The circulation of the Covid virus accelerates at the beginning of December and it is still very contagious. The initial Sars-CoV-2 infected 3 people, the Omicron variant almost 10 and its BA5 sub-variant even more. The viral load would peak during the first week of illness.
Appeared in China in December 2019, the Covid-19 disease had infected more than a million people worldwide at the beginning of April 2020, proof of the high contagiousness of his virus, the SARS-CoV-2. The coronavirus transmission capacity Sars-CoV-2 is evaluated through the measurement of “R0”. This “R” corresponds to the reproduction rate of the virus and indicates the number of people infected by a positive case of Covid-19. The higher it is, the more the disease is transmitted. The release of variantsfirst theAlpha came from England then the Delta came from India and the Omicron from South Africa changed the game because they were much more contagious than the original Sars-Cov-2 strain of 2020. The sub-variant BA.5 of Omicron majority in France since mid-June is even more contagious than its predecessors. the reproduction rate is again greater than 1 in December, proof that contamination is resuming. how many days are you contagious when you are positive for Covid? 5 days ? 10 days is the time of isolation? Are we contagious if there are no symptoms ? During the incubation period? Focus on knowledge.
What is the definition of the term “contagion”?
The word “contagion” comes from the Latin “cum” which means “with” and “tangere” to “touch”. In medical language, contagion is defined by the transmission of an infectious agent and, where applicable, the corresponding disease, from an infected subject to a healthy individual, by direct contact (skin, mucous membrane) or indirect (airborne transmission (saliva , postillions…), digestive…).
The Sars-CoV-2 virus spreads mainly by case of close contact with an infected personby small liquid particles expelled through the mouth Where through the nose if the infected person coughs, sneezes, speaks or take a deep breath. “You can also contract Covid-19 when the virus enters the mouth, nose or eyesa more likely situation when people are in direct or close contact (less than one meter away) with an infected person” says the WHO. You can also be contaminated if we touch our eyes, nose or mouth before washing your hands, after touching a contaminated surface. The transmission of the virus is increased in indoor spacescrowded and insufficiently ventilated.
Duration: how long are you contagious when you have the Covid?
When the Covid virus appeared at the end of 2019-beginning of 2022, the duration of contagion extended from 2 days before the onset of symptoms to continue up to 8 days on average. With the Omicron variant, “replication is faster than everything gets shorter, including the symptomatic – or asymptomatic phase but contagious” explained Professor Alain Fisher, head of the former Council for Vaccine Strategy for France, to the Echoes in January 2022. According to a japanese studythe amount of viral RNA (or “viral load“) of Covid-positive patients is mostly high 3 to 6 days after diagnosis (test) or after the appearance of their symptoms and then gradually decrease. We would therefore be contagious for about a week but this duration of contagiousness varies according to the individual recalled the president of Covars (new “Scientific Council”) Brigitte Autran on October 10 on France Inter: “The viral load varies enormously depending on the severity of the disease and the symptomatology. We do not excrete the same quantities of virus if we have a virus that infects the nose rather than the throat. Of course there is a proportionality between the number of viral particles that we produce and the number of contaminations what we might do.”
How contagious is the Omicron variant?
The Omicron variant became the majority in France at the end of 2021 in just a few weeks. The number of infections was doubling every 2-3 days in late November-early December 2021, much faster than when the Delta spread. According to studies reported by Public Health France, “Omicron is about 3 times more transmissible than Delta”. “A professor of medicine in the United Kingdom claims that, without barrier measures, the R0, the reproduction rate would be close to 10” informed the epidemiologist Éric d’Ortenzio of Inserm on TV5Monde, the 31st of December. Invited by France Inter in October 2022, the president of Covars Brigitte Autran recalled that “the viral load varies enormously depending on the severity of the disease and the symptomatology”therefore from one individual to another. “We don’t excrete the same amounts of virus if we have a virus that infects the nose rather than the throat.” Understand that the more the symptoms are present, the more the person would transmit the Covid virus.
What is the incubation period for Covid?
The incubation covers the period between infection with the virus and the appearance of the first symptoms. The median incubation period for Covid-19 is initially 5 days but has been reduced with Omicron. This duration”before the onset of symptoms went from 5 to 3 days” explained Professor Yazdan Yazdanpanah of the Scientific Council on BFM-TV on January 2, 2022. We can thus be in contact with the virus and have the first signs of contamination three days later. During this period, the person can be contagious. A meta-analysis published in August 2022 in the JAMA Network by Chinese researchers based on 142 publications (8112 Covid patients) confirmed the reduction in the incubation period of the virus with Omicron. Precisely :
- 3.4 days with the Omicron variant.
- 4.4 days with the Delta variant
- 5 days of incubation with the Alpha variant
Viral load peaks in the first week of illness.
How long are you contagious before the onset of Covid symptoms?
“According to laboratory data, it is mainly just before infected people develop symptoms (incubation phase, editor’s note) and at very beginning of the disease that they are the most contagious” has explained the WHO in 2020. Research conducted on positive cases for the Omicron variant showed contagion during the first week.
How long are you contagious after the onset of Covid symptoms?
According to Japanese analyzes of January 2022 on cases Omicronthe viral load of the virus would be maximal 3 to 6 days after diagnosis or onset of symptoms then would decrease. The authors also considered that it was “unlikely that vaccinated Omicron cases will shed infectious virus 10 days after diagnosis or the appearance of their symptoms”. The contagion is therefore particularly strong in the first week following the onset of symptoms. The WHO also informs that “People who develop a severe form disease can be contagious longer”. Similarly, those with more symptoms appear to be more contagious than asymptomatic cases. “We don’t excrete the same quantities of virus if we have a virus that infects the nose rather than the throat. There is a proportionality between the number of viral particles that we produce and the number of contaminations what we risk doing” explained Brigitte Autran on October 10 on France Inter.
Are you contagious when you don’t have symptoms of Covid (asymptomatic)?
A person infected with the Sars-CoV-2 virus but who has no symptoms is contagious and can infect other people. Similarly, someone who never develops symptoms can also transmit the virus even though “it is not yet clear to what extent this is happening” says the WHO. Note that if asymptomatic cases are contagious, “Covid-19 transmission occurs mainly from people with symptoms” indicates the agency.
What is the risk of having the Covid 2 times or more?
Public Health France reported in July 2022 a increase in the proportion of Covid reinfections since December 2021, beginning of the distribution of the Omicron variant (12% of confirmed COVID-19 cases in week 23 (June 6-12, 2022) were possible cases of reinfection). A high number of reinfections with Omicron after a first infection with this same variant is observed. Nevertheless, the probability that a reinfection occurs after a first infection by another variant (Alpha, Delta or other) is even higher. “The probability of reinfection increases with the age of the first infection to reach a shelf about 6 months after the first infection”.
A contact case is a person who has been in contact without protective measures (such as a type 1 mask) with a Covid-positive person. The longer and closer the contact, the greater the risk of contamination (more than 15 minutes, less than two meters)emphasizes the Ministry of Health. A contact person must be tested on D+2.
Sources:
The SARS-CoV-2 variant, Omicron, shows rapid replication in human primary nasal epithelial cultures and efficiently uses the endosomal route of entry. Thomas P. Peacock1. Department of Infectious Disease, Imperial College London, UK, W2 1PG
Recommendations relating to the vaccination strategy. Senate press conference Thursday, July 1, 2021.
Covid-19 – Get vaccinated? Decide with your doctor. January 29, 2021. HAS
Vaccination against Covid-19: transparency, pragmatism and flexibility are the keys to an effective campaign. Press release. November 9, 2020. HAS.
Rapid responses in the context of Covid-19 – First-line care of patients suspected of Covid-19. Validated by the College on June 18, 2020. Updated on November 5, 2020. HAS.
How is COVID-19 transmitted? July 9, 2020. WHO.