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Superior immunity

Chris Helgren / Reuters / Fotoarena

Studies of blood and tissue samples taken before the COVID-19 pandemic may help explain why the disease is more common and more severe in adults than in children. A team led by Scott Boyd, from the Stanford University School of Medicine, USA, analyzed 12 samples of umbilical cord tissue and blood from 93 children aged 1 to 3, as well as blood samples from 114 adults of various ages and eight blood and tissue samples from eight deceased adults (Science, April 12). The researchers tested the capacity of B lymphocyte immune cells to recognize a number of pathogens. They found a much higher frequency of B lymphocytes capable of reacting to the SARS-CoV-2 virus in the samples from children. The hypothesis is that more recent exposure to other coronaviruses among children allows their immune systems to better identify SARS-Cov-2, while adult B lymphocytes have already lost the ability to deal with this type of infection.