What we know and don't know about the COVID-19 coronavirus

The new coronavirus (in blue) arises from cells grown in  laboratory. Virus obtained from an American patient.
The new coronavirus (in blue) arises from cells grown in laboratory. Virus obtained from an American patient. Copyright National Institutes of Health/ AFP
Copyright National Institutes of Health/ AFP
By Rafael CerecedaEuronews
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What we know and don't know about the COVID-19 coronavirus


One of the difficulties in fighting the pandemic that has turned the world upside down is that science knows little about the coronavirus responsible for COVID-19 — or SARS-CoV2 — that caused it.

To debunk fake news circulating about the virus, and make a point about the current scientific knowledge of the virus Euronews interviewed Morgan Gaia, a researcher on the co-evolution of viruses and cells at the French public research group CEA.

SARS-CoV2's family of viruses is not unknown to science, but the specific characteristics of human diseases associated with this SARS-CoV2 strain (such as incubation time) have yet to be studied in full, Gaia said.

Furthermore, the various lifestyles, climates and government measures in countries affected by the virus are all parameters that affect the data scientists have, he explained.

Knowledge of the virus grows every day, but the recent avalanche of preliminary scientific publications on COVID-19 has confused the press and the public even more.

This is the case of chloroquine, which despite not being a clinically proven cure is already sold out in pharmacies across the world. Another highly criticised study has suggested that fine particle contamination could be a vehicle for the spread of the virus.

Euronews takes a look at what we know for sure, and what remains unknown about the novel COVID-19 coronavirus.

What do we know about the new SARS-CoV-2 coronavirus?

According to Morgan Gaïa, many of the characteristics are common to other known viruses, but a combination of factors are different.

Easy contagion

The novel COVID-19 coronavirus spreads easily and exponentially. "It is estimated that, without containment measures, an infected person will infect an average of 2 or 3 people", Gaïa explained.

"There are also documented cases of 'super contaminators', that is, infected people who, for reasons that are not well understood, contaminate a higher number of people. This is facilitated by the lack of immunity of the population, as it is a new virus."

Scientists point out that the coronavirus spreads quickly because it is practically "invisible": in many cases, around 50% and potentially more, it does not cause symptoms or only mild symptoms, similar to a flu or a common cold.

Gaïa pointed out that "although these cases may be approximately 50% less contagious than those with more advanced symptoms, their large number would be an important contributor to the spread."

Lack of preparation in many countries

Many countries' lack of preparation in the face of a pandemic, combined to the slow reaction of the authorities and citizens, has led to the current situation, with a third of humanity in lockdown to slow the spread of the virus.

"In Asia, they are better prepared because they have had other epidemics and they are more disciplined when it comes to protecting themselves and applying isolation measures," Gaïa said.

Epidemics always have a political component. Authorities often hesitate to apply unpopular measures, which can cause panic and potentially harm the economy. Such hesitation, from China to the United States and Europe, was also key to the current situation.

Globalisation greatly facilitated the virus' spread. The fact that it has appeared in a city of 11 million inhabitants, hyperconnected by land, sea and air — and in China, a country considered to be the "factory of the world" — has favoured this unprecedented situation.


Ignorance about the virus

Another problem has been the lack of knowledge and communication between scientists, authorities and the public.

There are doubts about the Chinese scientific community's adaptation to international scientific standards as well as about the influence of Chinese authorities in their publications.

"A lot of the research has only been published in Chinese," Gaïa said, "often without clear statistical figures."

The flagging of symptoms such as fever and cough in the early stages of the epidemic as signs to isolate the sick was also a misstep, as it ignored the fact that carriers could show no symptoms or mild symptoms. This, in turn, slowed the authorities' capacity to slow the spread of the virus.


It was not created in a laboratory

The researcher flatly rejected conspiracy theories about a "laboratory-created" virus, adding that viruses play a regulatory role in nature, and that although COVID-19 has taken most governments across the world by surprise, it was to be expected that at some point a similar pandemic would occur.

"The factual analyses unambiguously confirm that this is a naturally occurring virus," Gaia said.

He pointed to the loss of biodiversity and our impact on the environment as one of the triggers.

"When we reduce the distance between the natural world and the human world, when we leave so little space for wild animal and plant species, we encourage viruses that are natural to other species to be transferred as human beings and situations like this," the researcher said.


Very diverse effects on the human body

We also know that the virus is capable of causing acute respiratory syndrome and even death. 

And it does not only affect the elderly. In France, an estimated 50% of intensive care patients are under the age of 60. While it remains an exception, a 12-year-old girl in Belgium and a 13-year old boy in the UK infected with the novel coronavirus have recently died.

When infection occurs, it is capable of creating, in addition to pneumonia, a chain reaction that can affect most organs. The body's immune response is often so violent that it can damage healthy tissue.

It is increasingly believed that severe to deadly cases of COVID-19 are caused by an overreaction of the immune system - a cytokine storm - rather than the viral load itself, but more research is needed.


The disease affects children very little. They develop fewer symptoms and there are very few cases of minors affected by severe forms of the virus.

Yet children can carry the disease, which is why one of the first measures worldwide was closing schools.

The new coronavirus is known to invade cells thanks to its ability to "hack" the cell's ACE2 receptor.

Risk factors

Age is the determining factor in developing severe symptoms that can threaten the patient's life.


Most of the serious and deceased cases are men. It also seems to be proven that patients with hypertension, diabetes and cardiovascular and chronic respiratory diseases are more likely to suffer complications from COVID-19.

Blood groups have also been studied and the blood group A seems to be more vulnerable.

What we don't know about the new COVID-19 coronavirus

Despite the tsunami of information to which we are exposed every day, we still know very little about the new virus.

The real figures of confirmed cases and death tolls

Most countries, with few exceptions, are currently very limited when it comes to testing.


There are also differences in the way they account for cases and deaths.

For example, in France only deaths in hospitals are counted: therefore, cases of contagion or deaths at home or in nursing homes remain unreported.

Morgan Gaïa points out that "some countries also lack the resources to centralise their data, while others may lack transparency."

Lack of evidence

The fact that many political and cultural personalities have announced that they have COVID-19 highlights the fact that they have easier access to tests, even with mild or no symptoms. The limited capacity to carry out tests makes it impossible to know the real numbers of the pandemic today.


More accurate estimates could only be made with serological analyses, which would show the proportion of the population that already has SARS-CoV-2 antibodies.

According to Gaïa, the capacity and reliability of the tests "are also affected by the stage of infection in a patient and the source of the sample" (nose, throat).

"It will not be possible to test all of humanity at any given time", Gaia added. "We can only have estimates and simulations."

The proportion of asymptomatic cases

Initially ignored, more and more studies suggest that the high proportion of undocumented cases (without symptoms or with mild symptoms) has favoured the spread of the pandemic. The WHO estimates that 80% of people will experience mild symptoms.


Everything indicates, then, that the actual numbers of contagion are much higher than the official ones. And therefore, the real mortality rate of the virus is much lower.

How long are patients infected

The length of the quarantine, 14 days, is an approximation. It is not known for how long a patient is contagious.

Sick or not, everyone is a potential carrier of the virus. Hence the importance of generalised lockdown and social distancing measures.

Chinese studies have shown that the virus can be detected in patients (and therefore potentially transmitted) for 8 to 37 days, with an average of 20 days.


The contagion

It is not known exactly how long the virus can survive on different surfaces.

We also don't know for sure whether the virus is transmitted only by saliva droplets in the air (such as when someone sneezes) or also by the breath of an infected person.

"We know that the main routes of entry are saliva, nasal excretions like cough and sneezing, and hand contact with a contaminated surface", Gaïa said.

He added that contamination through air is for now "hypothetical".


It has been estimated that the virus can stay up to 2 or 3 days on plastic and steel, 24 hours on cardboard, potentially up to 3 hours in the air - but only in laboratory conditions. Outside, the virus' survival depends on environmental conditions. Humidity and cold are believed to help it survive.

Hand washing and avoiding crowds are still the most effective barriers against it.

The immunity of those who have carried the disease

Chickenpox immunity lasts a lifetime, but immunity to colds caused by other types of coronaviruses is very short, so people can catch them even several times in the same winter.

Every season, it is necessary to develop new vaccines. It is not known how long the SARS2 immunity lasts.


COVID-19's exact origin

The latest research seems to confirm that the virus is of animal origin. It probably came from bats and was transmitted to humans by the pangolin, but so far there is no certainty.

Scientists think it is a combination of viruses.

"It is a natural phenomenon", Gaia explained. "Viruses circulate in a population that acts as 'reservoir species' (in the case of coronaviruses, often bats, which are very resistant) and then it is transmitted to an intermediate species in which it adapts, before being transmitted to humans."

Treatment and vaccines


There is no proven effective treatment.

There is much talk of chloroquine, but nothing has been confirmed.

Laboratories around the world are working on clinical trials to find a vaccine, which could take more than a year to be developed and distributed.


Although summer and heat are expected to slow the pandemic in the northern hemisphere, based on available data on other viruses, it is not known whether it will spread in successive waves, as the Spanish flu did, for example.

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