph nodes of people who have been vaccinated with Pfizer. At least 12 weeks After they were shot.

The study also found that the approved COVID-19 vaccine Emerging strains of coronavirus..According to one study, the Johnson & Johnson vaccine 73% to 82% effect By driving away severe illness from beta mutants.And a preliminary study that has not been peer-reviewed is the Pfizer vaccine. 88% valid For delta variants.

Other causes of long-term antibody response to coronavirus are Plasma blast It is present in the bone marrow. These cells continuously produce antibodies and do not require booster immunity to maintain their activity.Fortunately, plasmablasts have been detected in the bone marrow People who received the COVID-19 vaccine Shows some long-term immunological memory for up to 11 months.

4. How do I know if I need a booster?

You may have to wait for the outbreak of the vaccinated person. Researchers are still thinking of the best way to measure the strength of someone’s vaccine-induced immunity. The COVID-19 vaccine is so effective that it is unlikely that the test will fail.

The best candidates to measure are the specific antibodies that the vaccine makes to the immune system.They recognize Spike protein This allows the coronavirus to invade and infect cells.Evidence supporting the importance of anti-spiking antibodies includes studies showing the production of slightly more effective mRNA vaccines such as Pfizer and Moderna. High blood antibody levels Than adenoviral vector vaccines like Johnson & Johnson and AstraZeneca.so Preliminary research Although not yet peer-reviewed, anti-spiking antibody levels were low in people who caught COVID-19 after vaccination with the Oxford-AstraZeneca vaccine.

Healthcare professionals want to be able to provide patients with blood tests that show how well or unprotected they are against COVID-19. This clearly shows if a booster shot is needed.

But until researchers know for sure how to measure vaccine-induced immunity, the next sign that boosters may be needed is breakthrough infections in older people who are already vaccinated. Made by people over 80 years old Low level antibody After vaccination, their immunity can weaken faster than the general population.Elderly people probably Most susceptible to new viral variants Avoid the protection provided by current vaccines.

5. I have an immunodeficiency – do I have to worry?

People with immunodeficiency may need boosters.In one study, 39 of 40 kidney transplant recipients and one-third of dialysis patients Could not make antibodies after vaccination..Another study identified 20 patients Rheumatoid or musculoskeletal disorders It was a drug that suppresses the immune system, and there were no detectable antibodies. Both of these studies were conducted after the patient was given the full dose of the vaccine.

Boosters have been shown to be useful in these cases. In one study Patients with solid organ transplantation Those who responded suboptimally to two doses of the Pfizer or modelna vaccine were able to develop an antibody response on the third dose.

People with immunodeficiency may wonder if the vaccine they receive is producing immunity normally in the body. In a preliminary study that has not yet been peer reviewed, Tests specifically targeting anti-spiking antibodies Vaccine triggers can help determine if a vaccine has worked. But for now, FDA does not recommend An antibody test to evaluate immunity.

6. Does the booster need to match the first shot?

Probably not. Recent studies have shown that mRNA vaccines such as Pfizer and Moderna can be mixed with adenovirus-based vaccines such as AstraZeneca. Equivalent result..

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