Researchers in Ottawa are embarking on a 10-month study to answer critical questions about how individual immune system responses to the novel coronavirus differ and how soon after infection a patient might be at risk again.
The team’s findings could have major implications for vaccine research and help to predict an individual’s risk of developing serious complications related to COVID-19, but one of the study’s lead researchers warns the findings won’t lead to any ironclad declarations of COVID immunity among recovered patients.
A team of researchers with the University of Ottawa and The Ottawa Hospital will study COVID-19 antibody and T cell responses from 1,000 subjects over the next 10 months. In an infection, T cells target infected cells and help to stimulate B cells, which then produce antibodies to neutralize pathogens and label them for disruption.
Half of the study participants will be people who have tested positive for the novel coronavirus, while the other half will be a surveillance cohort of front-line workers and other people who would have a high risk of exposure to the virus but might not have been tested for infection.
The goal will be to test how long these subjects’ immune systems produce antibodies capable of neutralizing the pathogen after the initial infection.
Dr. Marc-André Langlois, professor with the University of Ottawa’s Faculty of Medicine, tells Global News the study idea was first proposed in the spring to answer an integral question in combating the novel coronavirus pandemic.
“Since the very beginning of the epidemic, we were quite sure everyone who is infected will make antibodies, but how long will those antibodies last and how long will that protection last?”
The question of COVID immunity has been in the spotlight in recent weeks, with U.S. President Donald Trump proclaiming to be immune to COVID-19 after testing positive and subsequently recovering from the virus.
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Health experts have said Trump’s messaging, which has included assertions that others who tested positive for the coronavirus are also immune, are “extremely dangerous.” Recent examples of individuals twice testing positive for the virus are also throwing those claims into doubt.
Langlois says Trump is a “complicated case” because of the experimental treatment he was given, which saw him treated with external antibodies rather than just developing them on his own.
Typically, an infected individual’s immune response will develop its own antibodies and T cells — the immune system’s one-two punch — to combat the pathogen. T cells and B cells can then form a memory of sorts that recognizes familiar pathogens and triggers a stronger response the next time a similar virus enters the immune system.
“The basis of long-term immunity is having these sentinels that remain in your lymph nodes and your bone marrow so that if you’re re-exposed to the pathogen, you will be able to produce a fresh lot of antibodies on your own. These will be produced by your own cells and these will protect you,” Langlois explains.
“In the case of Trump, those antibodies came from an outside source and neutralized the virus. It is unknown if he has any memory B cells or memory T cells,” he says.
But even in a typical immune response scenario, which can include an internal response triggered by an external vaccine, memory cells tend to fade after a period of time.
Because of the natural waning immunity to these antigens, vaccinations often require booster shots to restimulate the immune response for the long-term.
One of the most integral takeaways from the upcoming research, then, will be establishing the window of time when a booster would be needed for anyone receiving the upcoming COVID-19 vaccines so that the immunization sticks.
The convalescent cohort — those who have had lab-confirmed cases of the novel coronavirus — will be monitored over the next 10 months for their levels of neutralizing antibodies to help determine when the post-recovery immunity typically fades.
The other 500 participants who were at high risk of exposure but did not get a positive test will be tracked for their own immune responses.
Researchers are betting that a portion of the group, maybe five to 10 per cent, might have been infected early on in the pandemic and shown no or mild symptoms, making their immune responses especially important for determining what gives an individual more effective protection against the virus.
“We’ll be able to monitor and study how these immune system responses are different from person to person and try to find predictors of disease severity,” Langlois says.
By analyzing blood samples for neutralizing antibodies from these two cohorts, Langlois says the study’s findings could help determine a minimum threshold of protection that could then predict whether someone’s immune system is likely to keep them safe from infection or more serious complications related to COVID-19.
He cautions, however, that immune responses vary greatly from person to person, and that the study won’t give a standardized timeframe of immunity after a coronavirus infection. At best, the study could provide probabilities of infection based on various individual predictors, such as genetic markers.
“We’ll never know for sure if they can get reinfected or what the severity of that infection is,” Langlois says.
“It will never be a black and white scenario where we say, ‘Here’s your stamp — you’re protected.’”
The Ottawa-based team, which includes epidemiologists, clinicians, legal and ethics experts, hopes to publish findings from the study in a year’s time, but Langlois notes that some research updates will likely be published as they go, given the time-sensitive nature of the work.
The researchers are currently looking for more participants in their study.
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