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