Estimating the burden of SARS-CoV-2 in France, and its implication: the risks are still huge

Fig. 1 COVID-19 hospitalizations and deaths in France.

(A) Cumulative number of general ward and ICU hospitalizations, ICU admissions and deaths from SARS-CoV-2 in France. The green line indicates the time when the lockdown was put in place in France. (B) Distribution of deaths in France. Number of (C) hospitalizations, (D) ICU and (E) deaths by age group and sex in France.

Abstract

France has been heavily affected by the SARS-CoV-2 epidemic and went into lockdown on the 17 March 2020. Using models applied to hospital and death data, we estimate the impact of the lockdown and current population immunity. We find 3.6% of infected individuals are hospitalized and 0.7% die, ranging from 0.001% in those less than 20 years of age (ya) to 10.1% in those greater than 80ya. Across all ages, men are more likely to be hospitalized, enter intensive care, and die than women. The lockdown reduced the reproductive number from 2.90 to 0.67 (77% reduction). By 11 May 2020, when interventions are scheduled to be eased, we project 2.8 million (range: 1.8–4.7) people, or 4.4% (range: 2.8–7.2) of the population, will have been infected. Population immunity appears insufficient to avoid a second wave if all control measures are released at the end of the lockdown.

We find that 3.6% of infected individuals are hospitalized (95% CrI: 2.1–5.6), ranging from 0.2% (95% CrI: 0.1–0.2) in females under less than 20ya to 45.9% (95% CrI: 27.2–70.9) in males over 80ya. Once hospitalized, on average 19.0% (95% CrI: 18.7–19.4%) patients enter ICU after a mean delay of 1.5 days (fig. S1). We observe an increasing probability of entering ICU with age—however, this drops for those over 70ya. Overall, 18.1% (95% CrI: 17.8–18.4) of hospitalized individuals go on to die. The overall probability of death among those infected (the Infection Fatality Ratio, IFR) is 0.7% (95% CrI: 0.4–1.0), ranging from 0.001% in those under 20ya to 10.1% (95% CrI: 6.0–15.6) in those over 80ya and table S2). Our estimate of overall IFR is similar to other recent studies that found values of between 0.5 and 0.7% for the Chinese epidemic.

We find men have a consistently higher risk than women of hospitalization (RR 1.25, 95% CrI: 1.22–1.29), ICU admission once hospitalized (RR: 1.61, 95% CrI: 1.56–1.67) and death following hospitalization (RR: 1.47, 95% CrI: 1.42–1.53).

Y HENRIK SALJE, CÉCILE TRAN KIEM, NOÉMIE LEFRANCQ, NOÉMIE COURTEJOIE, PAOLO BOSETTI, JULIETTE PAIREAU, ALESSIO ANDRONICO, NATHANAËL HOZÉ, JEHANNE RICHET, CLAIRE-LISE DUBOST, YANN LE STRAT, JUSTIN LESSLER, DANIEL LEVY-BRUHL, ARNAUD FONTANET, LULLA OPATOWSKI, PIERRE-YVES BOELLE, SIMON CAUCHEMEZ
PUBLISHED ONLINE13 MAY 2020

DOI: 10.1126/science.abc3517

Implications for Australia and other countries:

This recent report allows a conservative estimation of the potential effect of uncontrolled coronavirus spread in Australia based on measurements of infection and immunity in France.

Starting with the total population of Australia of being 25.5 million people and assuming an uncontrolled epidemic could attack 70% of the population before petering out, which is consistent with both epidemiology theory and observation of high attack rates in Bergamo, Italy, SARS coronavirus 2 could infect as many as 17.85 million Australians.

Assuming an infection fatality ratio of 0.7% (reported in the French paper which is probably an underestimate because of unreported excess deaths) an unconstrained COVID19 epidemic could kill 125 000 Australians.

Given the French experience that hospitalisations are 3.6% of infections, an unrestricted COVID19 epidemic in Australia could result in 643 000 hospitalisations.(corrected)

These are sobering numbers and are conservative estimates relying on simple observations and a minimum of predictive modelling.

The infection fatality ratio (0.7%) reported in the paper is similar to other studies emerging from the application of antibody testing which are now providing more realistic estimates of total numbers of infections both symptomatic and as symptomatic.

Such evidence of relatively low total attack rates in the epidemic are emerging for Geneva, Switzerland,  Spain, New York City. and other regions of the USA . These sobering numbers  indicate the potential for ongoing infections and second waves to greatly add in terms of scale of impact to the current tragic impact documented disease and mortality from coronavirus.

Update 2.
Similar overall findings in Geneva

Repeated seroprevalence of anti 1 -SARS-CoV-2 IgG antibodies in a population-based sample

medRxiv preprint

https://doi.org/10.1101/2020.05.02.20088898.this version posted May 6, 2020

It is made available under a CC-BY-NC-ND 4.0 International license

Silvia Stringhini 1, 2, 3, Ania Wisniak 4, Giovanni Piumatti 1,8, Andrew S. Azman 5, Stephen A.

Lauer 5, Hélène Baysson 2, David De Ridder 2, Dusan Petrovic 1,3, Stephanie Schrempft 1, Kailing

Marcus 11, Sabine Yerly 6,9, Isabelle Arm Vernez 9, Olivia Keiser 4, Samia Hurst 7, Klara M.

Posfay-Barbe 2,10, Didier Trono 11, Didier Pittet 12, Laurent Gétaz 1,2, François Chappuis 1,2,

Isabella Eckerle 2,6,9, Nicolas Vuilleumier 2,6, Benjamin Meyer 2, 13,Antoine Flahault 1,2,4, Laurent

Kaiser 2,6,9, Idris Guessous 1

Geneva, Switzerland

  

Discussion

The preliminary results of this study provide an important benchmark to assess the state of the

epidemic. With an estimated 48’500 people having developed antibodies (9.7% of 500’000

inhabitants) while 4741 cases were confirmed on April 24th 5, we observe that there are roughly 10

infections for every COVID-19 confirmed case in Geneva, reflecting the variability in disease severity,

testing practices and care-seeking behaviors. Further, we show that three weeks after the peak of

confirmed cases, only 1 in 10 people has developed antibodies against SARS-CoV-2, even in one of

the more heavily affected areas in Europe 13. Thus, assuming that the presence of IgG antibodies

measured in this study is at least in the short-term associated with immunity, these results highlight

that the epidemic is far from burning out simply due to herd immunity. Given the time to development

of IgG antibodies (1-3 weeks), we expect to continue seeing significant increases in seroprevalence

over the coming weeks 14.

We found no differences in seroprevalence between children/young-adults (5-19 years old) and middle

age adults, with those older than 50 years having a significantly lower seroprevalence than 20-49 year

olds. Although children present typical COVID-19 symptoms far less frequently than adults, these

results provide support to emerging research showing that they indeed get infected at similar rates 15.

This should be considered in view of increased concerns about severe inflammatory syndromes in

children that could be COVID-19-related 16, and of the worldwide debate around opportunity and

modality of school re-openings. While the sample size of older adults was small, the lower

seroprevalence estimates in this group suggest that targeted efforts to reduce social mixing of elderly

people with others may have succeeded. However, it remains possible that, because of an age-related

compromised ability to generate adaptive immune responses, the elderly develop a lower IgG response

after infection, something that needs further investigation

Update 3

Similar over prevalence finding in Spain at El Pais English edition

Antibody study shows just 5% of Spaniards have contracted the coronavirusPreliminary findings of the survey reveal that over 90% of infections have gone undetected by the healthcare system
Madrid - 14 MAY 2020 - 15:32 CEST
Only 5% of Spaniards have been infected with the coronavirus, according to the preliminary results of a study by the Carlos III public health institute, which took blood samples from nearly 70,000 participants.
The prevalence study was conducted to determine how many people in Spain have developed antibodies after exposure to the virus. Similar studies in other countries are being used to help make decisions about easing confinement measures....