Safety and Immunogenicity of a Monovalent mRNA Vaccine Encoding Influenza Hemagglutinin in Adult Participants 18 Years of Age and Older

Presence of any unsolicited systemic adverse events (AEs) reported in the 30 minutes after injection

Number of participants with unsolicited systemic immediate adverse events (AEs)

Time frame: Within 30 minutes after injection

Presence of solicited injection site reactions (ie, pre listed in the participant's diary card [DC] and in the electronic case report form [eCRF]) occurring up to 7 days after injection

Number of participants with solicited injection site reactions

Time frame: Up to 7 days after injection

Presence of solicited systemic reactions (ie, pre-listed in the participant's DC and in the eCRF) occurring up to 7 days after injection

Number of participants with solicited systemic reactions

Time frame: Up to 7 days after injection

Presence of unsolicited AEs reported up to 28 days after injection

Number of participants with unsolicited AEs

Time frame: Up to 28 days after injection

Presence of medically attended AEs (MAAEs) reported up to 28 days after injection

Number of participants with medically attended adverse events (MAAE)s

Time frame: Up to 28 days after injection

Presence of serious adverse events (SAEs) and adverse events of special interest (AESIs) throughout the study

Number of participants with serious adverse events (SAEs)

Time frame: From baseline up to 6 months

Presence of out-of-range biological test results (including shift from baseline values) up to 28 days after injection

Number of participants with out-of-range biological test results

Time frame: Up to 28 days after injection