Controversy over the period of isolation against Covid-19

Experts in the US and France propose to shorten the time of self-isolation because they believe that people infected with nCoV only spread the virus most strongly 5 days after the onset of symptoms.

In November, Dr. Muge Cevik, an expert in Infectious Diseases, University of St. Mary. Andrews, USA, and colleagues publish a report in the Lancet. Accordingly, they believe that Covid-19 patients are most contagious two days before and 5 days after symptoms begin.

The team analyzed the path of nCoV infection, then compared it with SARS and MERS. They looked at nearly 1,500 studies published between 2003 and 2020 on the transmission times of thousands of people. Most of them were so ill that they were hospitalized.

The team found that both asymptomatic and non-symptomatic patients carried the same amount of nCoV. But asymptomatic people seem to clear the virus from the body faster. The analysis concludes that people with Covid-19 are most contagious one or two days before and about 5 days after the first manifestation. However, they can carry the genetic codes of the virus (not a live virus) in the nasal cavity and throat for up to 17 days. In particular, some cases last for three months.

Elderly people tend to be infectious with COV for longer. But there is no evidence that the virus lives longer than 9 days after onset of symptoms. The positive results are then due to the test kit that detects the genetic segments, not the live virus, because the spread peaks relatively quickly during the disease, health workers at public clinics are at risk. chances of viral infection were higher than those working in the intensive care unit.

The new study raises the question: Should the quarantine period be shortened so that people can comply more seriously? Should this time be extended to thoroughly prevent cases in the community?

In July, the US Centers for Disease Control (CDC) reduced its quarantine recommendation from 14 days to 10 days. But this is still a long time for many people. The patient may have financial problems, or may not feel that his or her illness is not serious enough to do this. The agency is considering further shortening and issuing the latest guidance next week.

“If the quarantine period is shorter, more people will be willing to adhere to the principles of public health,” said Angela Rasmussen, virus specialist at the Center for Global Health Science and Security at Georgetown University. “.

A medical staff took a sample of a driver’s nasal fluid at a mobile testing station in Oakland, California. Image: NY Times

In September, France reduced the self-isolation threshold from 14 days to 5 days for people with nCoV and F1 exposure. “Setting a 5-day quarantine period seems pleasant and helps to encourage more serious compliance,” says Dr. Cevik.

A UK survey conducted in September found that only one in five of those respondents were comfortable with a 10-day quarantine. Even if we do more testing, if we cannot ensure that people are quarantined according to the rules, they don’t think we can control the spread of the virus.

In the United States, many people wait about one to two days after symptoms appear to be tested. With the current delay, they get their results two or three days later, by the end of the time the virus is actively spreading in the body.

Dr. Michael Mina, a virus specialist at Harvard University, said: “Even with the PCR test, when you get the results, 90% of the viral transmission is done. This study shows the time to spread. How short is a person’s infection “.

Dr. Megan Ranney, of Brown University’s emergency department, says some patients can carry the virus in their lungs about eight days after the onset of symptoms. For these individuals, the quarantine period can be longer than 5 days.

The new analysis still has some limitations. Elderly people or severe infections can be contagious for longer than a week. However, if the shortening of the quarantine period makes people more willing to cooperate, its benefits to the community outweigh the risks, says Dr. Stefan Baral, an epidemiologist at Hopkins University.

Some countries have adopted quarantine support policies. In May, the Japanese government asked young, symptomatic patients to stay at home for four days before going for tests. The country’s guidelines require patients to consult a doctor over the phone and only get tested if there is a high chance of infection. Anyone with a positive result is admitted to a hospital or hotel for quarantine. In the US, New York City and Vermont have a similar policy.

Thuc Linh (According to the NY Times)


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