Quebec crossed the milestone of 14,000 deaths caused by COVID-19 on Wednesday, of which nearly 2,400 have occurred in the past three months. Carried by the Omicron variant, the fifth wave will have been not only the most contagious, but also the most deadly for people under 60 since the first wave.
In 90 days, the Omicron wave will have been the cause of approximately 17% of the 14,016 deaths attributed to COVID-19 since the virus appeared in Quebec at the end of February 2020. Data from the Institut national de santé publique du Québec (INSPQ) reveal, however, that the arrival of Omicron and its wave of infections have not only increased the number of people infected, but also changed the profile of the victims.
The fifth wave is the one that has claimed the most victims since the second wave (4897 deaths) due to the large number of people infected. It proved to be four times deadlier than the third wave, in the spring of 2021, and seven times deadlier than the fourth wave last fall.
A changing profile
While the elderly are still overrepresented in deaths, the Omicron wave stands out as the one that caused the most deaths in absolute number (116) among people under 60 since the first wave of the pandemic (143). In comparison, the second wave (fall 2020) had caused 111 deaths, the third wave (March to July 2021) had caused 48 and the fourth wave (fall 2021) had 49 deaths.
“One of the great things about Omicron is that it hit really hard, but it was very short-lived. If it also affected many more young people, we can think that there was a greater mortality in these segments of the population, especially in the unvaccinated groups and people with major risk factors, “explains Alain Gagnon, professor in the demography department of the University of Montreal.
Before the arrival of vaccines between March 2020 and January 2021, more than 90% of people killed by COVID-19 were aged 70 and over. During the fourth wave carried by the Delta variant last fall, no less than 28% of those who died were under 70 years old. Of this number, nine out of 10 were between the ages of 50 and 69.
We can assume that a good part of these deaths occurred in unvaccinated people, if we rely on the vaccination status of people admitted to intensive care that the Ministry of Health regularly revealed this fall.
The picture was quite different with the highly transmissible Omicron variant, which has hit a pool of several million people since December, both vaccinated and unvaccinated. This is because of its greater transmissibility and the lesser effectiveness of the vaccine in stopping the infection. Because of this, the number of people under the age of 60 being swept away by the virus has peaked since the first wave.
“As this fifth wave affected and led to the death of more people, especially in their 50s and 60s, it had a greater impact in terms of the number of years of life lost. It might have an effect on life expectancy. But all of this remains to be analysed, because the effect of the Omicron wave was very brief in time”, specifies the demographer.
It should be noted that since the start of the pandemic, Quebec has used a method of calculating mortality linked to COVID-19 that is different from that used by other provinces and countries. The INSPQ includes in its statistics all people for whom COVID-19 has been identified as the main or secondary cause of death. Other provinces and countries only include deaths from the virus in their data. For this reason, some experts believe that excess mortality figures, comparing actual deaths to expected deaths, are a better indicator of the true impact of COVID-19.
Excess mortality?
New data on excess mortality in Quebec must also be unveiled this Thursday by the Institute of Statistics of Quebec (ISQ). The figures for the month of January suggest a temporary excess mortality in Quebec, while the year 2021 had ended with a lower mortality.
For the month of January 2022, 7,900 deaths were recorded, significantly more than the 7,050 deaths reported in January 2020 during the second wave, and about 13% more than for the pre-pandemic years.
However, these figures include all causes of death, specifies Alain Gagnon. So other factors could have been added to COVID-19 this year, including other respiratory viruses, to explain this extraordinary increase.
“This remains to be dig, because some years, the flu also leads to marked increases in deaths at this time of year,” says the demographer. But it is clear that with the peak experienced by this fifth wave, excess mortality due to COVID-19 is very likely. But we see that its impact was very short. »
In 2020, COVID-19 had become the third leading cause of death in Quebec, after cancer (21,000 deaths per year in Quebec) and heart disease (15,000 deaths). With 4,000 deaths in 2021, the marked slowdown in virus-related mortality could have pushed COVID-19 back several places among the main causes of death in Quebec, but complete data to this effect are still not available.