Covid infection: the incubation period, before symptoms appear?
Health

Covid infection: the incubation period, before symptoms appear?

Until the summer of 2022, Covid-19 remains a highly contagious disease. The initial Sars-CoV-2 virus has infected 3 people, the Delta variant more than 6, the Omicron variant nearly 10, and its BA5 subvariant more infectious. Infectious period, before and after symptoms, asymptomatic …

Appeared in China in December 2019, Covid-19 infected more than 1 million people worldwide at the beginning of April 2020, evidence of highly infectious From its virus, the SARS-CoV-2. The Coronavirus transmission capacity Sars-CoV-2 is evaluated by Measure “R0”. This “R” corresponds to Reproduction rate of the virus indicates Number of people positive for Covid-19. The higher it is, the greater the transmission of the disease. The Release variantsfor the first timealpha Came from England then Delta Came from India and Omicron From South Africa they changed the game because they were Much more infectious From the original Sars-Cov-2 strain of 2020 BA.5 . sub-variable from Omicron The majority in France since mid-June are the most contagious than BA.2, which itself is already more transmissible than the BA1 omicron sub-strain Than “Demonstrates the evolutionary ability of a virus that is able to evade vaccines and at the same time increase its transmission” Infectious disease specialist Anne-Claude Crémieux explained on FranceInfo on June 22. At the end of July, the seventh wave landed with a Reproduction rate of virus that falls below the threshold of 1 (An infected person infects less than another person). French public health reports also a The rate of covid infection increased again Since December 2021. How many days are you ready When do you test positive for Covid? 5 days ? 10 days is isolation time? are we Contagious if there are no symptoms ? during the incubation period? Focus on knowledge.

Effective reproduction rate of COVID-19 in France as of July 23, 2022
Effective reproduction rate of COVID-19 in France as of July 23, 2022 © Gouvernement.fr

What is the definition of the term “infection”?

The word “infection” comes from the Latin Sperm which means “with” and “Tanger” To touch”. In medical parlance, infection is defined by the transmission of an infectious agent and, where appropriate, the corresponding disease, from an infected person to a healthy individual, by direct (skin, mucous membrane) or indirect (air (saliva, saliva) contact) …) and the digestive system …).

The Sars-CoV-2 virus is mainly spread by Case of close contact with an infected personby Expulsion of small liquid particles through the mouth where Through the nose if the affected person is coughing, sneezing, or talking Or take a deep breath. “You can also get Covid-19 when The virus enters the mouth, nose or eyesThis is a condition that is more likely when people are in direct or close contact (less than one meter away) with an infected person.” says the World Health Organization. You can also be contaminated if We touch our eyes, nose, or mouth Before washing your hands after touching a contaminated surface. The Increased transmission of the virus indoorsCrowded and not well ventilated.

Duration: What time is covid infection?

The infectious stage of a Covid-19 positive patient is at the beginning 8 days on average It starts around Two days before symptoms start. With the Omicron variable, Faster replicationProfessor Alain Fischer, head of the Vaccine Strategy Board in France, confirmed to Les Echos. So, Everything gets shorter, including the symptomatic – or asymptomatic – phase But it is contagious.

according to The study, conducted by Japanese researchers and published in January 2022, is Immunized Omicron cases are unlikely to clear the infectious virus 10 days after diagnosis or their symptoms (as was the case with the original virus, editor’s note). The amount of viral RNA (or “Viral burden”) was highest 3-6 days after diagnosis (testing) or 3 to 6 days after symptoms appearand then gradually decreased over time. We will be like this Contagious for a shorter period (6 days compared to 10 days) and not necessarily before symptoms appear with the Omicron variant.

How contagious is the Omicron variant?

The Omicron variant became the majority in France at the end of 2021 within a few weeks. The number of infections was doubling every 2-3 days in late November – early December, much faster than when the delta spread. According to the studies cited French public health, “Omicron is three times more transmissible than Delta”. “The UK professor of medicine claims that without buffer measures, R0 and Reproduction rate will be close to 10Epidemiologist Eric Dortensio of Inserm reported on TV5Monde, on December 31. The incubation period It is also shorter: Faster replicationAnd the Professor Alain Fischer, Chair of the Vaccine Strategy Board in France, emphasized Les Equus. So, Everything gets shorter, including the symptomatic – or asymptomatic – phase But it is contagious.” according to Japanese study published in January 2022, Viral load elevation 3-6 days after OMICRON diagnosis (test) or the appearance of symptoms. The majority of sub-variants of Omicron BA.2 in France until the beginning of June were “more contagious than its predecessor” (BA1) reported by Professor Arnaud Fontanet at the France Inter on 14 March. about 30% What’s more. And the camp The majority of BA5 now”It spreads better than BA.2″ Than “Demonstrates the evolutionary ability of a virus that is able to evade vaccines and at the same time increase its transmission” Infectious disease specialist Anne-Claude Crémieux explained on FranceInfo on June 22.

What is the incubation period for Covid?

The incubation period covers the period between infection with the virus and the appearance of the first symptoms. The average incubation period for Covid-19 is initially 5 days but has been reduced Omicron. As explained by Professor Yazdan Yazdanbana of the Scientific Council on BFM-TV on January 2, 2022,We are facing a variable that has a duration (nursery, editor’s note), before the onset of symptoms that lasted 5 to 3 days.” Thus we can be in contact with the virus and The first signs of contamination appeared after three days. During this period, a person can be infectious.

Viral load reaches its peak in the first week of illness.

How long do you remain contagious before symptoms of Covid-19 appear?

According to laboratory data, it is basically Before symptoms appear in infected people (that is, two days before the onset of symptoms) and at the beginning of the disease, the most infectious diseases are” to me The World Health Organization explained at the beginning of the Corona virus epidemic in 2022. Today, it is facing the changing OmicronResearch has not shown that people are contagious before their diagnosis (testing) or symptoms but Rather, during the first week. British meta-analysis collecting 79 studies on SARS-CoV-2 (5,340 people) published 19 November 2020 in the scientific journal scalpel It has already been shown that Viral burden Corona virus SARS-CoV-2 in the upper respiratory tract peaked during The first week of illness.

How long will you remain contagious after symptoms of Covid appear?

After the fifth day, the viral load decreases.

According to the authors of Study English Lancet Posted in November 2020, The peak of infection for a person infected with the Covid-19 virus continues until the fifth daye A day after symptoms appear. After that, the viral load decreases. According to Japanese analysis in January 2022 on cases OmicronThis viral load will be a maximum 3 to 6 days after diagnosis or symptoms appear Then it will go down. The authors also considered that it was Immunized Omicron cases are unlikely to clear the infectious virus 10 days after diagnosis or their symptoms.. Therefore, infection is particularly strong in the first week after symptoms appear. The World Health Organization also reports that “People who develop a severe form Could be disease contagious longer.”

Are you contagious when you have no symptoms of COVID (asymptomatic)?

A person who is infected with Sars-CoV-2 but does not have symptoms is contagious and can infect other people. Similarly, a person who is not showing symptoms can also transmit the virus though “It is not yet clear to what extent this is happening.” says the World Health Organization. Note that if asymptomatic cases are contagious, “Transmission of Covid-19 occurs mainly from people who show symptoms” Refers to agency.

What are the risks of contracting Covid twice or more?

French public health reports on July 7 a The rate of covid infection increased again Since December 2021, Omicron variable prevalence (12% of confirmed COVID-19 cases in Week 23 (6-12 June 2022) were probable re-infection). A large number of re-infections with omicron have been observed after the first infection with this same species. However, the probability of re-infection after the first infection with another variant (alpha, delta, etc.) is higher. “The The risk of re-infection increases with the age of the first infection to reach a Shelf about 6 months after the first injury.

A contact case is a person who has been in contact without protective measures (such as a type 1 mask) with a person infected with the Covid virus. The longer and closer the contact, the greater the risk of contamination (more than 15 minutes, less than 2 meters)confirms the Ministry of Health. The 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 its intracorporeal route of entry. Thomas B Peacock 1. Department of Infectious Diseases, Imperial College London, UK, W2 1PG

Recommendations regarding 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 for patients suspected of having Covid-19. Endorsed by the College on June 18, 2020. Updated November 5, 2020. HAS.

How is COVID-19 transmitted? July 9, 2020. World Health Organization.

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