Two months after its appearance in China, the new coronavirus continues to spread throughout the world and it could spread to countries other than the 30 currently concerned, and especially for a long time.
Appeared in December in Wuhan, China, the Covid-19, the novel coronavirus which has adapted to humans, is very contagious. To date, it has caused more than 72,000 identified infections, figures probably underestimated due to the number of cases with no or few symptoms, and nearly 1,800 deaths, figures which are changing day by day despite strict quarantine. .
This new coronavirus is probably derived from a bat coronavirus, which would give it a particular ability to be little attacked by the human immune system. Its current animal reservoir is not yet known, which further complicates the exact understanding of its kinetics.
We now know that it is resistant to cold and humidity and that it can persist for several days on different materials and surfaces under these circumstances. We do not yet know its behavior in the event of heat and drought, but we hope that it does not support them well, like the other coronaviruses.
The incubation period is most likely less than 2 weeks, which validates the current quarantine duration, but the problem is that asymptomatic (and non-febrile) or mildly symptomatic patients (with a simple “cold”) can be contaminating.
The mode of contamination is most often respiratory (cough, sneeze, Pflüge droplets), and hand-carried, especially since it could be found in the stools of some patients. At this stage, 3 questions still arise.
Will the epidemic continue to spread?
Covid-19 to all qualities to cause an epidemic on a world scale, i.e. a pandemic. According to some scientists, he also has everything for this epidemic to be persistent or recurrent. This new virus is, indeed, highly contagious, arguably almost as contagious as the flu virus according to many infectious disease experts. We are at more than 71,000 official cases, that is to say infected patients and severe acute respiratory infections, but not all asymptomatic patients are identified (“the tip of the iceberg”) and more than 3,000 healthcare professionals were infected (5 deaths).
This implies that, despite the drastic measures put in place in China, the epidemic is only slowing down. It was this dissemination profile announced by Professor Anthony Fauci, director of the National Institute of Allergy and Infectious Disease (United States), who had been interviewed by the New York Times. He had announced that with such a degree of contagiousness and with many healthy carriers, quarantines could not be 100% effective.
Proof if any, the United States evacuate their nationals from the cruise ship, the Diamond Princess, while 99 new cases have been detected on this ship. Placed in quarantine with 3,711 people on board from the beginning of February in the port of Yokohama due to a patient, the passengers having the order to stay in their cabin and not to meet, there are now 454 people who have been contaminated despite these measures and the evacuation of the sick as and when. Fourteen Americans among the 300 evacuees would also be positive for the new virus according to The world. To leave the passengers on board is therefore to condemn them all to becoming ill.
How is the virus transmitted so easily among passengers isolated in their cabins? This is because they become contaminated, either through objects touched by asymptomatic patients (door handles, etc.), or through asymptomatic staff members who cook or bring them supplies, or by air conditioning and this was observed with SARS during the 2003 epidemic in Hong Kong (Hotel Metropole) and in Foshan, near Canton.
How long will all of this last?
The increasingly strict quarantine measures put in place in China seem to be slowing the spread of the virus, but it is not certain that with such a high degree of contagiousness the epidemic can be stopped at this stage. Various information from China and a study in Germany, published in the New England Journal of Medicineindicate that some people infected with the new coronavirus can transmit it before they themselves have the slightest symptoms.
This therefore makes border control even more difficult and the actual number of asymptomatic patients missed by thermal imaging cameras could be more than 75%, experts say. Over the days, the number of cases abroad is increasing very gradually (nearly 900 currently) and, with an average contamination of 2.5 cases per infected person and a doubling time 6.5 days out of quarantine, that’s almost 60% of the world’s population who could be infected (at most).
Fortunately, the death rate seems to be around 2% of infected patients, which is still confirmed in a study Chinese epidemiology on the first 44,000 cases, which is much less than SARS (about 10%) and MERS (30%). The disease is moderate in more than 80% of cases, severe in almost 15% of cases and critical in 5% of cases.
The deaths would mainly concern the oldest and sickest people (cardiopathy, diabetes, respiratory failure, etc.). But what this coronavirus has lost in lethality, it would have gained in contagiousness, which can lead to a significant total number of deaths if nothing is done to control the spread: a rate of 2% applied to a very contagious and having affected many people, this is what happened in 1918-1919 with the “Spanish flu”. While usually the flu gives mortality rates of around 0.1%, but in those years, due to the high mutation of the flu virus, the mortality reached 2%, which mathematically resulted in tens millions of deaths (between 30 and 50 million).
What to expect in Western countries?
The flu gets better in the spring and summer, with the heat, and that’s also what seems to happen with the other mild coronaviruses, as well as SARS and probably MERS. So we can hope that, thanks to the titanic efforts of the Chinese, the virus will not arrive en masse in Europe and the United States in the next few months, leaving the climate to protect us until the fall.
But the lockdown in China’s economy cannot last forever, Chinese people are returning from the Chinese New Year holiday, and even with precautions, the restarting of factories, transport and basic economic life carries the seeds of a new outbreak of the epidemic. In the event that the infection improves in summer, Covid-19 can also cause a new epidemic in October-November 2020, or even settle for several years in the world.
The evolution is, at this stage, “impossible to predict” according to the WHO but, with the quarantine, the spread of this coronavirus in the world could take place in several years instead of several months. This delay is welcome because the effective means of controlling the epidemic and treating the sick, which we have deployed in our countries, may work for a few patients, but what will happen if it is thousands or millions?
Fortunately, some therapeutic avenues seem to be emerging, with effective drugs or combinations of drugs (antiretrovirals, anti-JAK or anti-coronavirus) that are promising but are being tested in China, which represents hope for controlling the disease. disease. Research on vaccines has been launched by several teams around the world, thanks to the sequencing of the virus and its cultivation, but nothing should be available before 2021, especially on a large scale. So any delay is good to take.
In the meantime, China, “the factory of the world” is idling and will impact economic activity at all levels (spare parts, drugs, finished products, etc.). Japan, one of the countries with the most cases outside China and where more and more infections are appearing in people who have not been to China and who have not met people from of China, is likely to be reached fairly quickly. Above all, we do not have valid data on many countries where the virus can develop and where healthcare infrastructures will be quickly overwhelmed. The first case in Africa was reported in Egypt and there is enough to hold one’s breath vis-à-vis the rest of Africa and the Middle East. What will happen, for example, if the virus arrives in Syria?
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