Half of the people who test positive for Covid-19 would have no symptoms. Their immune systems could develop antibodies that fight infections. They are infected but are ‘healthy carriers’. How long are they contagious? Are they immune?
[Mis à jour le vendredi 4 décembre à 15h39] Of all tested from November 27 to December 3, 2020, 72% stated that they were symptom-free, a figure identical to that of the previous week. And half (50%) of the positive cases showed no symptoms, according to the Public Health France epidemiological point of Dec.3. Otherwise, half of the transmissions take place during the pre-symptomatic phase of the patient before symptoms appear. This means that one can be contagious even without symptoms. But exactly, What does “being a healthy carrier” mean? ? Is this the same as an ‘asymptomatic’ ? How do you know if you are a healthy carrier of a virus? While how long have we been contagious ? What is the typical profile of a healthy Covid-19 carrier ?
A healthy carrier is a person whose body has been infected with an infectious agent (virus, bacteria, parasite) but which does not show clinical symptoms of this infection. In other words, he carries the infectious agent in his system without being sick. In contrast, a healthy carrier can transfer the infectious agent to other people with whom they come into contact. A healthy carrier is therefore contagious.
To diagnose an asymptomatic person with Covid-19, we cannot rely on the presence of symptoms. The only way to know if you are a carrier of Covid-19 (with or without symptoms) is to test for the presence of the virus, thanks to the realization ofa PCR test (a sample of the nose with a cotton swab) to determine possible contamination with Covid-19. If a person is infected with the coronavirus at the time of the sample, the PCR test will detect it.
- If the test is negative, we infer that the person is not a carrier of the virus
- If the test is positivewe conclude that the person is a carrier of the virus and is therefore contagious.
• If the positive person has no symptoms at the time of the sample, it would be a healthy carrier.
• If the positive person has symptoms (fever, cough, loss of smell, etc.), then it is symptomatic, it is not a healthy carrier.
► Attention: there are “false negatives“which may be due to poor sampling technique.
► Insulation for how long? With or without symptoms, a person who tests positive for Covid-19 should stay isolated for 7 days after taking his test.
The healthy carrier has no symptoms yet remains contagious. It can therefore transmit the disease to other people. “In the case of Covid-19 this is especially true for children, adolescents or young adultsFrédéric Tangy, retired CNRS researcher, now assigned to the Institut Pasteur’s vaccine innovation laboratory in a Sud-Ouest article. With or without symptoms, a person infected with Covid-19 can transmit the pathogen. 3 people on average, the World Health Organization recalls.
A healthy carrier would be less contagious compared to a person with symptoms.
The incubation period of Covid-19, i.e. the time that elapses between the moment of infection and the appearance of symptoms of a disease, is 3 to 5 days in most cases, it can be up to 14 days. This means that an infected person can transmit the disease up to 3 to 14 days before symptoms appear (the average is estimated at 1 week). But since an individual can be a ‘healthy carrier’, there is always a risk of contaminationeven after the incubation period. If not isolated, this person can unknowingly transmit the virus to others who in turn can develop a clinical, sometimes severe form of the disease. Asked by the 7:45 pm broadcast on M6, Prof. Yves Buisson, epidemiologist and chair of the National Academy of Medicine’s Covid-19 group, indicates thatisolation makes it possible to imagine that a healthy carrier is no longer contagious. However, to get out of this isolation, the healthy carrier must take two negative samples to verify the absence of the virus.
However, a healthy carrier would be less contagious compared to someone with symptoms. because he doesn’t cough and sneeze. “We’ve wondered a lot if we could be contagious by being asymptomatic. Which is ultimately unlikely. Because to be contagious you still have to excrete drops, that is, cough, sneeze. And so someone who certainly has no symptoms could be a carrier – it is very likely and we find them with extremely few symptomatic forms from time to time – but eventually has few resources to spread the virus”says Jérôme Salomon, Director General for Health.
Nothing proves it. Nevertheless, an initial infection with Covid-19 would lead to a form of protection faced with the virus in the vast majority of cases, even if about fifteen cases of reinfection have been reported worldwide, particularly in Hong Kong, the Netherlands, the United States and Belgium. Theoretically, it would therefore be possible to get infected with the corona virus several times. In addition, doctors have identified cases of patients who, after testing positive for Covid-19, subsequently tested negative during a serological test, as if they had not developed antibodies or if it disappeared from the body the latter between the two tests. “At this time, we do not yet have enough data on immunity to Covid-19 to draw definitive conclusions “, emphasizes Laurence Weiss, immunologist at Georges-Pompidou European Hospital, quoted in Liberation on October 13.
In Singapore had a newborn at birth, antibodies against the corona virus, The Straits Time reports daily. This baby was born to a mother who was infected with Covid-19 during her pregnancy in March 2020 during a trip to Europe. At the birth of the child “my pediatrician said the antibodies I developed against Covid-19 were gone, but Aldrin [le bébé] had some. My doctor assumes that I passed my antibodies to him during pregnancy. ” An interesting case for scientists who still know little about the link between infection and the development of antibodies.
Reminder of coronavirus symptoms
The first symptoms of the “new coronavirus” are not very specific : headache, muscle pain (stiffness), severe tiredness. Fever and respiratory symptoms (cough, respiratory failure, shortness of breath …) occur later, often two or three days after the onset of symptoms. Loss of taste (ageusia) and loss of smell (anosmia) are now considered warning signs of a coronavirus infection.
A healthy carrier of a virus does not show clinical signs of infection:
- either because it is an infectious agent (virus, bacteria, etc.) somewhat virulent : the agent is too weak to cause body reactions and thus symptoms.
- either because his immune system is very effective (it develops more antibodies than average) and prevents the onset of symptoms.
You can be a healthy carrier of various viruses and diseases: chicken pox, influenza, hepatitis B, tuberculosis, an STI such as chlamydia, HIV (AIDS) and herpes …
We can also be healthy carrier of a gene as is the case for certain genetic diseases and therefore not contagious (Cystic fibrosis for example). In this case, the genes are passed on from parents to their child. Each child inherits half of their genes from their father and the other half from their mother. In France, More than two million people are believed to carry the cystic fibrosis gene without knowing it: we call this “healthy carriers”. They are at risk of passing the disease gene to their child, but without developing the disease, says Orphanet, the information portal dedicated to rare diseases.
These two concepts have roughly the same definition. A healthy carrier and an asymptomatic subject are both infected but do not show clinical signs related to the infection. Small subtlety though:
- In the case of an infectious disease (for example a healthy carrier of a virus) we speak of a ‘healthy carrier’ or a hereditary disease. On the other hand, with a metabolic disorder (diabetes, arterial hypertension …) one cannot speak of a “healthy carrier”.
- We speak of an “asymptomatic” person for an infectious disease, a genetic disease or for metabolic disorders.
According to December 3 report from Public Health France:
- 50% of people who are positive for the coronavirus show symptoms (data available for 53,533 cases) and 50% show no symptoms. This percentage is stable compared to the previous week.
- 72% of people tested coronavirus from November 27 to December 3 declared itself symptom-free, a figure slightly higher than the week before (71%).
. Change in the number of confirmed SARS-CoV-2 cases and positivity rate according to the presence or absence of symptoms (1,740,588 cases described), by week since week 23/2020, mainland France (data as of December 2, 2020)
In June, Chinese researchers from the infectious disease division of Zhongnan Hospital in China wanted to learn more about the profile of people most likely to be asymptomatic. For this they analyzed the health status of 78 patients who were infected with the coronavirus, including 33 healthy carriers. Symptoms and signs, such as fever, fatigue, and dry cough, were monitored daily. At the end of their study, published in the journal Jama Network, they found that asymptomatic people:
- Were average 37 years (compared to 56 years for symptomatic people)
- Women were inside 67% of the cases. In other words, two out of three healthy carriers are women.
- Presented less liver damage (liver) than symptomatic people.
- Had a high percentage of it helper T lymphocytes (CD4 +: they play a major role in the secondary immune response), “suggesting that the damage to the immune system was less than in symptomatic infections “, indicate the authors of the study.
Anyone can be a ‘healthy carrier’ and thus participate in the spread of the disease without realizing it. When in doubt, even if one does not “feel sick”, everyone should:
- Avoid any contact with vulnerable people (pregnant women, the chronically ill, the elderly, etc.).
- Do not go to places where there are vulnerable people (hospitals, maternity clinics, care facilities for the elderly, etc.).
- Respect the basic “barrier” gestures: wash your hands regularly (water + soap) or use a hydroalcoholic solution, cough or sneeze into your elbow, or in a tissue, use disposable wipes (and throw them in the trash after first use). greet without shaking hands, without hugs and keep a distance of at least 1 meter from a conversation partner.
- Wear a mask in confined spaces, as well as outdoors, including places where it is not mandatory
- Test for suggestive symptoms.
Source: COVID-19 quick summary. Proportion of asymptomatic forms and transmission of SARS-CoV-2 in the presymptomatic phase. Saint-Maurice: Public Health France, July 8, 2020