This study will test and follow persons quarantined at home after testing positive for SARS-CoV-2 (COV) aged 18 years and older and their household members aged 1 year and older.

The purpose of this research study is to understand how often COVID-19 (Coronavirus Disease 2019) spreads in the household when someone who tests positive for the virus self-isolates at home.

The purpose of the extension part of the study is to help us understand long-term immunity to COVID-19. We are interested in how our immune system might still protect us from COVID-19 even after antibody levels decrease or are no longer detected. We are also interested in how immunity to COVID-19 is different in kids vs. adults.

This study will enroll approximately 200 men and women ≥ 18 years of age who are SARS-CoV-2 PCR positive undergoing home quarantine & approximately 200-1500 immediate household contacts, both male and female, ≥ 1 year of age.

This study will test and follow persons quarantined at home after testing positive for SARS-CoV-2 (COV) and their household members.

The CO-HOST mobile nurse initiates a home visit to the home of the COVID-19 index case after they and their household members (COV-HC) verbally express interest in the study and provide consent or assent as appropriate. At the first visit, nasopharyngeal (NP) swabs and blood are collected from COV and all members of the household (COV-HC) to determine infection status. Additional samples (nasal swabs, saliva, nasal strips), both nurse-collected and self-collected, may also be collected from COV and COV-HC. The nurse will provide specific instructions and training on how to perform self-collected swabs.

Every week, thereafter, COV-HC are tested during the 28 days of the study. If home visits are not possible, then participants will perform self-collected swabs for testing. If COV-HC develops symptoms, they will be referred per standard of care (SOC).

If COV or COV-HC are hospitalized, they will remain in the study for outcome assessment, but without further sample collections.

As part of the extension to the study, the study team will come back to previous enrolled participants' houses for a single visit at about 6 months from when they enrolled in this study. If these participants prefer, they could come to UNC for this visit instead. At this visit, the study team will collect these participants' blood sample and draw up to 10 tsp of blood. The study team will also perform a COVID-19 rapid antibody test, which uses two-three drops of blood from a finger prick. These participants will also be asked to complete a short (5-minute) online questionnaire.

After this visit, if these participants have not already been vaccinated, then the study team will give them the option to participate in one more visit at their house or at UNC within 1-3 months after they receive the COVID vaccine to collect a blood sample (up to 10 tsp). The study team will also repeat the rapid antibody test with another finger prick.

Inclusion Criteria:

COVID-positive index cases (COV):

• Any patient greater than or equal to18 years of age with a positive qualitative nasopharyngeal or nasal swab for SARS-CoV-2 obtained at UNC Hospitals or an outpatient clinic
• COVID-19 diagnosis by positive NP swab
• Willingness to self-isolate at home for a 14-day period
• Living with at least one household contact who is also willing to consent to study follow-up
• Living within reasonable driving distance (<1 hour) suitable for home visits by study team

Household contact of COVID-positive index case (COV-HC):

• Household contacts greater than 1 year of age currently living in the same home as the COVID-positive index case without plans to leave to live elsewhere through the end of the 28-day study.

Exclusion Criteria:

COVID-positive index cases (COV): None

Household contact of COVID-positive index case (COV-HC):

• Previously participated in this study (as index case or household contact)

For the extension part of CO-HOST, study participants greater than 65 years of age who tested positive for acute SAR-CoV-2 infection by PCR or seroconversion (antibody status became positive) during their participation in the first month of the study, will be eligible. They will be excluded if they previously received immunologic therapy (i.e., exogenous anti-SARS-CoV-2 monoclonal antibodies) for COVID-19 infection.

Men and women ≥ 18 years of age who are SARS-CoV-2 PCR positive undergoing home quarantine & immediate household contacts, both male and female, ≥ 1 year of age will all be asked to participate in the study.

De-identified individual data that supports the results will be shared beginning 12 to 24 months following publication provided the investigator/researcher who proposes to use the data has approval from an Institutional Review Board (IRB), Independent Ethics Committee (IEC), or Research Ethics Board (REB), as applicable, and executes a data use/sharing agreement with UNC.

12-24 months after publication

Investigators/researchers who propose to use study data will need to have IRB, IEC, or REB approval and an executed data use/sharing agreement with UNC.