December 2, 2023

On an overcast afternoon in Halifax, Amy Mullin has wrapped up her remote workday — filled with emails and video calls — and is getting ready for yet another night alone.

She’s going to do virtual yoga with her friend Tato Crisanto and maybe a distanced movie night, with the pair planning to hit “play” at the same time on their respective laptops.

During this time of being stuck inside 24/7, all by herself, Mullin says she feels like a bit of a hypochondriac.

“I sneezed two times in succession, and I was kind of like — oh no — is it starting?

That isolation and anxiety might feel overly familiar, but Mullin isn’t talking about catching COVID-19 or enduring a lockdown in early 2020.

Instead, after years of restrictions and rapid tests and far too many Zoom calls, Mullin and Crisanto both signed up for several weeks alone in separate hospital rooms, all for the sake of science.

The friends are among dozens of Canadians participating in a human challenge trial — a type of medical study that involves purposely infecting people with a particular pathogen. In this case, it’s the bacteria Bordetella pertussis, known for causing potentially deadly whooping cough.

A team member from the laboratory at the IWK Health Centre holds up a colony of Bordetella pertussis. (Lauren Pelley/CBC)

The study, more than a decade in the making, is one of the first of its kind in Canada. It’s run by the Canadian Center for Vaccinology (CCfV) inside an airlocked hospital unit at Halifax’s IWK Health Centre, which features 10 isolation rooms equipped to control infectious agents like pertussis.

The research team’s goal? Better understanding the progression of whooping cough, which affects between 1,000 and 3,000 Canadians each year, in hopes of eventually developing an improved vaccine.

“These types of studies have been done for over 70 years,” said Dr. Scott Halperin, director of the CCfV, “but there has really been a re-emergence of them because of the number of things that one can learn.”

Mullin, a Halifax resident, relaxes in her isolation room, midway through her time participating in a human challenge trial to study whooping cough. (Turgut Yeter/CBC)

Participants undergo regular tests, blood work

Human challenge trials made headlines during the COVID-19 pandemic as researchers used the approach to study the progression of SARS-CoV-2 infections.

They’ve also been used to research diseases from cholera to malaria, and earlier this year, one participant in a trial to study dysentery — an illness known for causing painful stomach cramps and bloody diarrhea — went viral for live tweeting his unpleasant experience.

Not surprisingly, the approach can be controversial — scientists are infecting people on purpose, after all — and there are plenty of hoops researchers need to jump through.

“In order to make this type of study ethical, the pathogen has to be one that is not going to cause, or unlikely to cause, severe disease or death,” Halperin says.

Crisanto has blood samples taken by a nurse, which are sent off to a laboratory to study the progression of their whooping cough infection. (Turgut Yeter/CBC)

Whooping cough can be deadly for infants, but it’s not particularly risky for healthy young adults like Mullin and Crisanto. One of the stipulations for the CCfV study was ensuring the pathogen can be “rapidly and completely cured.” 

In this case, it means every participant gets a few days of antibiotics in the weeks following their initial infection.

“There has to be a rescue medication,” explains Halperin. “There has to be a way that one can treat, so symptoms can be terminated early in the course before it gets too serious.”

Throughout their time in isolation, participants are monitored closely by a medical team, who don full protective gear before heading into each isolation room to take blood work, get saliva samples and other regular tests. 

Dr. Scott Halperin is director of the Canadian Center for Vaccinology (CCfV), which is running a human challenge trial to study whooping cough. (Turgut Yeter/CBC)

“Bear down, hold your breath, and put your tongue to the roof of your mouth,” a nurse tells Crisanto as she preps a nasal swab.

It’s mid-October, and it’s been about a week since Crisanto and Mullin were infected — a process that involved painlessly shooting a dose of the bacteria up their noses with a pipette

The friends are the only two participants in the unit this week, and their isolation rooms are separated by a wall. 

Both are healthy and in their late 20s, and they’re each earning a few thousand dollars to compensate for their time trapped indoors, getting poked and prodded by medical staff.

Mullin, who works at the IWK Health Centre where the trial is being held, first noticed information about the study on her work’s online newsletter and decided to sign up in hopes of paying off some of her student loans.

Mullin has her temperature taken as part of regular checkups by medical staff as she participates in the human challenge trial. (Turgut Yeter/CBC)

But, she quickly explains, it’s also about giving back.

“This is the first time I’m being a big part of medical science,” she says. “Once you are in university, you see what research can look like and how you can participate. This is a nice way to feel like I am doing something helpful.”

That do-gooder feeling mostly makes up for the fatigue, isolation and half a dozen test tubes filled with their blood each time the nurses take a sample — but both Mullin and Crisanto say they knew exactly what they were signing up for.

Living through the pandemic, and previously isolating from a COVID infection, also made this process easier, says Crisanto, who goes by they/them pronouns.

“I have a very stubborn streak in me,” they added, “and so I love a good challenge.”

LISTEN | Hear about CBC News reporter Lauren Pelley’s journey visiting a human challenge trial for whooping cough on The Current:

The Current12:50Researching whooping cough by deliberately infecting volunteers

Researchers in Halifax are deliberately infecting volunteers with pertussis bacteria, known for causing whooping cough, in the hopes of one day developing better treatments and vaccines. It’s a rare type of research that’s been a decade in the making, and the volunteers will be stuck in isolation for weeks. Lauren Pelley, the CBC’s senior health and medical reporter, shares more about the research and journey.

Challenge trials remain ‘complex ethical issue’

While these are willing participants, medical research that involves exposing humans to dangerous pathogens hasn’t always involved this level of precautions and consent.

Indigenous people in Canada have long shared stories of medical experiments being done while they were hospital patients, while invasive, experimental surgeries were among the “commonplace” procedures forced upon people enslaved in the U.S. before the country’s Civil War, according to a survey of old medical journals.

One notable human experiment took place in the late 1700s, after an English physician named Edward Jenner noticed that milkmaids who’d previously caught cowpox didn’t seem to catch smallpox.

He wondered if there was some kind of cross-protection. To test the theory, Dr. Jenner took part of a cowpox sore from a milkmaid’s hand and used it to expose the nine-year-old son of his gardener. Months later, he exposed the child to the virus behind smallpox, and the boy never got sick. 

That early research, risky and unethical as it was, was an early step in the development of the smallpox vaccine — the first one produced against a contagious disease — that eventually wiped out the virus in countries like Canada and the U.S. (Vaccine, by the way, is derived from the Latin word “vacca,” meaning cow.)

Medical ethics have definitely evolved since the days of infecting unsuspecting kids with cowpox.

WATCH: Tato Crisanto and Amy Mullin deliberately caught a disease help science: 

These friends signed up to catch whooping cough and live in isolation

An exclusive look at a lab where Canadians are getting sick on purpose to help scientists study whooping cough — and one day develop a new vaccine.

From the post-Second World War Nuremburg Code on permissible medical experiments — which stated that voluntary consent of human subjects is “absolutely essential” — to a 1966 agreement among the United Nations that prohibits any experiments conducted without the “free consent” of the subject, there are now clear international directives on how to do scientific experiments on members of the public.

In early 2020, a few months into the COVID pandemic, the World Health Organization also released specific criteria outlining its recommended approach to conducting human challenge studies, including a need for “strong scientific justification,” ensuring that the potential benefits outweigh risks and that the selection of participants should be done with “rigorous” informed consent.

Even now, against the backdrop of clear global guidelines, the controversy around human challenge trials remains, says Alison Thompson, an associate professor at the University of Toronto whose research focuses on ethical issues that arise from public health policies.

“It’s a really complex ethical issue,” she says. “There’s definitely not a consensus in the bioethics community.”

Participants have their blood drawn nearly every day to study the progression of their whooping cough infection. (Turgut Yeter/CBC)

Whooping cough went ‘out of control’ after 1980s

The team in Halifax, however, is confident its years of preparation and rigorous safety measures will make its first human challenge trial a success, with potential benefits decades down the line.

Physician and scientist Dr. May ElSherif, whose lab is processing the samples collected from the study participants, says gaining a better understanding of whooping cough is critical. 

“The disease was quite well controlled prior to the 1980s, and then all of a sudden it went out of control again,” she says. “And that is when we started to realize that the vaccines don’t provide lifelong protection.”

Natural infection didn’t provide decades-long protection either, though the illness is only particularly deadly in infants under the age of six months.

And when kids get really sick, that’s when parents hear the distinctive whooping sound that gives the disease its name.

CBC Radio News0:26Child’s whooping cough

An example of a child’s whooping cough from the Government of Canada’s Public Health site

Though there may be hundreds of thousands of pertussis cases occurring globally each year, those community-based infections are difficult to study, ElSherif says. Doing a human challenge trial in a controlled environment instead allows researchers to see how each infection actually progresses, providing potential clues that could be used to develop more effective or longer-lasting vaccines.

“When [infections] happen in the community we don’t know the timing, we don’t know when it started, we don’t know when the individual was exposed, we don’t know how much bacteria caused the infection — there are so many unknowns,” ElSherif said. 

“All of these unknown pieces are what we make feasible using a challenge study.”

Physician and scientist Dr. May ElSherif, whose lab is processing all the samples collected from the study participants, says gaining a better understanding of whooping cough is critical. (Turgut Yeter/CBC)

Years of research ahead

The Halifax research team is hopeful this early trial will be the first of many, both to better understand pertussis infections and potentially look at other pathogens in the future.

As for Mullin and Crisanto, neither one ended up getting any serious symptoms like the telltale cough, though Crisanto’s test results did show they had an active infection — which meant they had to stay in the unit for a few extra days to be further studied.

This phase of the trial was meant to gauge just how much pertussis bacteria it takes to get someone sick, giving the researchers insight into the optimal dose for future rounds, making the friends’ participation just one piece of the team’s slow-and-steady, years-long research.

Mullin practises yoga inside her isolation room at the IWK Health Centre in Halifax roughly a week after being infected with pertussis. (Turgut Yeter/CBC News)

Both will be coming back to the challenge unit for periodic followup appointments as well, along with the other early participants.

It’s a small but important way to help scientific progress, Mullin says, though she acknowledges not everyone would voluntarily sign up for weeks of isolation and the possibility of an active whooping cough infection.

“The amount of times people have been like, ‘You could not pay me enough to intentionally get pertussis,’ and I was like, ‘That’s you — and I’m different.'”


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