Saskatoon lab predicted variant spike in sewage study
SASKATOON -- Researchers with the University of Saskatchewan can predict when spikes in COVID-19 and the variants of concern are going to occur by studying wastewater samples.
“Once someone is infected they start shedding virus in their waste immediately, but they might not feel ill for five or six days,” explained John Giesy, professor and Canada research chair in environmental toxicology.
“Once they do, and go and get tested, it could be another three or four days before the results come out. So from the time someone's infected, it could be two weeks before we actually say ‘oh that person's sick’. We pick it up in the wastewater immediately.”
When it comes to the current spike in cases of variants of concern in Saskatoon, Giesy says he and his team saw it coming.
They started picking up the B.1.1.7 variant - which was fuelling an outbreak in Regina - two weeks ago.
At that time, about 60 to 70 per cent of new cases in Regina were due to the variant.
“Well now we're at that, where it's 60 per cent of that variant contributing to the new cases, and that's exactly what our data was showing starting last Thursday.”
Giesy says as information changes almost hourly, the public can log on to their website to get all of their questions answered.
“I think that it's become a very good predictor for us,” said virologist Jason Kindrachuk of the wastewater study.
“The unfortunate reality is then you have a period of time where you basically batten down the hatches and try and get transmission reduced. How do you do that and, especially in the wave of variants of concerns that are transmitting much more broadly and much quicker, it's a pretty arduous task.”
On Tuesday, Health Minister Paul Merriman defended the government’s decision to loosen restrictions in March, saying the arrival of the variants was an unseen variable.
“We made that decision with what we had at that moment, and we were confident with the compliance in that,” he said. “The variant throws everyone in the country and the world a bit of a curveball.”
Kindrachuk says many in the medical community had been asking for preparedness for months, after seeing variants of concern spread very rapidly in the UK, Brazil, and South Africa.
“Infectious disease and virology experts from across Canada, public health experts, have been shouting this since early 2021 and saying ‘We need to get ready, we are not going to have the time to implement all the same kind of slow restrictions into communities to try and get ahead of the variants of concern. They’re just spreading too rapidly.”
Kindrachuk said scientists are still working to figure out why the variant is more contagious.
“It likely is a combination of probably a lower amount of the virus that you need to be exposed to, but also that the time period is likely also shorter that you have to spend within proximity to somebody that is carrying these variants,” he said.
Except for a handful of cases, the main variant of concern confirmed in Saskatchewan has been the B.1.1.7 variant, but Giesy says his concern has shifted to watching for more.
“There's the other variant which is the one originated in Brazil, we call it P1,” he said. “It's now in Vancouver, and the worry about that one is that it seems people who have had it once can get reinfected, and that the vaccines seem to be less effective.”
“We're really worried about that coming into Canada. Right now we have not seen that in the wastewater in Saskatoon, but in my opinion it's only a matter of time.”
Variants from New York and California are also on their radar, says Giesy.
“Hopefully we can give even sooner than two weeks notice to watch for these, and then that helps in our individual monitoring, to be able to focus on it and screen for those.”
Kindrachuk says last year when the weather warmed up, transmission of COVID-19 was drastically reduced outdoors compared to indoors, and that will probably be reflected with the variants of concern — with a caveat.
“Because of the way the variants seem to be able to infect, this idea that they're able to basically better attach to our cells when they come into contact with the respiratory tract, that makes things a bit more difficult,” he said.
“Now just being outdoors doesn't necessarily reduce that risk, you still have to think about this as a common approach where it's, yes, outdoors, plus distancing, plus potentially masking if you're in big groups, so that that certainly has changed.”
Giesy says the B.1.1.7 variant is up to a factor of two times more transmissible than COVID-19.
“I still expect over the summer that we'll have somewhat of a respite,” he said.
Kindrachuk says Canada is in the position of seeing variants of concern outpace the ability to vaccinate.
He says while vaccines appear to be effective against variants of concern, with data showing potential reductions in infectivity in people that are vaccinated, scientists are still determining whether they will be completely effective.
“I think we have some data suggestive that antibodies look like they still recognize the variant with the different vaccines, but we don't have that necessary protective data from real world populations yet, and probably we'll get some of that soon,” he said.
“Let's get vaccines out as broadly as we can to to the people that are likely at the forefront of becoming infected, and really trying to get this nipped in the bud as much as we can.”
A previous version of this story stated the B.1.1.7 variant has been the only COVID-19 variant confirmed in Saskatchewan. There have been nine cases linked to the B.1.351 variant which was first identfied in South Africa.