How long should you isolate if positive for coronavirus? CDC’s New Guide Says 10 Days, Not 14

Ariana Eunjung Cha, The Washington Post

Published

2:21 pm PDT, Tuesday July 21, 2020

The Centers for Disease Control and Prevention’s self-insulating rules have been a facet of pandemic life in the nation since March.

Those who test positive for the coronavirus but have no symptoms have counted the minutes until they can go free, while sufferers are concerned about how long they can be a danger to loved ones.

Now, the Centers for Disease Control and Prevention, acknowledging a greater understanding of the infectivity of the new coronavirus, have changed some of their recommendations.

He now advises most people with active cases of covid-19, the disease caused by the coronavirus, to isolate themselves for 10 days after the onset of symptoms and 24 hours after the fever is gone. For those who have a positive test but are asymptomatic, the public health agency as of Friday recommended isolating 10 days from the date of the test. The CDC had previously recommended that people isolate up to two coronavirus-negative swabs, but that proved impractical due to a paucity of evidence.

In the six months since the virus has been in the United States, multiple studies have suggested that most people are infectious for a short period, usually four to nine days. In a large follow-up study of high-risk interaction contacts in hospitals and homes, people’s exposure to the virus occurred within five days of the patient’s illness.

The CDC noted that a “limited number of people with serious illness” may continue to produce the virus longer and may warrant extending the isolation period to 20 days.

As with other coronavirus guidelines, many things continue to change and there are different opinions in different parts of the world about how long people should be isolated or quarantined.

Isolation rules are for people who test positive, while the term quarantine is generally used for people who have been in contact with an infected person but do not have confirmed infections. CDC continues to recommend a 14-day quarantine period.

Switzerland requires people to isolate themselves for 10 days, but some have argued that it is still too long. In Taiwan, travelers from low-risk countries like New Zealand, South Korea, and Vietnam must be quarantined in a hotel for just seven days. Visitors from higher risk countries are still subject to a 14-day rule.

The World Health Organization updated its guideline in June to recommend 10 days of isolation for those without symptoms and at least 13 days for people with symptoms.

Julian Tang, a virologist at the University of Leicester in the United Kingdom and the National University of Singapore, said he has been advising clinical teams for several months that patients can be released from isolation within 10 days. He said documents examining when people are able to spread the virus have been remarkably consistent over the time frame for potential transmission.

In an article in Nature, the researchers found that the virus begins to neutralize itself with antibodies that appear on the fifth day of an infection and that no live virus was detected on the eighth or ninth day. A study of nasal swabs and viral load published as a letter in the New England Journal of Medicine found that the amount of the virus appears to decrease almost from the first day of symptoms.

“It is not going to achieve absolute zero risk,” Tang said, “but studies have shown that virus shedding stops mainly after 10 days.”

The CDC expressed similar sentiments in its recommendations, which contain the caveat that they are based on the best information available and “reflect the realities of an evolving pandemic.”

“Even for pathogens for which there are many years of data available,” the CDC stated, “it may not be possible to make recommendations that ensure that 100 percent of people who are removing replication-competent viruses remain isolated.”