Latest data: France alert to possible second Covid-19 wave

Health authorities in France have repeatedly warned of a“second wave” of the Covid-19 epidemic, and the health minister has described the current virus spread as “worrying”. We look at what the latest data shows.

23 July 2020
A scientist wearing a mask observes a test tube. Latest data: France alert to possible second Covid-19 waveThere are several data indicators that are used to ascertain the state of the epidemic in France. We explain.
By Connexion journalist

On July 20, health minister Olivier Véran said that the “epidemic was restarting in certain areas” in France and that “there is a dynamic of the virus spread that is worrying us” - yet he added that “we are very far from a ‘second wave’”.

However, there have been conflicting reports of how likely a second wave really is.

Read more: 'Real risk’ of second wave of Covid-19

Read more: Covid-19 second wave 'not on horizon' in France

Health body Santé Publique France (SPF) tracks certain indicators across the country and cross-references those with reports of new cases to ascertain the state of the virus across France.

One indicator alone is not enough to judge the spread but, taken together, they can begin to show a full picture.

News service FranceInfo has summarised the major indicators used, and what they really show. We summarise and translate.

Number of cases rising locally

What this measures

This is the number of people infected, out of 100,000 inhabitants, in one week. The ministry for health defines two thresholds - warning levels are raised if more than 10 people per 100,000 are infected. If this number goes above 50, a state of alert is issued.

This is calculated using PCR (polymerase chain reaction) Covid-19 tests, and cross-referenced with the number of positive tests compared to the total number of tests taken.

What the latest data shows

Across mainland France, levels are rising. In the week up to July 12 they rose from 3.9 to 4.3. At this time, one mainland department had reached the level of alert: Seine-Saint-Denis (Ile-de-France), as well as overseas department Mayotte, at 17.89.

Other departments were close; Paris, Ile-de-France (9.87) and Nord, Hauts-de-France (9.15). Alert levels were very high in the overseas department of French Guiana (321.3), and recently rose above the alert threshold in Mayenne, Pays de la Loire (52.72).

Read more: French department on ‘high alert’ after spike in Covid cases

Why we should approach this with caution

The number of cases has a major limitation - it depends on the area in which people are tested, and how many are tested. The more tests done by health authorities, the more new cases are reported, and the higher the case number rises, without the situation necessarily being more alarming in real life.

Testing may also vary greatly from one region to another.

 (Data: FranceInfo / Carto

The “R” level rising

What this measures

This represents the number of people that one infected person will themselves go on to infect, by population. A 2.2 “R” level, for example, means that 10 ill people would infect on average 22 others. When the R number is below 1, this means the epidemic is receding. If it rises above this, it is spreading.

SPF said the R number: "allows us to analyse how the virus is spreading, in the context of an epidemic. In a period of a low spread, the R number is more of an alert indicator, allowing us to identify an unusual situation.”

What the latest data shows

According to figures from July 13, the R number has risen to more than 1.5 in some regions in France, including Provence-Alpes-Côte d'Azur (1.55), but especially in Brittany, where it has reached 2.62, up sharply from 1.07 the week before.

In the overseas department of La Réunion, it is at 2.26. Across France, it is under 1 in three regions, and from 1-1.5 in six others.

Why we should approach this with caution

SPF explains: “The R-value can increase without it necessarily being a sign of the virus increasing.”

For example, the discovery of one outbreak in one particular local area - which is tracked and contained - can lead to more positive tests for that region, without there necessarily being a wider spread.

Read more: Coronavirus: Family reunions spark new clusters in France

This happened in Brittany, where the R-value increased after many more positive tests that were all linked to several specific households.

Similarly, the R number is one calculation that attempts to model and simplify what can sometimes be complex human behaviour. It may be an oversimplification and sometimes does not reflect reality, which is why it should be considered alongside other data.

 (Data: FranceInfo / Carto)

SOS Médecins calls rising slightly

What this measures

Since the beginning of March, the health network has been tracking the number of calls linked to suspected Covid-19 cases reported each day by their doctors. This offers an extra source of medical information, separate from GP surgeries and hospitals.

What the latest data shows

For the week from July 6-12, this number was on the rise for the third consecutive week, SPF said. This rise was across all ages and all regions in mainland France. There was a peak on July 14, with 576 interventions, with a slight drop in the following days.

Why we should approach this with caution

Interventions on suspected cases of Covid-19 only show one part of an eventual epidemic “comeback”. These numbers must be cross-referenced with hospital data for a full picture.

(Data: FranceInfo / Carto)

New hospitalisations not moving much

What this measures

A real “second wave” would be quickly visible in the nation’s hospitals. Increased hospitalisations, and new intensive care admissions, are major indicators that could point to a restart of the epidemic.

What the latest data shows

On a national level, the number of hospitalisations is not rising. Latest weekly data put it at 606, compared to 646 the week before. Yet the number of people admitted to intensive care is rising slightly; from 78 for the last week compared to 73 the week before.

In mainland France - not including Mayotte or French Guiana - these figures are stable, for now.

Why we should approach this with caution

Recent stability of figures is not enough to prove “the absence” of a second wave. If it does occur, this is likely to be seen first in a spike in the number of positive tests, followed by hospital data.

(Data: FranceInfo / Carto)

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