Daily coronavirus tests at home? Many experts are skeptical

In the past few weeks, a Harvard scientist has made headlines for a bold idea to contain the spread of the coronavirus: Introduction of so-called antigen tests, a Decades old Outsider in testing technology for tens of millions of Americans for almost daily home use.

These tests aren’t very good at picking up low-level infections. But they’re cheap, convenient, and quick, and deliver results in minutes. Real-time information, argued Dr. Michael Mina, would be much better than that long delays Clogging of the test pipeline.

The quick and frequent testing approach has drawn attention from scientist and journalists around the world as well Top officials in the Ministry of Health and Human Services.

Fast tests that are used often enough and widely enough could “Really squeeze the virus“Said Dr. Mina.” I think it’s crazy not to find out. “

But more than a dozen experts said that antigen testing is nearly ubiquitous while fascinating in theory, might not fly in practice – and is unlikely to be a pandemic panacea. The plan not only poses logistical hurdles for Hercules, but also depends on broad buy-in and compliance by a country that is full of people who are increasingly disaffected with testing for the virus. And that requires rapid tests can achieve their intended purpose at all.

“We’re open to thinking outside the box and finding new ways to deal with this pandemic,” said Esther Babady, director of the clinical microbiology service at Memorial Sloan Kettering Cancer Center in New York. However, antigen tests that might work at home have not yet hit the market, she said.

And yet no one has done a rigorous study to show that quick and common trumps in the real world are delicate, but slow. She said: “The data for this is missing.”

While quick and frequent testing might work, what has been said so far about the approach has been “largely focused and we need to compare it to reality,” said Dr. Alexander McAdam, director of the Infectious Disease Diagnostic Laboratory at Boston Children’s Hospital, which recently co-authored an article on pandemic testing strategies in the Journal of Clinical Microbiology.

Most of the coronavirus tests performed to date are based on a laboratory technique called PCR, which has long been considered the gold standard for diagnosing infectious diseases, as it can even absorb very small amounts of genetic material from germs such as the coronavirus.

However, the sputtering supply chains have hampered efforts to collect, ship and process samples for PCR, which has resulted in delays in turnaround times. The longer the waiting time, the less useful the result. PCR is also not cheap or easy to use, making it an unlikely candidate for widespread home use.

In the home arena, antigen testing could shine, said Dr. Mina. In the simplest of cases, they may work much like a pregnancy test, in which the body fluid is analyzed and a result is spat out within minutes, without the need for health workers or fancy machines.

According to Dr. Mina, these tests could be made from materials as cheap as cardboard and delivered like rations to communities across the country. They acted as bouncers at the entrances to schools or workplaces and enabled Americans to check themselves for the coronavirus at home several times a week, maybe even daily.

However, to achieve this reality would require an antigen test that has not yet been approved for widespread use and the infrastructure to mass-produce it. To date, only four antigen tests have received emergency approval from the Food and Drug Administration and are slated to be used by health care workers on people who have recently developed symptoms. All of them also rely on swabs to collect test samples, and three require somewhat bulky and expensive machines to read out the results.

“We don’t have any tests ready to occupy this space right now,” said Dr. McAdam.

Multiple companies have other Rapid tests in development. However, there is no guarantee that newcomers will F.D.A. Standards. And the last few months have clearly shown that no test is insensitive to bottlenecks.

“There is no reason to believe that the supply chain issues we encountered with all other coronavirus testing are no longer an issue here,” said April Abbott, director of microbiology for Deaconess Health System in Indiana. “We cannot build new product lines overnight.”

Experts also found that antigen testing is unable to filter out small amounts of the coronavirus, which means they are more likely to miss a case that a technique like PCR would catch. Some antigen tests only catch half of the infections they are looking for. And while some new products perform better in the lab, reported accuracy rates will almost certainly decrease when used at home, said Linoj Samuel, medical microbiologist with Henry Ford Health System in Michigan.

(Some have argued this PCR can even be too sensitive in some settingsIngesting remnants of harmless genetic material from the coronavirus from patients who are no longer ill; Antigen testing could work around this.)

Dr. Mina argues that quality degradation could be overcome with quantity: tests almost daily could identify infections on the threshold faster than the lagging PCR pipeline, which helps people isolate in time. From a public health perspective, the most important thing is to find people at the peak of the infection – something that even antigen testing should be able to achieve with high accuracy, he said.

Researchers don’t yet know how much virus someone needs to have in their body to be contagious – the amount will almost certainly vary from person to person. And there will inevitably be exceptions to the “more viruses, more transmission” trend.

“We just have no evidence that a negative test result means you are not infectious,” said Susan Butler-Wu, clinical microbiologist at the University of Southern California’s Keck School of Medicine. Some antigen tests are missing up to 18 percent of the time It has been shown by PCR to contain high levels of the coronavirus.

The opposite problem, false positives, are less common with antigen testing, but they do happen. In July, dozens of positive antigen tests with officials in Manchester, Vt. Prepared for an outbreak turned out to be a mistake. And in August, Ohio Governor Mike DeWine tested positive for the coronavirus through an antigen test just to test negative three times in a row by PCR.

In regions where the virus has only infected a few people, the number of false positives could eclipse the number of true positives.

Dr. McAdam said it is common to use a test with incomplete specificity in an area where the virus is rare. “It’s a bad idea and I’m going to die on this hill.”

High rates of inaccurate results, coupled with continued confusion over the spate of new coronavirus tests, could fuel public skepticism about science at a particularly precarious time, said Amanda Harrington, director of the clinical microbiology laboratory at Loyola University Medical Center in Illinois.

In the past six months alone, coronavirus testing has been billed alternately as game changer and national embarrassment, creating a feeling of perpetual whiplash among testing experts.

“My own family tell me that they are not sure what to believe,” said Dr. Harrington. “They undermine trust to the point where people don’t trust him anymore.”

And a nation of people who fear tests are less likely to take them, even if they are available at home.

Uma Karmarkar, a human behavior expert at the University of California at San Diego, said it was possible that compliance was low for the quick and frequent approach. She pointed to the example of daily medicines like birth control pills, as well as the spotty use of masks.

“Even if there is a vested interest, there is a slip,” she said. When tested almost daily, even cheap products could lead to high bills and further impair use. (Dr. Mina said the federal government should pay the bill to avoid this problem.)

A subset of people could still enthusiastically follow the quick and frequent approach, said Dr. Karmarkar. But that could be a skewed segment of the population, like those who are already more inclined to trust the medical system, and that could get worse pandemic health inequalities.

Until more data was collected to support the quick and frequent approach, Dr. Samuel proposes a preliminary middle ground. Schools, Universities and jobs, for example, can be good candidates for regular antigen testing, while hospitals and other health care facilities would continue to prioritize PCR.

“The whole idea is to use the right test for the right patient at the right time,” said Dr. Babady.

Dr. Mina agreed, noting that PCR continues to be vital in diagnosing sick patients – a situation that requires the most sensitive test in order for the correct treatments to be performed.

Still, he remains optimistic that the quick and frequent strategy could have a significant impact on the country’s coronavirus disaster. That should be incentive enough, he said, “I really think people want to use these tests.”