Data Collection
A questionnaire was distributed to each participating staff who had verbally consented. This questionnaire was self-completed to gather information on basic demographics, including gender, age, and current residential address showing the district they are living in. Name of the staff and their contact numbers were recorded for contact tracing purposes if more assessments are needed after the serology test. Other details obtained include epidemiological factors for infection (possible contact with COVID positive patients, COVID clusters, or traveling to foreign countries) and clinical factors (fever, cough, sore throat, runny nose, or other specified symptoms). Participants were asked to write down the exact date of symptom onset and last travel or close contact date if present. The list of COVID clusters mentioned in the questionnaire was based on the daily statement released by our State Disaster Committee at the end of March 2020.27