In other words, the decline in the neutralizing antibody response may result in limited protection against SARS-CoV-2 infection. These variants of concern can also escape neutralization by antibodies in vaccinated individuals. Moreover, vaccinated individuals tend to produce lower levels of neutralizing antibodies against variants of concerns, such as the Delta variant. The levels of neutralizing antibodies against the wild-type SARS-CoV-2 tend to wane a few months after the second dose of the vaccine. Some studies have suggested that neutralizing antibody levels tend to predict the degree of protection against SARS-CoV-2 infection. Neutralizing antibodies produced by B cells, which are a type of white blood cell, bind to the virus to disrupt its ability to infect human cells. The production of the coronavirus spike protein by cells in the human body generates an immune response involving antibodies and T cells. The Oxford-AstraZeneca and Pfizer-BioNTech vaccines deliver the genetic information that encodes for the SARS-CoV-2 spike protein to human cells, enabling them to produce this protein. The study appears in the journal The Lancet. The study found that both schedules were effective in boosting immune response at 28 days after the booster shot and produced well-tolerated side effects. Previous studies that used heterologous dosing for the initial two doses suggested that this approach may provide greater protection against a SARS-CoV-2 infection than a homologous schedule.ĭata on the inflammatory side effects and immune protection offered by different heterologous and homologous COVID-19 prime-boost vaccine schedules are necessary to make policy decisions about the choice and dose of the booster vaccine.Ī recent randomized clinical trial called COV-Boost assessed the safety of and immune response generated by heterologous and homologous booster schedules in individuals who received two initial doses of either the Oxford-AstraZeneca vaccine or the Pfizer-BioNTech vaccine. Such a mix-and-match approach to vaccination, otherwise known as heterologous dosing, may be advantageous over a homologous schedule, which involves the use of the same vaccine for the prime and the boost. Moreover, the Centers for Disease Control and Prevention (CDC) allow individuals to choose a different vaccine for their booster shot than the one they received for their initial two doses. and some European countries to expand the eligibility for booster shots to all individuals over the age of 18 years. The recent rise in COVID-19 cases has prompted public health agencies in the U.S. and Europe to authorize the use of boosters for older individuals and those at higher risk of developing COVID-19 earlier this year. The evidence of waning protection against the Delta variant of SARS-CoV-2 led health agencies in the U.S. However, COVID-19 vaccines continue to confer a reasonably high degree of protection against severe disease and death at least 6 months after vaccination. Some experts suggest that this decline in immunity against SARS-CoV-2 may have contributed to the recent rise in COVID-19 cases in the United States and Europe. Some studies suggest that the protection offered by currently authorized COVID-19 vaccines against contracting a SARS-CoV-2 infection and developing severe disease starts to wane after a few months. Visit our coronavirus hub for the most recent information on the COVID-19 pandemic.
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