At the end of September the 4th coronavirus wave peaked and began to decline. With increasing vaccination rates it was widely assumed that this was the last big wave of the pandemic in Canada and the US. However, in recent weeks case counts have plateaued and started moving up. Is this the start of a 5th wave?
Here is the projection for Ontario from the Covid-19 Science Advisory Table.
Here are the Covid cases for different regions in the U.S.
What happened?
One thing that happened is the emergence of new variants. The Delta Plus variant AY.4.2 may be slightly more transmissible than the Delta variant. It has made headway in the UK, outcompeting the Delta variant and now accounts for about 10% of sequenced virus samples there. To date it has not been widely reported in the U.S. or Canada.
Emergence of the ‘Delta Plus’ coronavirus variant
However, in Canada, some other Delta variants have been identified, AY.25 and AY.27. In Saskatchewan, AY.25 is becoming the predominant circulating strain, more than 50% of all cases. In Ontario, AY.25 accounted for 31% of confirmed cases.
What we know about Delta’s newest variants
This chart shows the spread of AY.25 and AY.27 in Saskatchewan.
In various parts of Europe there has been a sharp increase in Covid cases. Germany, which managed the pandemic better than most other countries (except Scandinavia) has more cases and hospital admissions than at any other time during the pandemic.
The extent of the new Delta variants in Europe is not known. The most likely causes for the spike in cases are low vaccine uptake, waning immunity among people inoculated early and growing complacency about masks and distancing after governments relaxed curbs over the summer.
Why is Europe returning to the dark days of Covid?
What should be done?
Here is an assessment from a respected epidemiologist Dr. Colin Furness. He points out a number of “dumb” things that Ontario has done and how they should be corrected.
Allowing full stadium attendance was a sure way to allow further spread. This should be rolled back.
Restaurants are “one of the most dangerous places to be” because there are no regulations or standards for air filtration. The Ontario government has not officially acknowledged airborne transmission of the coronavirus. This will probably not be done by conservative governments in general because it would imply updating their health and safety standards to require many businesses from large warehouses to restaurants to incur the expense of upgrading their heating and cooling systems. However, requiring HEPA filters in spaces where large numbers of people are congregating is really fundamental to controlling the spread of the Delta virus and its variants.
What is the likely outcome?
It was not possible to update the spreadsheet model because there are too many unknowns about the rate of spread and the effect of the new Delta variants. If these new variants do not spread more than 15% more rapidly than the Delta variant and if vaccinations continue to increase, especially now that the vaccine has been approved for children, my expectation is that in Canada and most regions of the U.S. the current increase in cases will be more of a bump than a 5th wave. However in low vaccination areas such as the American South and parts of Europe, the balance could be the reverse and they will experience a full 5th Wave.
