Ключевые слова: background, bacteria, bacterium, black, closeup, concept, copy, danger, defense, disease, epidemic, flu, health, immune, immunity, immunodeficient, immunology, immunotherapy, infection, medical, medicine, ncov, nobody, notebook, object, pandemic, paper, prevent, prevention, protection, quarantine, safety, space, support, system, table, text, top, view, virology, virus, white, words, written,