* acute severe illness * recent receipt of a blood product * history of thrombocytopenia * pregnant females * any chronic medical condition * any participant receiving any immune suppressive medication * immunocompromised staff * participants who have egg allergy * participants who care for immune compromised hosts * participants who test positive for covid-19 serology prior to randomization

* acute severe illness * recent receipt of a blood product * history of thrombocytopenia * pregnant females * any chronic medical condition * any participant receiving any immune suppressive medication * immunocompromised staff * participants who have egg allergy * participants who care for immune compromised hosts * participants who test positive for covid-19 serology prior to randomization

- acute severe illness - recent receipt of a blood product - history of thrombocytopenia - pregnant females - any chronic medical condition - any participant receiving any immune suppressive medication - immunocompromised staff - participants who have egg allergy - participants who care for immune compromised hosts - participants who test positive for covid-19 serology prior to randomization

- acute severe illness - recent receipt of a blood product - history of thrombocytopenia - pregnant females - any chronic medical condition - any participant receiving any immune suppressive medication - immunocompromised staff - participants who have egg allergy - participants who care for immune compromised hosts - participants who test positive for covid-19 serology prior to randomization