According to the best data available, the period during which a person infected with COVID-19 may continue to be infected is as follows:

Students take a quick COVID-19 test.

People get rid of the virus at different speeds, so the length of time they get infected varies.Ben Hasty / Media News Group / Reading Eagle / Getty Images

  • UK health authorities have estimated the effects of various quarantine periods on COVID-19 infectivity.

  • Five days after symptoms or a positive test, they said that 31% of people infected with COVID-19 were contagious.

  • They said that a negative test on the 5th and 6th day of rapid testing reduced the risk of infectivity to 7%.

This is an important question that came to the minds of COVID-19 individuals who would like to meet their friends and relatives again. How much do I need to quarantine to prevent transmission?

So far, there seems to be no universally accepted answer.

In the United States, it is permitted by government regulations Most people End quarantine after 5 days without taking the test. In contrast to the UKBritish people with COVID-19 can be discharged on the 6th day, but only if they are negative in quarantine for the last 2 days and have no fever. Without testing, they have to wait a full 10 days.

Policy makers must strike a balance between limiting the progress of the pandemic while preventing the economy from stagnation. Dr. Anthony Fauci, President Biden’s Chief Medical Adviser, said: December 28 Its US COVID-19 Quarantine Guidelines were designed to “return people to work.”

However, some disease experts in both the UK and the US have quarantine guidance. Don’t follow science And there is a risk that people will inadvertently spread the virus at work or school, especially if they have not been tested.

Robert Wachter, Professor and Dean of Medicine, University of California, San Francisco I said on Twitter on January 14th, His son’s rapid test was positive on day 10. “If we hadn’t inspected, he would be on the third day of work,” he said.

UK Health and Safety Agency, This informs UK policyIt is estimated that nearly one-third of patients with COVID-19 are still contagious 5 days after the onset of symptoms or a positive test. According to the model, only 7% of those who were isolated for 5 days and were negative on the 5th and 6th days of isolation were still contagious. By the way, the data shows that the number of infected people after 10 days is 5%.

Gary MacLean, a professor of molecular immunology at London Metropolitan University, told insiders that people with COVID-19 were generally “potentially infectious” from 2 days to 10 days after symptoms.

McLean said it was quite possible that the infectivity would disappear, according to UK guidance, but that was not absolutely certain. He said the immunity and the number of viral particles they infected could determine how long the patient remained infected. “Everyone is a little different,” he said.

The estimates are not specifically related to Omicron infections.

Lawrence Young, a virologist and professor of molecular oncology at the University of Warwick, told insiders at the time of the data release that there was less data on the dynamics of Omicron infection compared to other variants. This means that it is not possible to accurately predict how infected a person will be infected with Omicron.

Both Young and McLean agreed that UKHSA data is the “best available” data to guide you in what to do if you are not sure if it is infectious. However, it may not be accurate in all cases.

Other initial data:


21 studies Vaccinated people admitted to Omicron showed peak levels of infectious viral particles 3-6 days after diagnosis or onset of symptoms. No infectious virus particles were detected after 10 days, according to the authors of the study.


Research by researchers at the University of Exeter, UK Published in the International Journal of Infectious Diseases It was found that 3% of the 176 participants had potentially infectious virus particles on day 10. Some people have retained these levels of virus for up to 68 days, they said. This study was conducted before Omicron became the most common subspecies.

Scientists at the London School of Economics and Tropical Medicine say that by requiring at least two consecutive days of negative tests, people can reduce the number of days they have been infected in the community to nearly zero. Said. This is not related to the number of days since the first positive test.

Researchers warned that the model uses pre-Omicron data. the study Not published or formally scrutinized by other experts in peer reviews.


Early studies in the United States suggested that both Omicron and Delta infections lasted for about 10 days, suggesting that Omicron people had low peak levels of viral particles. The method used does not necessarily predict infectivity, James Hay, Harvard TH Chan Public Health School Research Leader, Warning on Twitter.

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