But professionals and volunteers involved in the efforts have struggled to get people to answer the phone and share their contacts and movements. Now, with the virus surging across the country, they are also struggling to keep up with the huge number of new cases, making contact tracing vastly more difficult and less and less effective.
Some public health experts now believe that, at the very least, testing and contact tracing need to be scaled back in places with major outbreaks. Many states have increased COVID-19 testing, which increases the caseload for investigators and contact tracers.
“Right now, there are far too many people getting sick for contact tracing to be the tool that manages the epidemic and keeps it from growing,” says Crystal Watson, who has a doctorate in public health and is a senior scholar at the Johns Hopkins Center for Health Security.
New Hampshire announced this month that it would scale back its contact tracing efforts and focus on full case investigations involving high-risk populations, including health care workers, communities of color, and people in group living spaces. The move comes after a record number of new daily cases -- 323, almost 100 more than the previous day -- and reports of delays in contact tracing.
"Contact tracing is part of a containment strategy to stop the spread of COVID-19, but it is one, and only one, layer or intervention for helping to prevent the spread of COVID-19,” State Epidemiologist Benjamin Chan, MD, told New Hampshire Public Radio. “As community transmission increases, it becomes a less effective strategy of identifying and breaking the chains of transmission."
Local health officials in parts of Wisconsin and Virginia are asking the public to isolate themselves immediately if they test positive for COVID-19 and to tell their contacts that they may have been infected.
“Despite increased staffing and the assistance of the state contact tracing team, the number of people to be contacted has now exceeded the capacity of the [Wisconsin] Rock County Public Health Department. We are no longer able to conduct the same level of contact tracing that we would during a typical outbreak,” Health Officer Marie-Noel Sandoval said in a news release last month.
Contact tracers are also busier because the CDC recently changed the metric for close contacts -- from those who were within 6 feet of someone with the virus for 15 minutes or more, to being that close for a total of 15 minutes during a 24-hour period.
“So, people who last week would not be considered a close contact because they have 5 minutes of exposure to someone a few times a day, are now considered a contact. The number of recommendations for people to quarantine is going up. In addition, we have a true increase in the number of cases,” Cynthia Morrow, MD, director of the Roanoke City and Alleghany Health Districts in Virginia, said during a recent news briefing, TheRoanoke Times reported.
“That constellation of events indicates that our staff, who have been working so hard the last few months, are working even harder. And I think that’s part of our appeal for people to really help us,” Morrow said.
Wide Variation in Participation
The decision to scale back in some states is also fueled by a lack of success in reaching contacts.
“There is a lot of variation across jurisdictions in how willing people are to participate in contact tracing and how successful contact tracing is,” says ,” Carolyn Cannuscio, who holds a doctorate of science and is an associate professor of family medicine and community health at the Hospital of the University of Pennsylvania in Philadelphia.
In South Florida, the “connection rate” this summer reached a low of 17%, which meant that at least 80% of infected cases were not told to isolate and their contacts were not reached either, according to Miami Beach Mayor Dan Gelber.
He and four other Florida mayors held a virtual news conference Nov. 18 to urge Gov. Ron DeSantis (R) to change direction and beef up the state’s testing and contact tracing efforts, and use digital apps developed by Google and Apple. So, far the governor has not responded.
“I suspect in some states, including Florida and Georgia, that decisions were made at the governor level to not invest as many resources as other states. In some parts of the country, contact tracing has been politicized, which affects how much those states scale up and the willingness of population to engage in and cooperate with it. I suspect this is a significant factor,” says Watson.
Delaware, on the other hand, reports that its teams reached 63% of their COVID-19 cases within 24 hours for the past 6 months, and completed interviews with 77% of those cases. But 20% of those infected didn’t name any of their contacts, and only 49% of the named contacts were reached, according to the state’s COVID-19 dashboard.
A more positive story is in Philadelphia. “Our contact tracing team reaches 80% of the [named contacts] we call, and they complete 80% of the interviews,” says Cannuscio, who leads contact tracing efforts at Penn Medicine for patients and faculty in collaboration with the Philadelphia Department of Public Health.
She pointed to a program in Maine that has a 96% success rate in getting contacts to agree to enroll and be automatically monitored to see if they develop COVID-19.
CDC Recommends Priorities for Contact Tracing
The CDC now recommends that overwhelmed contact tracing teams concentrate on household members of infected people, including those who provide care for or visit the person diagnosed with COVID-19. They updated their guidance Nov. 23.
That isn’t surprising, given that health officials have been warning against family gatherings during the holidays.
The most common place for clusters of infections is in a home among residents, according to a Massachusetts Department of Health report. The number of cases and clusters in households was significantly higher than other spots for clusters or cases connected to them, including child care centers, nursing homes, prisons and jails, industrial sites, hospitals, and social events.
The CDC says the next priority for contact tracing is high-risk people such as older adults, people with certain medical conditions, and people who may need to take extra precautions against COVID-19; or who are part of a cluster (two or more cases connected in time and place); or who were exposed to COVID-19 within the past 6 days.
Rehiring Contact Tracers
Some states, like Massachusetts, reduced their contact tracing workforces last summer after the rate of positive cases declined. Now they are scaling up again in response to the surges. The Massachusetts Contact Tracing Collaborative is recruiting more people, especially those who speak languages other than English. The state is also planning to pilot a digital contact tracing program that uses Bluetooth technology to track and warn people who may have been exposed to the virus, MassLive reports.
“Given the number of increasing cases in Massachusetts, we are starting to flex the role of the contact tracers to contact individuals to triage cases and contact people every other day,” Marylou Sudders, secretary of the state Health and Human Services office, said at a news conference in November.
Virginia's regional surge teams are close to being set up, with training for new hires starting this week, Erin Beard, a spokesperson for the Virginia Department of Health, said in an email.
Local health departments are hiring more people to support case investigation and contact tracing efforts, Beard said.
“Most states haven’t reached their workforce goals -- this challenge needs a national response rather than one powered by individual jurisdictions, such as a highly trained force that could be deployed to areas of highest need and rapidly intervene,” says Cannuscio.