coronavirus outbreak and coronavirus influenza history as dangerous cases of influenza strain as pandemic medical risk concept wit

abstract antibiotics asian background bacterial biology bird blood carnivore carnivores carnivorous cell concept coniferous contageous contagious corona coronaries coronary coronavirinae coronavirus coronaviruse coronaviruses covid crossfire crossfires diagnosis disease epidemic fever flu granaries health human illness illustration immunity infect infection influenza macro medical microbiology microscopic new pandemic pathogen pathogenic pathology rhinovirus sars science strain superbug symptoms treatment vaccine virology virus viruses