World / Science & Health

Studies begin to lift veil on new coronavirus

AFP-JIJI

Just three months ago, few people were familiar with the word “coronavirus.” But as the disease continues to spread across the globe, infecting and killing thousands while causing millions to live in self-isolation, it has entered daily use for billions.

Here are some of the questions that have been raised since the new coronavirus that causes COVID-19 became headline news around the world:

Who is most at risk?

The severity of COVID-19, the disease caused by the virus, increases with age, according to various studies.

The latest edition of the British medical journal The Lancet, published on March 31, shows that the disease is on average much more dangerous for those over 60, with a mortality rate of 6.4 percent (among confirmed cases).

The mortality rate climbs to 13.4 percent for the over 80s against just 0.32 percent of deaths for the under 60s, according to studies made mainly on several hundred Chinese cases observed in February.

Similarly, the study shows that the proportion of patients requiring hospitalization increases sharply with age: 0.04 percent for 10 to 19-year-olds, 4.3 percent for 40 to 49-year-olds, 11.8 percent for 60 to 69, and 18.4 percent for those over 80.

The last of these figures means that about one in five octogenarians develops a form serious enough to require hospitalization.

Besides age, having a chronic illness — for example, respiratory failure, heart disease, a history of strokes or cancer — is also a risk factor.

In a recent report on 10,000 deaths, the Italian Higher Institute of Health (ISS) identified common existing illnesses in the deceased.

The most common were hypertension (73.5 percent of cases), diabetes (31 percent) and coronary heart disease (27 percent).

Finally, according to an extensive analysis published on Feb. 24 by Chinese researchers in the American medical journal JAMA, the disease was mild in 80.9 percent of cases, “serious” in 13.8 percent of cases and “critical” in 4.7 percent of cases.

How many deaths can we expect?

The statistical correlation between the number of deaths in the world and the total number of officially registered cases suggests COVID-19 kills approximately five percent of diagnosed patients, with disparities according to different countries.

That fatality rate has to be treated with caution as it is still unclear how many people have actually been infected.

Since many patients seem to develop few or no symptoms, their number is likely to be greater than the cases detected, which would lower the rate.

In addition, countries have very different testing policies and some do not systematically test all suspected cases.

A few weeks ago, Anthony Fauci, director of the National Institute of Infectious Diseases in the U.S., told Congress that the fatality rate was much lower than five percent.

“If you count all the cases of minimally symptomatic or asymptomatic infections, that probably brings the mortality rates down to somewhere around one percent,” he said, adding that this still makes the new coronavirus “10 times more lethal than the seasonal flu”.

The study published in The Lancet on March 31 estimated the proportion of deaths among the confirmed cases at 1.38 percent.

However, the danger of a disease depends not only on the overall death rate but also its ability to spread.

Even if only one percent of patients die, “it can make significant figures if 30 percent or 60 percent of a population is infected,” said Simon Cauchemez of the Pasteur Institute in Paris.

The other factor that is affecting fatality is congestion of hospitals, caused by a sudden and a massive influx of cases.

This complicates matters not only for those patients with severe forms of COVID-19 but for everyone else as well.

What are the symptoms?

According to the World Health Organization (WHO), the most common symptoms “include respiratory problems, fever, cough, shortness of breath and difficulty breathing”.

Each of these symptoms may be present to a greater or lesser extent depending on the case, and the development of symptoms fluctuates.

Another common symptom is loss of smell and taste.

According to a recent Belgian study carried out on 417 patients who were “non-severely” infected, 86 percent had problems with smell — most of them no longer sensing anything — and 88 percent had taste disorders.

Symptoms usually lasted two weeks or more, sometimes less. For some people, they get worse.

“In the most severe cases, the infection can lead to pneumonia, severe acute respiratory syndrome, kidney failure, and even death,” the WHO has said.

There is no vaccine or medication, so managing the virus involves treating the symptoms. However, some patients are administered antiviral drugs or other experimental treatments, the effectiveness of which is still being evaluated.

How is it transmitted?

The virus is mainly transmitted by respiratory routes and by physical contact.

Transmission occurs in the droplets of saliva expelled by a patient, for example when he coughs. Scientists estimate that this requires a close contact distance, of about one meter (3.3 feet).

To avoid contagion, health authorities emphasize the need to take precautions. These include washing hands frequently, coughing or sneezing in the crook of one’s elbow or in a disposable handkerchief, and avoiding shaking hands and kissing.

They recommend wearing a mask if you are sick, and point out that you can become infected by touching a contaminated object and then putting your hand to your face — eyes, nose or mouth.

A study published in mid-March in the American journal NEJM showed that the new coronavirus is detectable for up to two to three days on plastic or stainless steel surfaces, and up to 24 hours on cardboard.

However, these maximum durations are only theoretical, since they are recorded under experimental conditions.

“It only takes a little bit of the virus to remain on a surface to infect someone who touches it,” warned French health authorities on their official website.

“Indeed, after a few hours, the vast majority of the virus dies and is probably no longer contagious.”

Another unknown is whether the virus can be transmitted simply through breath rather than coughing or sneezing. This has been the subject of much speculation in recent weeks but nothing has yet been scientifically proven.

Can a person be infected twice?

Is it possible to be contaminated by the new coronavirus, to recover and test negative, only to contract the virus a second time? Several cases in Asia have raised this question.

Given the extent to which these cases were isolated, scientists believe the patients probably never fully recovered in the first place.

The negative test can either come from the fact that it was not done properly or because at that point the presence of the virus in the body was very weak.

However, there is still no certainty about the level of immunity we can acquire against the new coronavirus. Based on the example of other viral diseases, specialists believe that once cured, a person is temporarily immune, even if this is not yet proven.

Crucially, however, it is not known how long this supposed immunity lasts.

“If, theoretically, a person can maintain immunity for a prolonged period (for instance 12-24 months) post-recovery, they could conceivably safely return to public spaces even as the virus continues to circulate,” says the Center for Strategic and International Studies (CSIS) in Washington.

“Inversely, if immunity is very short-lived, a person who has been infected could soon become reinfected.”

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