In bid to beat virus, health workers become sleuths
Your job is to self-isolate. The job of public health workers in Quebec is to trace every person who has been in close contact with someone infected with COVID-19 so they can be warned before they spread the disease to others.
The latter group has the more difficult job.
Yet the work of both “teams” — the public and public health — is needed to slow down the transmission of the new coronavirus enough that the health care system doesn’t get overloaded with cases, said Eric Litvak, medical chief of infectious disease prevention and control at the province’s regional public health department in Montreal.
“To slow it down, we have two means as a society,” he said of the battle to slow the spread of COVID -19.
“The first is to confine people and put all our activities on pause, which has been done. But that won’t be sustainable in the long term. And that’s where public health plays an important part because the other tool to slow down transmission and keep it at a low enough level is all this work of investigating cases and tracing contacts.”
By tracing people who have been in contact with an infected person, Litvak said, “we can warn those people to remain isolated at home and to watch their symptoms so that they do not become themselves a vector of new transmissions to other people.”
The Montreal public health department alone has an army of several hundred people who are conducting epidemiological investigations that include contact tracing seven days a week, from 8:30 a.m. to 10 p.m. and beyond.
They are assisted by medical students and school nurses who are available while the province’s schools are closed.
It’s an epic task, but Montreal public health has managed to investigate 95 per cent of the more than 4,400 confirmed cases of COVID-19 on the island, Litvak said. A handful of them can’t be reached, he said, usually because of incorrect contact information.
On any day, 56 people from the pool of hundreds carry out the investigations. They’re supported by a team of other experts looking at the new science related to COVID-19 and working on improving the process, Litvak said.
The volume of COVID cases is high now, so it’s difficult to tell if all the investigations are being launched within 24 hours of a laboratory notifying the public health department of a positive coronavirus result, he said. But it’s as close as possible, he said.
A close contact considered at risk is any person who was less than two metres from the infected person for 15 minutes or more. Think workplace, a wedding, a shopping centre, a dinner with friends or family.
The epidemiological investigation has, in fact, two objectives:
To determine where the infected
■ person might have contracted the virus. So the person will be asked if they travelled recently, were in contact with a known case of COVID-19 or have been in a hospital or another public place where there were known cases. If there’s no link to a prior case, it’s considered a community transmission. The incubation period for COVID-19 is up to 14 days, so investigators will trace a person’s activities going back 14 days before their symptoms began.
To determine where the infected
■
person might have gone while they were contagious and, as a result, who else they might have exposed to COVID-19. That’s the tracing of close contacts, and it’s become more important than determining where the person became infected, Litvak said. The infected person provides investigators with names and phone numbers of people they came into contact with while contagious.
The current guideline is to investigate who the infected person came into close contact with during the 24 hours before they developed symptoms and up to the time they started self-isolation. But as new evidence gathers about the novel coronavirus, Litvak said, the 24-hour time frame might soon be expanded.
As a second step, investigators get in touch with the close contacts to warn them to self-isolate for 14 days, regardless of whether they have symptoms, Litvak said. If these close contacts develop any symptoms themselves during that time, they’ll have to stay in self-isolation longer.
Investigators also intervene in group settings to get in touch with people who aren’t on the infected person’s list but may have been in close contact, such as in a workplace or a public place.
A close contact considered at risk is any person who was less than two metres from the infected person for 15 minutes or more.
“We have two brake pedals” on COVID-19, Litvak said. One involves the population measures that prohibit gatherings and require individuals to keep a minimum distance of two metres apart. The other “brake” is the public health action of investigating cases and tracing contacts.
Eventually, when the government begins releasing the first brake pedal by gradually removing controls on gatherings, Litvak said, “it’s going to be critical for us to keep pressing on the second one.”