inclusion criteria: * for all participants: ability and willingness of participant (or legally authorized representative) to provide informed consent prior to initiation of any study procedures. * for participants who are in, or who have completed, the activ-2/a5401 trial: receipt of all selected investigational therapy or active comparator/placebo for that therapy at selected sites. * for participants who are in, or who have completed, the activ-2/a5401 trial and receive study-provided moderna mrna-1273 covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥30 days and ≤240 days prior to study entry. * for participants who are in, or who have completed, the activ-2/a5401 trial and have received or will be receiving community-provided mrna-based covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥30 and ≤240 days prior to receipt or planned receipt of the first dose of community-provided vaccine.

inclusion criteria: * for all participants: ability and willingness of participant (or legally authorized representative) to provide informed consent prior to initiation of any study procedures. * for participants who are in, or who have completed, the activ-2/a5401 trial: receipt of all selected investigational therapy or active comparator/placebo for that therapy at selected sites. * for participants who are in, or who have completed, the activ-2/a5401 trial and receive study-provided moderna mrna-1273 covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥30 days and ≤240 days prior to study entry. * for participants who are in, or who have completed, the activ-2/a5401 trial and have received or will be receiving community-provided mrna-based covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥30 and ≤240 days prior to receipt or planned receipt of the first dose of community-provided vaccine.

inclusion criteria: for all participants: ability and willingness of participant (or legally authorized representative) to provide informed consent prior to initiation of any study procedures. for participants who are in, or who have completed, the activ-2/a5401 trial: receipt of all selected investigational therapy or active comparator/placebo for that therapy at selected sites. for participants who are in, or who have completed, the activ-2/a5401 trial and receive study-provided moderna mrna-1273 covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥30 days and ≤240 days prior to study entry. for participants who are in, or who have completed, the activ-2/a5401 trial and have received or will be receiving community-provided mrna-based covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥30 and ≤240 days prior to receipt or planned receipt of the first dose of community-provided vaccine.

inclusion criteria: for all participants: ability and willingness of participant (or legally authorized representative) to provide informed consent prior to initiation of any study procedures. for participants who are in, or who have completed, the activ-2/a5401 trial: receipt of all selected investigational therapy or active comparator/placebo for that therapy at selected sites. for participants who are in, or who have completed, the activ-2/a5401 trial and receive study-provided moderna mrna-1273 covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥30 days and ≤240 days prior to study entry. for participants who are in, or who have completed, the activ-2/a5401 trial and have received or will be receiving community-provided mrna-based covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥30 and ≤240 days prior to receipt or planned receipt of the first dose of community-provided vaccine.

inclusion criteria: - for all participants: ability and willingness of participant (or legally authorized representative) to provide informed consent prior to initiation of any study procedures. - for all participants: individuals ≥18 years of age - for participants who are in, or who have completed, the activ-2/a5401 trial: receipt of all selected investigational therapy or active comparator/placebo for that therapy at selected sites. - for participants who are in, or who have completed, the activ-2/a5401 trial and will be receiving study-provided moderna mrna-1273 covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥60 days and ≤240 days prior to study entry. - for participants who are in, or who have completed, the activ-2/a5401 trial and will be receiving community-provided mrna-based covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥60 and ≤240 days prior to planned receipt of the first dose of community-provided vaccine.

inclusion criteria: - for all participants: ability and willingness of participant (or legally authorized representative) to provide informed consent prior to initiation of any study procedures. - for all participants: individuals ≥18 years of age - for participants who are in, or who have completed, the activ-2/a5401 trial: receipt of all selected investigational therapy or active comparator/placebo for that therapy at selected sites. - for participants who are in, or who have completed, the activ-2/a5401 trial and will be receiving study-provided moderna mrna-1273 covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥60 days and ≤240 days prior to study entry. - for participants who are in, or who have completed, the activ-2/a5401 trial and will be receiving community-provided mrna-based covid-19 vaccine: receipt of the last dose of investigational therapy or active comparator/placebo for that therapy ≥60 and ≤240 days prior to planned receipt of the first dose of community-provided vaccine.