omicron, background, biology, blue, cell, change, concept, contagion, contagious, coronavirus, covid 19, covid-19, covid19, crisis, danger, dangerous, delta, delta variant, disease, epidemic, flu, health, health care, illustration, immunization, infection, medical, medicine, microbiology, mutated, mutation, new strain, outbreak, pandemic, pathogen, prevention, problem, protection, quarantine, risk, sars, science, strain, symbol, vaccination, vaccine, variant, viral, virus