The goal of this observational study is to analyze binding antibody levels in adults in the United States (US) after receiving coronavirus disease 2019 (COVID-19) bivalent boosters (original and omicron BA.4/5) and updated COVID-19 vaccines (XBB.1.5).

Inclusion Criteria:

• Lives in the continental United States (US).
• Speaks, reads, and understands English.
• Is willing and able to submit vaccination card photo(s) or vaccination records.
• Is willing and able to self-collect capillary blood during the study period via an at-home whole-blood collection device.
• Is fully vaccinated against COVID-19 per protocol specified criteria.

Exclusion Criteria:

• Has been diagnosed with significant cognitive impairment or dementia.
• Is pregnant or planning to become pregnant during the study period.
• Primary mailing address is a Post Office box, Army Post Office, Fleet Post Office, or Diplomatic Post Office address.
• Currently lives in a US military base located overseas, or US territories (Puerto Rico, US Virgin Islands, Guam, Northern Mariana Island, or American Samoa).
• Is currently participating in a COVID-19 vaccine clinical trial.
• Is currently receiving chemotherapy or has received chemotherapy in the past 6 months.
• Is currently taking steroids, such as prednisone, for any condition.
• Has been diagnosed with and taking immunosuppressants for rheumatoid arthritis, lupus or multiple sclerosis.
• Has received an organ transplant.
• Is currently undergoing dialysis of any kind (for example, hemodialysis or chronic ambulatory dialysis) for kidney disease.

Participants who have received the COVID-19 vaccine(s) and booster.