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The death count isn’t rising, so we shouldn’t worry? False

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Photo: Evolution of confirmed cases in Quebec, September 28th, 2020 / INSPQ
The number of COVID-19 cases in Québec hasn’t stopped increasing since the end of August. On September 21, it reached the point that the Director of Public Health declared that we entered the second wave. Yet the death and hospitalization curves aren’t increasing. The Rumour Detector wonders if it’s only a matter of time. 
1. A lag between the rise in cases and the rise in hospitalizations 

A lag is inevitable. For example, it takes an average of 15 days  before the most serious cases require hospitalization. Remember that only a minority of cases lead to hospitalization and only a minority of hospitalizations result in death. In June, Western states in the USA, previously spared by the pandemic, saw a jump in their cases. Based on the experience acquired elsewhere, the experts immediately predicted a lag of at least a month between acceleration of infection and a rising death curve. In France, a lag of 2 to 3 weeks was noted more recently. 

2. The unknown factor this fall: young adults  

It hasn’t been established yet whether the lag observed during the first wave is a good predictor of what will happen with the current wave. Contrary to spring, more young people are infected. Since they need to be hospitalized less often and their death rate is very low, this should slow down the upswing in hospitalizations.  

But the virus inevitably will find its way to older people. That will trigger an increase in hospitalizations and deaths. A study by the Centers for Disease Control (CDC) published September 23 shows that in the United States, between June and August, the 20-29 age group accounted for over 20% of the cases. The rise in cases in this age bracket was followed by an increase among people 60 and over. In all the Southern States hit by the pandemic at the beginning of the summer, it took an average of 9 days after cases rose among people in their twenties and thirties before cases increased in the over-60 population. 

It’s also noted that in Alabama, Florida and Georgia, the rise in the 20-39 age group was initially followed by an increase in the 40-59 age bracket a few days later. Finally, this was reflected in the 60-plus population two weeks later. So in these three States, the total lag was about three weeks.  

This September in Québec, the 20-29 age group accounts for a little over 40% of the cases detected. 

3. Testing more means we’re learning more 

Two other factors require us to nuance the forecasts. First of all, there’s a lot more testing (nearly 3 times more in Québec) than in the first wave. The increase in the number of cases may be partly related to that. The week of September 14 averaged 25,000 tests per day. By comparison, in mid-April, we were talking about 8,000 tests per day. In April, priority was given to testing people with symptoms, who undoubtedly had contracted the virus several days earlier. This means there was a shorter lag between detected cases and hospitalizations. Now that we’re detecting cases earlier, these people can be placed in isolation sooner, limiting the spread of the disease. The slower progression of cases then helps the hospitals observe patients and treat them better.  

In addition, since the first wave, medical knowledge has evolved, saving more lives. Ventilation is less invasive (oxygen mask instead of intubation). Corticoids (like dexamethasone) are used to reduce lung inflammations. And there is a generalized use of anticoagulants or drugs like remdesivir to prevent clots. 

4. The second wave is already striking elsewhere 

In Europe, the second wave is already well under way. It arrived sooner than expected, but again, there are questions about the long delay between the rise in the number of cases and the increase in hospitalizations and deaths.  

In France, an increase in the number of cases has been observed since the beginning of August. The arrival of the second wave has been announced since mid-August. According to the data of Santé Publique France, a very slight increase in resuscitation admissions was noted starting at the end of August. But the agency only started talking about an “exponential” increase in its September 24 bulletin. 

In Spain, the expected second wave also struck faster than foreseen. Cases have been increasing since early July. Deaths took a month longer before starting to rise again. But the pandemic seems to be hitting Spain harder. When over 10,000 cases per day were reported in the third week of September, some hospitals in Madrid were almost at maximum capacity. There were already plans to reopen hospitals in the countryside.  

Summing up 
  • Several days may elapse between the time a person is infected and the time he or she is tested.  

  • Infections in young adults can make their way to the older population within an average period of 9 days, according to the U.S. data, and may take up to 1 month. 

  • There can be a 15-day lag before the most serious cases require hospitalization.  

  • The death toll seems to start rising about 1 month after an increase in new cases. But this delay could be longer if people who test positive are isolated faster and more efficiently. 


This article was originally published on the website of L'Agence Science-Presse (French only).


 

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