WASHINGTON : Scientists have found a key factor which may explain why the novel coronavirus predominantly affects adults and older people while seeming to spare younger children, an advance that may lead to the development of new treatment strategies for COVID-19.According to the researchers, including those from the Vanderbilt University Medical Center (VUMC) in the US, children have lower levels of a receptor protein that the coronavirus SARS-CoV-2 needs to invade airway epithelial cells in the lung.The findings, published in the Journal of Clinical Investigation, support efforts to block this protein to potentially treat or prevent COVID-19 in older people, the scientists said."Our study provides a biologic rationale for why particularly.