COVID-19 and contact tracing

Public Health Essentials! A blog by the Snohomish Health District.

COVID-19 and contact tracing

By Kari Bray / Snohomish Health District

Just as testing is a key piece of the long-term response to the novel coronavirus disease (COVID-19), disease investigation and contact tracing are crucial, as well.

These topics have generated a number of questions, as well as concerns and rumors. We aim to address some of those here.

What is disease investigation and contact tracing?

When there is an outbreak of illness, disease investigators work to identify possible sources, track the spread, and notify people who may be infected before they further spread the disease or become severely ill. It’s a routine part of public health efforts for containing outbreaks and limiting the spread of tuberculosis, sexually transmitted diseases, hepatitis, and other communicable diseases in our communities. This has been a part of daily public health operations for decades.

Step one is case investigation, where a person who has the disease is interviewed. During the current pandemic, that means anyone who has tested positive for COVID-19. An interviewer asks questions like date of birth, address, gender at birth, race, and ethnicity. They may ask about where you work and what your job duties entail, travel history, as well as the nature and timing of the illness. They will not ask for things like your social security number, financial information, or immigration status.

Disease investigators also ask with whom an ill person had close contact. The goal is to identify people who were exposed. For COVID-19, that’s generally anyone who has lived in the same home or been within six feet of someone with COVID-19 for 10 minutes or more while the person was infectious.

This kicks off step two, which is contact tracing. Public health staff or volunteers call the close contacts to notify them of possible exposure and provide guidance on how long to quarantine, what symptoms to watch for, and what to do if they become ill. Public health workers are trained and required by law to not reveal the identity of the person who may have exposed the contact, and to protect the personal health information of the people they call.

When is the Snohomish Health District starting contact tracing?

Contact tracing for COVID-19 isn’t new. It started on January 20, when we received notification of positive test results for the first reported case in the U.S.

As for contact tracing overall, public health nurses and other Health District staff do tracing for outbreaks of many diseases. Some examples you may have heard about in recent years include measles, mumps, whooping cough, and hepatitis. And there are disease intervention specialists who work to identify, notify and provide resources to partners of patients with sexually transmitted diseases. The District also has a program focused on preventing the spread of tuberculosis. That work involves contact tracing, too. In fact, the roots of public health in Snohomish County go back more than 100 years to efforts by Red Cross nurses to contain tuberculosis.

So it’s important to remember that contact tracing is not a new effort, not for COVID-19 or for other diseases. It is part of the DNA of public health.

But COVID-19 is different.

Yes, it is. The scale of this pandemic means that contact tracing is a much larger effort that is needed all over the county, state and country.

The newness of this disease and the lack of both immunity in the population and pharmaceutical interventions – like a vaccine or a proven treatment – also make it unique and challenging. Unlike measles, where high rates of vaccination can help slow or stop the spread in a community, we don’t have widespread immunity to COVID-19. We’re also still learning about the virus and the disease. For illnesses we’re familiar with, there’s a clearer list of symptoms and an understanding of how the illness typically spreads, how long someone is contagious, how long the virus is viable on surfaces, who is most vulnerable, etc. With COVID-19, these are things we continue to learn about.

The other thing that makes COVID-19 contact tracing different from other illnesses is measures like Stay Home, Stay Healthy and social distancing that are in place to help curb its spread. This puts a lot of weight on the success of investigation and tracing to allow more businesses and activities to resume while avoiding a substantial increase in cases that would threaten hospitals’ capacity to provide acute inpatient care. Quick detection and containment of outbreaks are also critical toward achieving this objective.

So how many contact tracers do you need?

This is a long-term effort, and the exact number of staff and/or volunteers dedicated to contact tracing will likely fluctuate throughout as case numbers change.

The Health District has increased training and reassigned staff from other programs, hired new staff, and worked with volunteers through our Medical Reserve Corps to amplify our contact tracing work.

Training is ongoing for temporary employees and volunteers with our Medical Reserve Corps to help boost that capacity from about 10 full-time equivalent positions as of early May to about 30 full-time equivalent positions for disease investigation and contact tracing. If cases and contacts get beyond the capacity of the Health District, the Washington State Department of Health (WA DOH) provides support and can draw on additional help, such as the National Guard staff who have been trained for this work by WA DOH and will be supervised by state or local public health workers.

What happens if I test positive?

People who test positive for COVID-19 can expect a phone call from the Snohomish Health District or the Department of Health, often followed by an email with information on isolation and illness prevention.

The phone call is to make sure you are aware of the positive test result and provide guidance on how long to isolate from others and how to prevent the spread of illness. The disease investigator also does an interview and will ask questions to identify others who may have been exposed. Then periodic follow-ups will be done via text or phone call to support adherence to home isolation directives, answer questions, or make referrals as necessary. Generally, the length of isolation is at least 10 days from the onset of symptoms and for at least 3 days after fever has resolved and cough or other symptoms have improved.

What happens if I’m a close contact of a case?

If you are called by public health because you’ve been identified as someone who was in close contact with a confirmed case, you’ll be asked to quarantine at home. That means staying home and away from others for 14 days, while monitoring for symptoms of illness. You’ll be provided with information on what symptoms to watch for, and if you develop those symptoms, we encourage you to contact your medical provider and to get tested for COVID-19.

If you develop symptoms or if you test positive, you will be asked to continue to stay home and away from others until at least 72 hours after your fever is gone (without fever-reducing medication), other symptoms are improving, and at least 10 days have passed since the start of symptoms.

Let’s talk about what doesn’t happen.

Rumors and misinformation have caused fear for some about what happens to themselves and their families if they are identified as either a case or a close contact.

First of all, the case interviews and contact notifications are almost always done by phone. Public health staff or public health-supervised National Guard members are not being sent to houses to round people up. Our priority is reducing the spread of illness, which means we want you to stay home and avoid in-person contact with others, including our disease investigators.

You may also have seen rumors about people being forced into isolation and quarantine facilities. If you do not have a safe place to stay during a COVID-19 illness due to unstable housing or inability to maintain distance from vulnerable members of your household, the county does have a location available. However, the preference is for people to isolate or quarantine at home. We do ask that you maintain distance from household members during your illness, but you can do that by keeping to your own room and limiting contact in shared spaces.

There has also been concern about children being taken away from parents or guardians if the child or parent becomes ill with COVID. If there is COVID in a household where children are present, the same steps should be taken as in other households – stay home and away from others, practice good cleaning and hygiene, and call your doctor if you (or your child) develop symptoms or if they worsen. It is a good idea to make a plan for who would care for your children if you were to become severely ill and needed to be hospitalized. We encourage you to talk to family, friends or neighbors you trust.

Our staff and volunteers also are trained to protect patient privacy. Information is provided in aggregate on our case counts page, but we do not provide personally identifiable health information.

How can I help with contact tracing?

1. Volunteers are welcome through our Medical Reserve Corps. They can support us with a variety of public health efforts, including drive-thru testing, call centers, and contact tracing during COVID-19. Learn more or sign up at

2. For paid positions, including temporary positions needed during this emergency, you can monitor for job postings at

For new staff or volunteers brought on to help with contact tracing, a three-hour course is required to start training. The course is through the Association of State and Territorial Health Officials.

Additional training is required before they begin actually doing contact tracing with the Health District. They also shadow public health staff conducting contact investigations and have closely supervised training calls prior to operating independently.

Please remember that one of the best things you can do to help with contact tracing and the overall response to COVID-19 is to continue following guidelines to keep yourself and others healthy. By limiting close contact with others, you reduce the likelihood that you will become ill and you reduce the number of contacts in the event that you do. This helps keep contact tracing manageable for our team and others working to address this pandemic.

The Public Health Essentials! blog highlights the work of the Snohomish Health District and shares health-related information and tips.

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