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A small study found that at-home rapid tests are less likely to catch omicron than PCR tests in the early days of an infection, the latest scientific wrinkle to complicate the constantly changing flowchart of our pandemic lives.
Many Americans have been relying on rapid tests to tell them if they have been infected at a time when hundreds of thousands of people in the U.S. are testing positive every day in the aftermath of the holiday season.
The research, published Wednesday as a preprint, meaning it’s preliminary and has not been peer-reviewed, examines 30 fully vaccinated workers in Los Angeles, New York, and San Francisco who were tested daily in December using both nasal antigen and saliva PCR tests. The study did not disclose how many participants had received a booster but said they were “highly boosted by choice.”
The takeaway? “Most omicron cases were infectious for several days before being detectable by rapid antigen tests,” the researchers concluded.
The rapid tests used in the research are two of the most popular options: Abbott Laboratories’
ABT,
BinaxNow and the Quidel Corp.
QDEL,
QuickVue tests. The study found it took about three days from the first positive PCR to detect the virus with an antigen test. Four people in the study transmitted the virus before finding out they were positive.
“[The] results strongly suggest that we will be unable to effectively test our way out of the current surge, even if we each had a week’s supply of rapid tests on the counter,” Daniel Larremore, a University of Colorado Boulder researcher who was not involved in the study, told STAT.
In short, this could mean that someone is infected even if they get a negative test result.
“It’s not a ticket that allows you to go back to normal or to drop any other measures,” Isabella Eckerle, a clinical virologist at the University of Geneva, said in an interview with the New York Times.
Rapid tests, which are cheaper than PCRs and can be used at home, are in high demand given the recent surge in cases. They can be difficult to find right now. However, the wait to get a PCR test, most of which are performed by health care professionals, can sometimes take hours, and then individuals have to wait for sometimes days to get their results.
The accuracy and availability of COVID-19 tests have become a front-and-center issue in recent weeks.
As part of the Centers for Disease Control and Prevention’s decision to shorten isolation periods for people with COVID-19 to five days from 10 days, the agency also said people can stop isolating at the five-day mark without a negative test and as long as they have no symptoms has further muddied the issue.
The policy change has been criticized by public-health experts who say the CDC’s decision-making has more to do with the lack of tests than the science, and it could lead to more people getting sick. (The CDC tweaked the policy this week, to say people who have access to testing should use an antigen test on day five of their isolation period. If they test negative, they can leave isolation and are expected to wear a mask around others for five more days. If they test positive, they should remain isolated for five more days.)
“I think they should have just told the truth,” Dr. Bob Wachter, chair of the department of medicine at the University of California, San Francisco, told “Pod Save America” this week. “You know, ‘We have a limited number of tests. And if you can’t get a test and you feel perfectly fine, we think the risk of you going out into civilization is quite low.’”
“The message they put out was the tests don’t work very well on day five,” Wachter added. “That’s just wrong. That’s just not right. They work perfectly fine. They’re great for that. They don’t work super well with omicron on day one.”
The American Medical Association, an influential organization that represents U.S. doctors, has jumped into the debate, calling the CDC’s new policy “confusing” and “counterproductive.” The AMA said Wednesday that the CDC’s own data show that 31% of people with COVID-19 are still infectious five days into their isolation.
“A dearth of tests at the moment does not justify omitting a testing requirement to exit a now shortened isolation,” the AMA said in the statement.
CDC director Rochelle Walensky said Wednesday that “this has nothing to do with the shortage of available tests.”
Other COVID-19 news to know:
• More than 4,000 children were hospitalized with COVID-19 in the U.S. on Wednesday, according to data gathered by the Washington Post. This includes confirmed and suspected COVID-19 cases.
• Italy plans to require COVID-19 vaccines for anyone who is at least 50 years old and in the workforce, according to Politico. People who fall into this category have to demonstrate vaccination or that they have recently recovered from COVID-19 by mid-February.
• One in 400 people in the U.S. have died of COVID-19, BNO News tweeted on Thursday.
• As a result of the omicron surge in the U.S., the Grammy Awards, set for Jan. 31, has been postponed to an undisclosed date, and the Sundance Film Festival will now take place online, reports NPR. This follows the news that the Golden Globes, scheduled to occur Sunday, will not be televised, have no audience, and have a red carpet.
What the numbers say
The U.S. reported 704,369 new COVID-19 cases on Wednesday, according to the New York Times tracker. The seven-day average for cases rose for the 24th-straight day to a record 585,535 on Wednesday and is up 247% in two weeks.
COVID-19 hospitalizations have increased every day since Nov. 11. There are now 110,334 people who are hospitalized with COVID-19. That’s up 58% from two weeks ago and the highest level since last January’s surge. The number of people dying of COVID-19 is also increasing; there were 2,113 COVID-19-related deaths on Wednesday. The seven-day average of COVID-19 deaths is 1,329, which is down 3% from two weeks ago.
The number of fully vaccinated people in the U.S. ticked up to 206.80 million, or 62.3% of the population, while only about 34% of people aged 5 years to 17 years have been vaccinated, according to CDC data.
—Tomi Kilgore
