For　the　past　two　years,　people　worldwide　were　experiencing　one　of　the　most　massive　pandemics,　the　COVID-19.　It　is　caused　by　a　virus　that　is　called　Severe　Acute　Respiratory　Syndrome　Coronavirus　2　(SARS-CoV-2),　which　mainly　attacks　the　respiratory　system.　Since　there　is　no　previous　experience　treating　the　disease,　the　drug　development　process　is　extremely　difficult.　People　in　dire　need　of　vaccines　were　urgently　needed　to　restore　their　lives　to　normal.　As　time　went　by,　medical　staff　and　experts　spent　numerous　amounts　of　time　and　effort　studying　this　virus.　Nowadays,　as　the　vaccine　technology　of　various　countries　was　very　mature,　vaccines　with　various　technological　paths　have　entered　the　experimental　stage　one　after　another.　Eventually,　effective　vaccines　are　finally　ready　for　wild　inoculation　for　everyone　by　collaborating　with　all　medical　researchers.　Currently,　there　are　four　kinds　of　COVID-19　vaccines　available　in　different　countries.　They　are　inactivated　vaccines,　mRNA-based　vaccines,　viral　vector　vaccines,　and　recombinant　vaccines.　Most　of　these　COVID-19　vaccines　are　in　Phase　3　and　provided　in　different　countries.　Those　vaccines　were　manufactured　in　different　countries,　and　their　general　production　and　technical　characteristics　will　be　discussed　in　the　following　paragraphs.　The　main　purpose　is　trying　to　provide　some　fundamental　and　comprehensive　background　knowledge　about　currently　available　COVID-19　vaccines.　It　could　be　a　reference　list　for　those　audiences　who　have　not　decided　to　take　which　vaccine.　©　The　Authors,　published　by　EDP　Sciences.