Calls Mount to Cut Covid-19 Quarantine Period for Fully Vaccinated Who Test Negative

The move comes as some researchers and business leaders have started calling for a shorter timetable for all fully vaccinated people who have cleared their infections, saying it is supported by a growing body of research and rising numbers of vaccinations and rapid tests.

The U.K. changed its quarantine rules on Wednesday, cutting the quarantine time to seven days for vaccinated people who twice test negative, to allow them to return to work faster, easing the burden on overstretched public services and businesses, the government said.

The debate suggests pandemic-response measures may be shifting, as new tools for fighting the virus take hold and fatigue with restrictions grows.

A vaccinated person with no symptoms or mild ones could end a four- or five-day isolation period if two rapid tests indicate they don’t have the virus, said Dr. Saad Omer, director of the Yale Institute for Global Health. “That would be my recommendation to go in that direction, and I would urge the CDC to reconsider this and make that recommendation,” he said.

Unvaccinated people should follow the CDC’s recommended periods of isolation and quarantine, Dr. Omer said, as should vaccinated people who show symptomatic infections.

For hospitals and businesses with essential workers, shorter quarantines could help limit employee shortages that disrupt operations, especially as the Omicron variant races across the U.S.

“Healthcare workers, first responders, airline professionals and many other essential employees across the economy who are fully vaccinated may no longer need a full 10-day isolation,” JetBlue Chief Executive Robin Hayes said in a letter to the CDC Wednesday.

Delta Chief Executive Officer

Ed Bastian,

along with the airline’s chief medical officer and a medical adviser, sent a letter on Tuesday asking the CDC to consider five days of isolation and a testing protocol.

“With the rapid spread of the Omicron variant, the 10-day isolation for those who are fully vaccinated may significantly impact our workforce and operations,” they wrote.

Under the CDC’s new guidelines, healthcare workers can resume work within seven days following a negative test, or potentially even sooner in a staffing crunch. Also, healthcare workers who are fully vaccinated and who got a booster wouldn’t need to quarantine after high-risk exposure to the virus.

“As the healthcare community prepares for an anticipated surge in patients due to Omicron, CDC is updating our recommendations to reflect what we know about infection and exposure in the context of vaccination and booster doses,” CDC Director

Rochelle Walensky

said.

The CDC technically distinguishes between isolation, which is for people who have a confirmed infection, and quarantine, which is for people exposed to the virus.

The U.K. shortened the isolation period for fully vaccinated people who test positive for the virus to seven days from 10, provided they test negative using a rapid antigen test on the sixth and seventh days of their stretch in isolation. The tests must be taken 24 hours apart.

“We want to reduce the disruption from Covid-19 to people’s everyday lives,” Health Secretary

Sajid Javid

said Wednesday.

Under the U.K.’s new rules, people still showing symptoms, especially fever, after seven days should keep isolating even if their tests are negative. It advised people leaving isolation after seven days to work from home, wear a mask indoors with others and avoid contact with vulnerable people for a few days longer.

Unvaccinated people who are close contacts of a Covid-19 case are still required to isolate for 10 days.

The changes were based on an analysis by the U.K. Health Security Agency that found a regime of seven days of isolation and two negative test results has nearly the same effect at reducing the spread of the virus as 10 days.

Current CDC guidelines recommend people infected with the virus isolate for 10 days from the day symptoms develop or from a positive test result, while anyone who is a close contact of someone infected and isn’t fully vaccinated should quarantine for seven to 14 days, depending on whether they got tested and if the result was negative.

The CDC recommends fully vaccinated people quarantine only if they have symptoms but should get tested five to seven days after exposure and wear a mask for 14 days until their test result is negative.

The new coronavirus multiplies in the nose and throat of a person with Covid-19, and escapes in droplets and particles when that person breathes out, according to scientists. Someone else can pick up the virus if they breathe in those particles for a prolonged period, or if a large enough number of particles land on the eyes or in the nose or mouth.

Vaccines activate the body’s immune defenses and reduce viral replication. In addition to making severe disease less likely, vaccines reduce the chance that a person will transmit the virus, said Paul Bieniasz, a virologist at the Rockefeller University.

Some of the best recent evidence on how long someone can transmit the virus comes from an eight-month study of breakthrough infections among National Basketball Association volunteers.

In the study, published earlier this month in the New England Journal of Medicine, researchers said the unvaccinated were infectious for up to eight days, two days longer than the vaccinated, who cleared infections in under a week.

Studies performed before Omicron’s arrival didn’t find a meaningful difference in the period of infection caused by different variants.

Another reason to reconsider the 10-day quarantine period, health experts said, is the increasing availability of rapid tests that make it easier for people to test themselves before safely returning to work.

“The trade-offs that society is willing to make, and the availability of tools such as rapid tests, has changed,” said Dr. Jay Varma, director of Weill Cornell Medicine’s Center for Pandemic Prevention and Response.

—Alison Sider

contributed to this article.

Write to Nidhi Subbaraman at Nidhi.Subbaraman@wsj.com and Jason Douglas at jason.douglas@wsj.com