coronavirus variant

covid eg5 subvariant variant dominant strain mutating virus subvariants omicron coronavirus b117 coronaviruses mutation eris covid19 concept conceptual sars flu outbreak influenza pandemic diagnosis coronavirinae microbe infect epidemic lethal pathology pathogen virology sickness health retrovirus superbug immunity human pathogenic medical spike protein science biology antibiotics bird avian microbiology symptoms render bacterial infection illness contagious vaccine treatment covid-19 5 viral disease cell background