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Predicting spread of Delta variant requires ‘solid data’: B.C. independent modelling group

Vaccines key in B.C.’s race against the more infectious COVID-19 variant

While overall cases are continuing to stay low in B.C., an independent modelling group has said the province needs to both keep up vaccinations and improve its data collection in order to stay on the right track.

The B.C. COVID-19 Modelling Group, made up of scientists from three major B.C. universities, released its sixth report on Wednesday, roughly three weeks after B.C. entered Step 2 of its reopening plan, and one week after the province entered Phase 3.

In a video accompanying the report, University of B.C. associate professor of mathematics Eric Cytrynbaum said that while Step 2 did slow the rate of decline in COVID cases, it did not cause a growth in cases.

“We continued to see decline in June and into July,” Cytrynbaum said. “Concerns over the Delta variant still plague us but estimates indicate that Delta is remaining roughly constant or possibly declining slightly – the data is not clear enough to distinguish at this point.”

The Delta variant, or B.1.617.2, is a more transmissible variant that was first detected in India and has spread rapidly around the world. According to the independent modelling group, Delta has show an approximately 10 per cent growth advantage per day compared to the Alpha, or B.1.1.7. A single dose of vaccines has also been found to be less effective against Delta compared to the other variants, coming in at roughly 30 to 35 per cent.

“Delta continues to rise in frequency relative to the other variants,” Cytrynbaum said, even though the overall cases are declining.

“The Step 3 reopening on July 1… could push the Delta growth rate positive or it could be compensated for by ongoing vaccination progress.”

The modelling group has “repeatedly had troubles accessing accurate and updated information about variants of concern.” The group said that the B.C. Centre for Disease Controls’s variant reports are “partial, contain error and are not updated as more data are gathered and corrected.”

Cytrynbaum said the group lacks data from late May to July, “the period of time that really matters for making relevant projections and monitoring existing and emerging variants.”

READ MORE: Rate of more contagious delta COVID-19 variant increasing in B.C. with 500 cases so far

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However, Cytrynbaum said that the vaccination campaign is progressing “really well” and that polls show decreasing vaccine hesitancy. A total of 78.4 per cent of people 12 and older have received one dose and 40 per cent have received their second dose.

He noted that while it’s hard to predict how people’s reactions will change, researchers have noticed a lag behind restrictions lifting and people engaging in previously restricted behaviours.

“At the moment, things like wearing masks indoors and staying home when sick are still important but it seems like it will be some time before everybody is ready to return to the level of interaction currently endorsed by public health policy,” he said.

Step 3, which B.C entered on July 1, removes the mask mandate, although they remain recommended for people who are not fully vaccinated. This step also allows for indoor gatherings of 50 people or 50 per cent capacity and outdoor gatherings of 5,000 people or 50 per cent capacity, whichever is greater in both cases.

Bars and restaurants can also remove limits on table size and casinos and nightclubs can reopen, although both will have some restrictions. Indoor fitness classes are once again allowed with normal capacity levels and spectators can watch both indoor and outdoor sports.

The modelling group presented two scenarios in increased people’s contact rates: one by 50 per cent from June levels and the other by 25 per cent from June.

“A 25 per cent increased in contact rates… we still see a decline in case numbers,” Cytrynbaum said. “If you’re going to go with a 50 per cent increase in contact rates, then you’re going to see a beginning of a growth regime again.”

However, the UBC professor said that even though a 50 per cent rate increase in contacts could see cases spike, there would be enough time for public health officials to switch course.

READ MORE: Feds ‘very eager’ to continue border reopening but unvaccinated tourists not welcome: Trudeau


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