coronavirus word and question mark made in dirt, dust, ash and filth as unknown, uncertain

answer antibiotic ash bacteria concept contagious coronavirus covid19 danger death dirt dirty disease dust dusty enemy epidemic fever filth germ global health healthcare humanity hygiene illness infect infection kill killer lethal made mankind mark medical medicine microbe microorganism mystery pandemic panic pathogen prevention question questionable risk sars sarscov2 sickness spread symptom system uncertain unknown vaccine virus war word