This is a pilot, cross-sectional, sample collection study to characterize the immune response and intestinal microorganisms in people with and without COVID-19 antibodies and helminth infection.

This is a pilot, cross-sectional, sample collection study to characterize the immune response and intestinal microbiota in people with and without SARS-CoV-1 antibodies and helminth infection.

A target sample size of 1500 participants aged 5 years or older will undergo a one-time blood and stool collection for SARS-CoV-2 antibody testing, diagnosis of parasitic infections, and experimental studies including transcriptomics (RNA) and microbiome (intestinal microorganisms) characterization. Participants willing to take part in the study will be selected from households in the Tiruvallur district, Tamil Nadu, India. Individual study participation involves a single study visit. Participants will be informed of the results of clinical testing and will be referred for medical care as appropriate.

Inclusion Criteria:

• Able to provide informed consent.

Exclusion Criteria:

• Poor venous access precluding venipuncture.
• History of any illness or condition which, in the investigator's judgment, may substantially increase the risk associated with the participant's participation in the protocol, or compromise the scientific objectives.

Participants may be co-enrolled in other studies; however study staff should be notified of co-enrollment.

Eligible participants will be enrolled from households in the Tiruvallur district, Tamil Nadu, India. Villages and towns in the Tiruvallur district will be selected in consultation with the Department of Public Health, Tamil Nadu. Areas that are known hotspots for COVID-19 will be selected.