Coronavirus: How long does a person remain contagious?

✋ A test cannot tell how contagious you are.

A positive test for Covid-19 (PCR - Antigenic) means you have pieces of the virus in your body. However, a positive test doesn't always tell you whether or not you could pass the virus on to other people.

Only fragments of active viruses can infect other people. Studies suggest that the number of active viral particles in your body, and therefore the likelihood that you can pass the virus on to others, is highest during the first week of a COVID-19 infection.

If you have an active virus in your body, you can release aerosols and droplets that carry the virus. If someone inhales them, they can catch COVID-19 from you.

Scientists do not know how much of the virus a person must inhale to catch the virus.

⚡ RT-PCR Covid-19

The test that uses a method called reverse transcription polymerase chain reaction (RT-PCR) to search for the genetic material of the virus can return a positive result even after you no longer have active infection but you still have inactive (dead) pieces of virus in your body

⚡Covid-19 serology (CDC recommendations)

CDC does not recommend using antibody tests to diagnose current infection. Depending on the time a person was infected and the time of the test, the test may not detect antibodies in a person currently infected.

Furthermore, it is not currently known whether a positive antibody test result indicates immunity against SARS-CoV-2; therefore, for the time being, antibody tests should not be used to determine whether an individual is immune to reinfection. Antibody testing is used for public health surveillance and epidemiology.

Since antibody tests can have different targets on the virus, specific tests may be needed to assess antibodies from a past infection versus those from vaccination

👉 How do I know if I'm still contagious?

🏿 According to Harvard Health Publishing :

“By the 10th day after the onset of COVID symptoms, most people will no longer be contagious, as long as their symptoms continue to improve and their fever disappears. People who test positive for the virus but never develop symptoms within 10 days of testing are probably no longer contagious, but again, there are documented exceptions.”


🏿 According to CDC :

❏ CDC recommends that people with COVID-19 be able to interact with others if :

❍ Patients with mild to moderate illness who are not severely immunocompromised:

  • At least 10 days have passed since the onset of the first symptoms and
  • At least 24 hours have passed since the last fever without the use of antipyretic drugs and
  • Symptoms (e.g., cough, shortness of breath) improved

❍ Asymptomatic patients throughout their infection and not severely immunocompromised:

  • At least 10 days have passed since the date of their first positive viral diagnostic test.


❍ Patients with serious to serious or severely immunocompromised diseases:

  • At least 10 days and up to 20 days have passed since the onset of the first symptoms and
  • At least 24 hours have passed since the last fever without the use of antipyretic drugs and
  • Les symptômes (p. ex., toux, essoufflement) se sont améliorés
  • Consider consulting with infection control experts

Severely immunocompromised patients may produce a virus capable of replicating beyond 20 days after the onset of symptoms or, for those who were asymptomatic throughout their infection, the date of their first positive viral test. Consultation with infectious disease specialists is recommended. The use of a test-based strategy to determine when transmission-based precautions may be interrupted may be considered.

According to a of 129 people (690 samples) ,30 were immunocompromised, hospitalized with COVID-19. The median time participants continued to excrete the virus was 8 days after the development of the first symptoms. At 15.2 days, the chances of continuing to eliminate the virus were less than 5%.

CDC : 95 % des patients gravement ou gravement malades, y compris certains atteints d'immunodépression grave, n'avaient plus de virus capable de se répliquer 15 jours après l'apparition des symptômes ; aucun patient n'avait de virus capable de se répliquer plus de 20 jours après l'apparition des symptômes. La récupération du virus capable de se répliquer a été signalée chez des patients gravement immunodéprimés au-delà de 20 jours et jusqu'à 143 jours après un résultat positif au test SARS-CoV-2.


References

Harvard Health Publishing

OMS

National Academy of Sciences.

Coronavirus disease (COVID-19): How is it transmitted?

Healthline Media UK : When are you contagious with COVID-19?

CDC : Interim Guidance on Ending Isolation and Precautions for Adults with COVID-19

CDC : Overview of Testing for SARS-CoV-2 (COVID-19)

CDC : Test for Current Infection

CDC : Quarantine and Isolation

CDC : Interim Guidance on Ending Isolation and Precautions for Adults with COVID-19

Duration and key determinants of infectious virus shedding in hospitalized patients with coronavirus disease-2019 (COVID-19)

Coronavirus: How long is a person contagious?

Discontinuation of Transmission-Based Precautions and Disposition of Patients with SARS-CoV-2 Infection in Healthcare Settings