Among the best tools we have to contain the spread of the coronavirus on Nantucket are case investigation and contact tracing. These are proven methods used by health departments across the world to prevent the spread of infectious diseases. Contact tracing works by identifying confirmed cases of COVID-19 and interviewing the patient to help them recall everyone with whom they have had close contact during the timeframe while they may have been infectious. These close contacts are then warned of their potential exposure, provided education, information and support to understand their risk, encouraged to get tested for COVID-19, and given instructions to prevent further spread.

Contact tracing is initiated for every confirmed case of COVID-19 on Nantucket. This work is spearheaded by the Town of Nantucket Health Department, which contracts with Nantucket Cottage Hospital to conduct case investigation and contact tracing. Elizabeth Harris, the infection prevention manager at NCH, has been the lead case investigator and contact tracer for the island’s COVID-19 cases.

Below are some core principles of contact tracing and frequently asked questions to help the community better understand this process:

What is a “close contact”?

A close contact is defined as someone who was within 6 feet of an infected person for a cumulative total of 15 minutes or more over a 24-hour period* starting from 2 days before illness onset (or, for asymptomatic patients, 2 days prior to test specimen collection) until the time the patient is isolated.

* Individual exposures added together over a 24-hour period (e.g. three 5-minute exposures for a total of 15 minutes).

I visited a business where an employee recently tested positive. Why haven’t I been contacted and do I need to be tested?

Just having been in the same establishment as another person who later tested positive for COVID-19 does not necessarily mean you will be contacted by a contact tracer or need to be tested. Unless you meet the criteria to be considered a close contact, your risk of exposure is exceedingly low, and you will likely not be contacted and do not need to be tested. A close contact is not, for example, simply walking by someone at the store who later turns out to be infected, eating at the same restaurant where an infected person may also have dined, or running/biking/walking by someone on the bike path who is later discovered to be infected.

Patient privacy – why can’t I know who may have exposed me?

To protect patient privacy, contacts are only informed that they may have been exposed to a patient with the infection. They are not told the identity of the patient who may have exposed them. Individuals who test positive are told their contacts will be called and encouraged to reach out to them as well.

Instructions for contacts

Close contacts are encouraged to get tested and required to quarantine by staying home, and maintaining social distance from others (at least 6 feet) until 14 days after their last exposure, in case they also become ill. They are instructed to monitor themselves by checking their temperature twice daily and watching for cough or shortness of breath. Contacts who develop symptoms are instructed to promptly isolate themselves and notify public health staff. The 14-day quarantine requirement corresponds to the incubation period of the disease. Even those contacts who are asymptomatic and tested negative for COVID-19 must still self-quarantine for 14 days from their last exposure, per the CDC, and self-monitor daily for symptoms.