“There is no evidence that there is an absence of immunity in cured patients” – News from the web

A caregiver takes a sample to test for a patient potentially carrying SARS-CoV-2 at a hospital in Coslada, Spain, on April 20. Manu Fernandez / AP

What are the advances in research into treatments for Covid-19? Where is the development of a vaccine? Paul Benkimoun, journalist specializing in health issues at World, responded to our readers during our live, April 20.

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Marti: Can we be naturally immunized against the coronavirus?

The only way to get immunized, as long as there is no SARS-CoV-2 vaccine, is to get the disease, as is the case with other infections.

Florian: How long does it take to recover from the disease in its mild forms?

In mild forms, the symptoms disappear within a few days, sometimes more (a week), especially if the fatigue has been severe. Some often-present signs, such as loss of smell or taste, take a little longer to disappear.

Zenga89: According to the WHO, “it is not established that the presence in the blood of antibodies to the coronavirus protects from a new infection”. Would this phenomenon, if confirmed, jeopardize the hope of a vaccine?

We do not yet have evidence that the antibodies produced as a result of SARS-CoV-2 infection are able to neutralize it in the body. The question can only be decided once there is sufficient scientific data to establish whether or not there is protection from these antibodies.

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Antibodies are not our only immune defense. In addition to this so-called “humoral” response, which relies on antibodies, we also have a “cellular” response which passes through a category of specialized white blood cells: CD8 T lymphocytes. The development of a vaccine capable of inducing both an antibody response and a cellular response would resolve the problem of antibodies that are not effective enough against SARS-CoV-2.

Paul: What about announcements about the healed sickness of Covid-19 immunity?

It has not been shown that there is an absence of immunity in cured patients. The uncertainties relate to the fact of knowing if it is really reinfection (infection, followed by a cure, then a second infection), a problem which would be linked to the tests (false negative test in a person “Cured”, then a new positive test) or an apparent disappearance of the virus which could remain in the body, in what is called a reservoir. Again, the accumulation of data will help get out of uncertainty.

The Defense Plaza, April 20.
The Defense Plaza, April 20. Michel Euler / AP

Marie: It seems that post-Covid immunity is not certain, which is bad news … Shouldn’t we, then, see a resurgence of cases in China?

The risk of resurgence is linked to the maintenance or not of measures of social distancing (to keep at a distance, wear a mask…) and a policy of detection and isolation of cases of infection, identification of people in contact and their isolation, which is based on the use of diagnostic tests. China maintains such measures. Other countries do the same.

Mistrustful: I just received information that seems to be viral about the role of an intestinal bacteria, the Prevotella… Is this track reliable?

If there is still a lack of knowledge about the new coronavirus, it is firmly established that it is the agent that causes Covid-19. Does this infection cause changes in the intestinal bacterial flora, including Prevotella is part of it? This has not been established and does not appear to be a determining factor in the Covid-19.

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Koikilenkoute: To my knowledge, only one diagnostic test is 99% reliable, it is the pulmonary scanner. Why is it never mentioned in government communications?

If it is preferable a priori to have a diagnostic certainty, it is necessary to measure the quality of medical information in the light of practical aspects. A lung scanner can diagnose lesions in the lungs, but the first information sought is whether a person is infected with SARS-CoV-2. A strong presumption may exist on the basis of clinical signs (fever, fatigue, cough, but also loss of smell, taste …) and the notion of contact with an infected person. A PCR test after sampling from the nose will identify SARS-CoV-2. The scanner has no relevance for the mild forms which represent the vast majority of infections with this new coronavirus.

Bibi: I still do not understand that the President of the Republic could have said that systematic screening had “no sense”. In the face of an invisible enemy, isn’t the first answer to try to locate it, and therefore to practice large-scale tests to detect asymptomatic carriers?

The president and the executive have not chosen to explain the limitations on the ability to test massively, and to recognize that the strategy has adapted to these limitations. The speech justified the choice not to systematically test otherwise. The same was true for masks. However, one must take into account a logic of feasibility. Systematically testing people in contact with a case, even if they have no symptoms, is essential. Yes “Test the asymptomatic” means testing the entire population, this is impractical, since these tests will also have to be repeated.

An anti-containment protester, dressed in the iconic costume from the series
An anti-containment protester, dressed in the iconic costume from the series “The Scarlet Handmaid”, in Denver, Colorado, on April 19. JASON CONNOLLY / AFP

Chab12: What are the reasonable times to expect a vaccine?

Over a hundred vaccine trials have started worldwide, as an article on our site specifies today. Getting started means starting a long process, consisting of several steps to ensure the safety of the vaccine candidate, then the fact that it elicits an immune response and then that this immune response protects well against infection.

It is impossible, unless taking unacceptable risks, to skip these steps first on animal models and then in humans, before launching large-scale production – because it will require one or more vaccines accessible worldwide – and proceed with the vaccination. Some manufacturers use a technique with messenger RNA, which shortens the time, usually around eighteen months, but it seems very unlikely to have a ready-to-use vaccine on a large scale before 2021 .

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CD: It was said a few weeks ago that certain forms of the disease mainly affect the digestive system, causing diarrhea in particular. Is this symptom associated with the most common symptoms (fever and cough), and are these forms of the disease mild or severe?

This sign has been described in Chinese publications and has also been found outside of China. It is not the most common symptom and has not been shown to be a sign of any particular severity.

Suzanne: Are pregnant women considered to be at risk who are likely to remain confined? A teacher and five-month pregnant, I wonder if it will be prudent to resume classes in May.

Yes, a pregnant woman is considered to be at risk since Covid-19 has not been shown to be safe for her and the unborn child. This therefore implies more restrictive measures than for another person.

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Very calm and healed: We hear about tests with the BCG vaccine against the coronavirus. If this vaccine is effective, why should the population already vaccinated (which I imagine to be large) not already be protected?

The use of BCG to stimulate the immune response is the subject of a study in France. Having been vaccinated, sometimes a long time ago, which is the case for older people at higher risk of developing a serious form, is apparently not enough to provide protection. As has been done in other diseases, it is a question of giving new stimulation to the immune system.

Julie: Do we have any information regarding the genetic stability of the virus? Does it mutate quickly?

At this stage, there have been no scientific publications reporting significant mutations in the virus that could alter the consequences of the infection.

Questioner: What about Professor Raoult’s protocol?

The publications aiming to make this protocol effective have serious shortcomings which do not allow conclusions to be drawn. Publications, not all of good quality, go in the opposite direction and do not find any efficacy of the hydroxychloroquine-azithromycin combination. More reliable results will come with larger, state-of-the-art studies.

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A municipal worker disinfects the area around a kindergarten in Madrid on April 20. Children under the age of 12 may be allowed to go out to Spain again on an ad hoc basis from next week.
A municipal worker disinfects the area around a kindergarten in Madrid on April 20. Children under the age of 12 may be allowed to go out to Spain again on an ad hoc basis from next week. Paul White / AP

False negative: Do we have more details on the percentage of false negative virological tests and therefore on the reliability of these tests when they will be an important element of deconfinement?

Some tests have questionable reliability, their sensitivity could drop as low as 30%, but other serological tests are being developed, among others by the Institut Pasteur, which should be much more reliable.

Soloforak: The President of Madagascar announced yesterday the discovery and distribution of a plant-based preventive and curative medicine, artemisia. What credibility should be given to this treatment?

This is indeed the announcement that was made by the Madagascan president. The use of herbal teas based on artemisia is promoted by some against malaria because the most recent treatments are derived from this plant, but this is far from being unanimous among scientists. The relevance of its use as a treatment for Covid-19 is far from having been established.

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Thierry: Is there international cooperation between laboratories or is it a race for the first to find?

It is precisely to avoid this every man for himself and a jackpot for those who would develop a vaccine that governments and international bodies, starting with the WHO, must already impose that treatments, vaccines and diagnostic tests are available worldwide, which excludes prohibitive prices.

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Source: International: All the news on Le Monde.fr.

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