To date, the SARS-CoV-2 coronavirus epidemic has claimed more than 1,900 lives since its emergence. The number of infections in mainland China increased on Tuesday, February 18, to 72,300, while elsewhere in the world about 900 infected people have been identified in around thirty countries and territories. The World Health Organization (WHO) was however reassuring Monday: outside of the Chinese province of Hubei, epicenter of the epidemic, the disease, known as Covid-19, “Affects a very small proportion of the population” and her death rate is currently only around 2%, she said. Arnaud Fontanet, head of the epidemiology unit for emerging diseases at the Institut Pasteur and professor at the National Conservatory of Arts and Crafts, answered your questions about the coronavirus and the disease it causes.
What do we know about the incubation period of the coronavirus and its contagiousness?
Arnaud Fontanet: current estimates of the average length of the incubation period converge to six days, with a maximum duration of twelve days. The period of contagiousness begins with the symptoms, and even, in some cases, before the first signs.
What are the warning signs of SARS-CoV-2 contamination?
First you need to know if there has been a trip to an epidemic area or contact with an infected person in the previous 14 days. Then, the symptoms are: fever, general malaise, muscle pain, dry cough and possibly respiratory discomfort. Throat pain, runny nose or diarrhea are rarely found (5 to 10% of cases).
How to tell the difference with a strong flu?
There are no notable differences between the severe forms of Covid-19 and a severe flu, and, as with the flu, there are frequently mild forms.
Does coronavirus mainly kill the elderly or those with weak immune systems?
A recent publication by the Chinese Center for Disease Control and Prevention (CDC) out of 45,000 confirmed cases reports that 80% of deaths occur in people over 60, most often with associated diseases such as diabetes or hypertension arterial (HTA). There are a few deaths among young and healthy subjects, as seen with other respiratory viruses such as SARS (severe acute respiratory syndrome) or pandemic influenza from 2009-2010 [A (H1N1)].
Is the coronavirus mortality rate underestimated?
It is currently at 2%, which is probably an overestimate. Admittedly, there is a delay in counting deaths, because the time between the appearance of signs and death, in the event of an unfavorable development, is two to three weeks, but we do not know the real number of people infected. Indeed, a significant part of the forms is benign, even asymptomatic, and does not lead patients to consult a doctor.
The number of deaths must therefore be related to an even greater number of cases of infection and the fatality rate would therefore be less than 2%. It will be possible to better estimate the number of people infected when we have serological tests (which detect the presence of antibodies in the blood indicating that there has been an infection by the coronavirus).
Why does coronavirus disease seemingly claim fewer lives in infants?
Generally, children and infants have mild forms of the disease. Even when the CT scan reveals images of blunt pneumonia, children seem to tolerate the disease better. It could be a more suitable immune response. This has been observed for other childhood viral diseases.
Are people vaccinated against influenza better protected against SARS-CoV-2?
No. But, in addition to the fact that vaccination protects against the flu and reduces the burden on the health system, knowing that someone has been vaccinated against the flu further directs the diagnosis to another cause.
What do trials of antivirals give for curative treatment?
A trial using the combination lopinavir-ritonavir was conducted in China. We await the results. Other trials are underway or planned with various molecules: interferon beta, remdesivir, chloroquine. Plasma transfusions from recovered patients and therefore containing antibodies to SARS-CoV-2 are also being considered.
Is it possible to develop a vaccine in a short time?
Many teams around the world work there. It takes eighteen months to hope to have a vaccine that has been shown to be tolerable and effective and that large-scale production could start.
When can we expect an end to the Covid-19 epidemic?
There appears to be a slowdown in the epidemic in China’s Hubei province. Nevertheless, we fear the appearance and development of epidemic foci in other provinces or outside of China which could take over. However, they are not expected to be as active as the one from Wuhan.
Can the coronavirus survive summer temperatures?
It is true that cold-associated coronaviruses are seasonal, but this is largely due to the fact that people live in more confined spaces during the winter. The MERS-Coronavirus is spread throughout the year in the Gulf countries. It is therefore too early to conclude on the impact of temperature variations on the course of the epidemic.
Should we avoid gatherings, air travel, cruises, to avoid contamination?
It depends on the epidemic situation in the place where you live. In France, there is currently no reason to worry. On the other hand, conventional measures to prevent respiratory infections, such as the flu that is currently circulating – coughing in your elbow, disposable handkerchiefs, hand hygiene, etc. – are recommended.
Why worry about this coronavirus when the seasonal flu has already claimed many more lives?
Even though the Covid-19 epidemic has resulted in fewer deaths than seasonal flu, the fact that it is a new virus is causing a lot of legitimate concern, but also disproportionate reactions that can have a societal impact, considerable political and economic. China is an example. It is therefore important to talk about it and inform it so that the response to the epidemic is well adapted.
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