From smallpox to HIV, here’s how contact tracing helps control outbreaks like COVID-19
The director of the Centers for Disease Control and Prevention has said contact tracing will be a key factor in reopening the United States after the coronavirus pandemic.
A Massachusetts company called Partners in Health is actively searching for qualified workers to help carry out contract tracing in the U.S, while South Korea, Singapore, Hong Kong and Germany have touted its usefulness in tempering COVID-19 outbreaks and reducing the death toll in their respective countries, The Guardian reported.
The director general of the World Health Organization called it “the backbone of the response” in a media briefing on March 16.
But how does it work?
Contract tracing is the process of tracking down people who have been in close contact with an infected patient, McClatchy News has previously reported. Health officials record the names and contact information of those who interact with an infected person so they can be informed of the potential exposure, at which point they might be advised to seek care or self-isolate.
It isn’t a new concept — the public health sector has been using contact tracing for decades to help track and control widespread disease.
Contact tracing and smallpox
Smallpox, for example, had been around since practically the dawn of time before widespread vaccination efforts and contract tracing helped extinguish it, according to the CDC.
“Smallpox no longer occurs naturally since it was totally eradicated by a lengthy and painstaking process, which identified all cases and their contacts and ensured that they were all vaccinated,” the WHO’s website states.
The disease formed a rash on the infected person and was fatal in up to 30% of cases, according to the WHO. Smallpox was also highly contagious as it spread through person-to-person contact and saliva droplets.
But its obvious symptoms helped with contact tracing efforts, according to the Climate Change and Public Health Law Site at Louisiana State University
“Contrary to popular belief, smallpox was not controlled by immunizing every person on earth,” the site states. “It was controlled by extensive contact tracing to find infected individuals. Smallpox could be controlled only because the sores and scars prevented infected persons from escaping detection.”
The disease was officially eradicated in 1979, according to the WHO.
Contact tracing and HIV
Several years later, the CDC recommended using contact tracing to track the spread of HIV, an article from the British Medical Journal in May 1988 says.
By 1987, the process was near mandatory — with or without the patient’s consent.
“If [people infected with HIV] are unwilling to notify their partners ... physicians or health department personnel should use confidential procedures to assure that the partners are notified,” the CDC said.
HIV isn’t the death sentence it once was, but contact tracing is still used to help reduce transmission, according to TheBodyPro, an online resource for people who work around HIV as doctors, nurses or social care workers.
“People who know they live with HIV can seek care and treatment, and early treatment can improve their health and well-being,” their website states. “People living with HIV who begin treatment shortly after diagnosis and take the required medicines every day are expected to live a near-normal lifespan.”
Contact tracing has been similarly used to track and contain the spread of STDs more broadly.
According to a graphic produced by the National Association of STD Directors, contact tracing is a “core public health duty” that can be done anonymously or confidentially — either by the patient themselves or Disease Intervention Specialists (DIS).
“DIS conduct interviews with STD patients to obtain information on sexual partner(s),” the graphic states. “DIS are the backbone of state and local health departments and serve the most critical role in the reporting and controlling the ... spread of STDs and HIV, as well as, hepatitis and tuberculosis.”
Contact tracing and SARS
During the 2003 SARS outbreak in the U.S., contract tracing was again used to control the spread of the respiratory illness.
“Surveillance of contacts of SARS cases is essential to control efforts,” the CDC said in a since-archived post on public health guidance. “Rapid identification, evaluation, and monitoring of exposed asymptomatic contacts and prompt isolation of those who are found to be clinically ill can prevent further transmission of disease.”
At the time, exact information on how long a person remained infectious wasn’t known, but officials recommended some individuals who had contact with the patient before the “onset of illness” also be notified, according to the CDC.
According to an article published in January 2019 in the Computational and Structural Biotechnology Journal, contact tracing was “crucially important” in 2003 and again in 2014 during the Ebola outbreak in Africa.
“With current advances in vaccine development technologies, the role of contact tracing and follow-up control measures in the initial stage of an epidemic becomes especially important,” the article states.
