ba.4. new variant of the sars-cov-2 coronavirus. subvariant of omicron. horizontal. virus and black text.

2019 alert ba4 background biology black blood cell concept corona coronavirus cov covid danger death design disease epidemic fever flu global health horizontal human illness illustration infection infectious influenza isolated macro medical medicine microbe microbiology microscopic ncov new omicron outbreak pandemic pathogen pneumonia risk sars sarscov2 science scientific sickness subvariant syndrome system text vaccine variant vector viral virology virus warning