Covid-19: five questions to better understand the second wave

PCR tests for Covid-19 at a hospital in Jammu, India, October 29, 2020. AP Photo / Channi Anand

Text by: Agnès Rougier

8 min

At the time of the second wave of the coronavirus pandemic, are we replaying the same scenario as last spring?

The first wave, which led to lockdowns in France and around the world, provided lessons that could help anticipate the effects of the second.


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  • What do the curves of the first wave tell us


Since the beginning of March, curves retracing the number of cases, hospitalizations or even mortality due to Covid-19, have been produced by several bodies, national and international, and universities, in particular the Johns

Hopkins University of Medicine

in Baltimore in the United States. United States, a true benchmark in this area.

And when we compare the daily death curves for countries in Asia, Europe and North America, we see that at the time of the first wave, they all follow the same slope.

For all countries, the evolution of the number of deaths is exponential, that is to say that the number of deaths from Covid-19 doubles every day until mid-April.

There may be a shift depending on the arrival of the first cases, but the curves are similar.

Then, after a plateau, these curves decrease more or less slowly depending on the containment measures that have been taken.

This is the case for France, Spain, Italy, Germany and China.

We then see that the curves stabilize at a low level during the summer months, then in France in particular, the curve has been rising slowly since the beginning of September, only to sharply accentuate from October 10, the day when all the figures are suddenly quadrupled.

  • What do the numbers say today


The curve is climbing, but we don't know how far yet, and we haven't reached the top yet.

In France as in Europe, the curves show that the pandemic is spiraling out of control.

For France, if we compare the figures of the first and the second wave, we see that we are not yet at the strongest level of the first wave, where we hospitalized almost 2,000 additional people every day, while on October 26, only 817 people were hospitalized.

Regarding resuscitation, we are quickly approaching the daily admission figures last March: 478 people on March 28, for 357 on October 26.

Then, the French were confined from March 17 to May 11, and the effect was very clear, since from the beginning of May, the curves are reversed: there are more discharges of hospitalizations than of inputs.

But still for comparison, and knowing that the effects of the first confinement began to be seen in mid-April, on March 25, so eight days after the start of confinement, 231 people died from Covid-19 in hospital in 24 hours. ;

however, with 288 deaths in hospital on October 27, we can clearly see that the curve is increasing very seriously and that the slope is steep.

  • Do we find more cases because we test more


No, because if that was the case, whether in France or elsewhere, we would have more positive tests, but fewer reported cases, less hospitalization, fewer deaths.

However, it is not the case.

In areas where the rate of positive tests is increasing, there is an epidemic explosion.

The countries that have fewer positive tests are those that have been successful in controlling the epidemic in recent months.

  • Is the geography of the second wave the same as the first wave


The geography of the pandemic has changed.

Today, no French region is spared, the entire territory is seriously affected.

This therefore makes any transfers of patients from one region to another very complicated in the event of hospital overload.

For this second wave, private clinics were involved from the start, which offers more hospitalization and intensive care beds.

However, if the rate of contamination continues to increase rapidly, it is likely that the number of beds will not be sufficient to accommodate both Covid-19 patients and others.

For Pascal Legendre, research director at INSERM, what is most important is respect for barrier gestures: “

 Barrier procedures that are scrupulously followed are currently the only solution for effective protection at the individual level.

The containment solution only delays the epidemic waves, unless it is maintained very strictly and long enough in highly infected regions, as has been the case in China.

In France, the expansion being global, it is too late to target particular regions.

Containment is only really effective if it is imposed in areas that are at the start of an increase.

This should have been done, according to the curves, at least 2-3 weeks before the appearance of a theoretical peak, ideally as soon as the slope starts to increase.


  • Does Covid-19 kill fewer people than seasonal flu



In comparison, worldwide, seasonal influenza is responsible for 290,000 to 650,000 deaths per year.

Regarding deaths due to Covid-19, Johns Hopkins University of Medicine, which records the global status of the pandemic, announced on October 27 1,161,422 deaths due to Covid-19 since the start of the pandemic.

This figure does not include undeclared Covid-19 deaths, nor indirect deaths, that is to say of people who did not seek treatment for other pathologies during the first wave and whose condition is aggravated.

From this point of view, we also expect an upsurge in indirect deaths in the coming months.

A study on Covid-19 mortality

during the first wave in New York, published in

The Lancet

on October 19, estimates that the death rate was 0.7% on average, but almost 1% for the 45-64 age group, 5% for 65-74 years old and 14% for those over 75 years old.

All age groups combined, epidemiologists advance an average mortality rate of 0.5 to 1% for Covid-19, and 0.1% for influenza, the coronavirus could therefore be 10 times more deadly than influenza .

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