EVERETT — Due to the increasing number of cases, disease investigators in Snohomish County are no longer notifying people who may have come in close contact with a confirmed COVID-19 patient and instead will rely on patients to make others aware of the potential exposure.

“We are still contacting all confirmed cases, which includes anyone who has a positive test result as well as anyone who is a close contact of a confirmed case and develops symptoms of respiratory illness,” the Snohomish Health District announced Saturday on its website.

The change raises concerns about the ability to track and contain the spread of COVID-19. As of 4:30 p.m. Thursday, the health district reported 362 cases had been confirmed in Snohomish County, including at least seven deaths. That’s up from 60 confirmed cases on March 11.

Without interdiction, experts predict the number of confirmed cases to double every five to seven days.

“As you can imagine we have a supply and demand problem in terms of the scope of this event and the resources we can bring to bear on it,” said Dr. Chris Spitters, the district’s interim health officer.

Spitters said the change to the notification policy came after consultation with the state health department and the U.S. Centers for Disease Control and Prevention, both of whom are on site at the health district.

Typically, health department workers try to interrupt transmission of disease early on, by identifying and isolating those who are infected and their contacts, so they in turn can be isolated. They then seek the close contacts of those people and repeat the procedure until the spread is stopped.

An average infected patient might have close contact with eight to ten people, Spitters said, such as housemates, close friends and coworkers.

For the coronavirus, U.S. Centers for Disease Control and Prevention guidelines define “close contact” as anyone who has been within 6 feet of a person infected with the virus for a “prolonged period of time, as well as those who have had direct contact with the infected person’s secretions.”

On average, a person with the coronavirus will infect 2½ others, Spitters said.

“Our goal is to get that to less than one,” he said. “If we do, over time, incidents will decrease.”

Since January, when the first person diagnosed with the disease in the United States was admitted to Providence Regional Medical Center Everett, two full-time and one part-time epidemiologist at the health district have worked seven days a week going through hundreds of cases, each of which can take a full day to investigate, administrator Shawn Frederick said this week.

The investigations include identifying, listing and notifying potential contacts, providing them medical guidance, and in some cases, quarantining or isolating the highest risk contacts either at home or in a hospital. They also include regular follow-ups to monitor symptoms and test for infection, if necessary.

“All that takes a fair amount of time,” Spitters said.

The district decided it was better for its staff to focus on ensuring the growing number of people infected with the virus had been interviewed, had been instructed about their obligation to avoid other people and had identified a health care provider, should any problem arise.

Under the new protocol, confirmed COVID-19 patients will receive guidance from public health staff and an official district letter to provide to those with whom they may have been in close contact. The letter explains what the close contact needs to do.

Now, instead of being contacted by a caseworker, those who’ve come in close contact might receive a message by phone, email or mail notifying them they need to self-quarantine for 14 days.

If the person with the confirmed case identifies close contacts who are in a high-risk category, the health district may reach out to those contacts. Those include healthcare workers, first responders and those who are 60 or older, have underlying health conditions or compromised immune systems, or are pregnant.

In cases where patients might be hospitalized or unable to notify their close contacts, the district will seek another person close to the patient to handle the notifications, or the district will do it, Spitters said.

Jared Baeten, vice dean of the School of Public Health and professor of Global Health, Medicine and Epidemiology at the University of Washington, said the district is “rightly directing its resources for maximum public health benefit.”

“I’m incredibly impressed with how thoughtful and nimble the county and state public health agencies have been in responding to an epidemic that is shifting around us all daily,” Baeten said.

Spitters said the district will continue to evaluate the situation.

“If we get red flags this isn’t going to work … then of course were going to go about doing it ourselves,” he said.

Phillip O’Connor: 425-339-3480; poconnor@soundpublishing.com.