Two COVID-19 vaccines were approved by FDA for emergency use. They used a technology that was not previously available in FDA-approved vaccines. Both vaccines were successful in clinical trials and have been widely credited for reducing the incidence of disease. However, there are still concerns about how long the immunity that has been induced by this vaccine technology.A study by scientists at Washington University School of Medicine, St. Louis has shown that vaccines can trigger an immune response that is strong and long-lasting. Nearly four months after their first dose of the Pfizer vaccine, patients still had germinal centers in the lymph nodes that were producing immune cells against SARS-CoV-2 (the virus that causes COVID-19). Natural infection or vaccination can create germinal centers. These centers are a boot camp for immune cells. They are where inexperienced cells learn to recognize the enemy and sharpen their weapons. A better response from the germinal center may mean a better vaccine.High levels of neutralizing antibodies were also produced by vaccination against all three types of the virus, as well as the Beta variant, which is from South Africa and has been resistant to vaccines. People who were infected with SARS-CoV-2 had stronger antibody responses than those who hadn't been.Moderna and Pfizer reported in April that their vaccines offered at least six months protection. These reports were based upon tracking the incidence of COVID-19 in vaccinated persons. Other studies have also examined antibody levels and found that the vaccine offers at least six months of protection. However, no one had ever looked at how the immune system was responding to the vaccine. This could give important clues about the strength and persistence without the need for years of follow up.Senior author Ali Ellebedy, PhD is an associate professor of pathology and immunology, medicine, and molecular microbiology. "Germinal centres are the key to a sustained, protective immune response." "Germinal centres are where our immune memories form. The longer we have a germinal centre, the stronger and lasts the immunity. This is because there's fierce selection happening there and only the most resilient immune cells survive. After the first dose of vaccine, we found that germinal centres were still functioning 15 weeks later. We are still monitoring germinal centers and have found that they are not declining in some individuals. This is amazing.Scientists are still unsure why vaccines such as smallpox provide strong protection that lasts for a lifetime while others such as the vaccine against whooping cough require boosters. Many believe the difference is due to the quality of vaccines.AdvertisementModerna and Pfizer vaccines were developed using mRNA technology. MRNA-based vaccines are different from other vaccines that only provide bits of bacterial or viral proteins to stimulate an immune response. Instead, they provide instructions for the body's build-up and release of foreign proteins. Ellebedy and Jackson Turner, PhD (an instructor in pathology and immunology), teamed up to assess whether this vaccine triggers a positive germinal center response. Jane O'Halloran, MD and Jane Presti, MD, PhD were also co-first authors. The study began after the COVID-19 vaccine was made available in mid-2018 2020.Co-authors Sharlene Tefey, MD and William Middleton (MD), both radiology professors, were asked to help with ultrasound-guided sampling. Teefey, Middleton and others extracted cells from 14 patients who had received the Pfizer vaccine. Three weeks after the administration of the first dose, samples were taken. The second dose was administered just before the third dose. Samples were also taken at weeks four to seven. Ten participants provided additional samples fifteen weeks after the initial dose. The virus that causes COVID-19 has never infected any of the participants before.All 14 participants formed germinal centers three weeks after their first dose. These B cells produced antibodies that target the key SARS-CoV-2 proteins. After the booster shot, the response grew rapidly and remained high. Eighteen of the 10 patients still had germinal centers containing the virus-targeting B cells, even 15 weeks after their first dose.Presti stated, "This is evidence that there is a very robust immune response." Your immune system uses germinal centres to create antibodies that bind well and last long. Although the antibodies in your blood are the result of this process, the germinal centre is where it's happening.Researchers also collected blood samples from 41 patients who had received the Pfizer vaccine. Eight of these people were previously infected by the COVID-19 virus. The samples were taken before each dose was administered, and at weeks 4, 5, 7, 7 and 15. Antibody levels in people who had never been exposed to the virus rose slowly after the first dose, peaking one week later. Antibodies were already present in people who had been previously infected. They had higher levels than uninfected people and their levels rose quickly after the first dose.O'Halloran stated that although we didn't intend to compare vaccination effectiveness in people with or without a history, we were able to see an effect when we examined the data. You get an increase in your antibody levels if you have already been infected. Even if you have had COVID-19, the vaccine is clearly beneficial. We recommend that anyone who has had COVID-19 receive the vaccine.The National Institute of Allergy and Infectious diseases of the National Institutes of Health supported this study with grant and contract numbers U01AI141990 and R01 AI157155, AI134907 and 75N93019C00051; NIH grant number UL1TR001439; Sealy & Smith Foundation; Kleberg Foundation; John S. Dunn Foundation, the John S. Carter Foundation; Gilson Longenbaugh Foundation, Summerfield Robert Foundation, and a Helen Hay Whitney Foundation postdoctorial fellowship. The samples were obtained from the Washington University School of Medicine's COVID-19 biorepository, which is supported by the NIH/National Center for Advancing Translational Sciences grant number UL1TR002345.
