Why, when and how to test for COVID-19 at home
Since we’ve been living with COVID-19 for almost two years, quick and accurate testing for COVID-19 remains an urgent priority. In fact, rapid tests could be key to preventing Delta or new variants of SARS-CoV-2 from leading to even larger outbreaks as schools reopen, companies resume operations, and people return to work.
But that is only possible if the testing is used correctly, at the right time and in the right place. With more opportunities for people to interact in public environments where the virus can spread, knowing who is infected and who may and may not be causing new COVID-19 infections has never been more important. But that doesn’t mean blanket testing, especially the rapid at-home tests now available from pharmacies and other retailers, will be the answer. Knowing when to use these tests and how to interpret the results are critical, experts say. And that means understanding what the tests can and cannot do.
What is the difference between home tests and the tests that a hospital, doctor’s office, or laboratory do?
the Approved home kits by the U.S. Food and Drug Administration (FDA) are antigen tests, which means they can pick up things that the virus makes or excretes, such as proteins, but not the actual genetic material of the virus. A positive antigen test thus picks up signs that the SARS-CoV-2 virus was or is present, similar to hair that people or pets lose as a trace of their whereabouts.
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Polymerase chain reaction (PCR) tests are the type healthcare facilities or testing laboratories are most likely to use. They detect the presence of viral genes. These tests are more sensitive, can even detect a whisper from the viral genes and amplify that signal, while it takes a certain amount of viral protein to set off the alarms for an antigen test.
This difference also indicates a big difference in when the tests are most helpful. PCR tests can determine the presence of old, inactive viruses for weeks and even months after infection, says Dr. Michael Mina, Assistant Professor of Epidemiology at Harvard TH Chan School of Public Health. This is why the CDC suggests that if you get a positive PCR test for COVID-19, you Wait for several weeks before doing another test to make sure the PCR isn’t still picking up the previous infection.
PCR tests can be more accurate, but since antigen tests require higher amounts of virus to get a positive result, these tests are much more likely to identify people who are infectious and who carry a heavy viral load around them who can spread easily and infect others can. For this reason, Mina has been very vocal about the need to increase availability and access to home testing so more people can reassure their COVID-19 status at the crucial moments: before going to school, before entering a restaurant , Workplace or sporting event, or before attending a small private gathering. For these situations, a real-time result is more reliable and reassuring than one from a PCR test performed a few days ago. “If you want to keep business going or have a safe dinner at home, don’t ask people to do a PCR test two days in advance,” says Mina. “Ask them to do a quick test within two hours of your arrival. If a quick test comes back negative two hours before the home visit, it is extremely unlikely that the person is contagious and poses a threat to others. It’s an extremely effective way to protect dinners, concerts, workplaces, and schools. Will it keep you 100% safe? No, but it will likely be 100% effective in keeping super spreaders from invading gatherings. “
Is a home test as reliable as a PCR test?
The gold standard test for diagnosing COVID-19 is a PCR test performed by laboratories. However, antigen tests are usually 80-90% reliable in detecting SARS-CoV-2 proteins, which are a warning sign that someone may be infected. These antigen tests are also particularly useful for determining when an infected person is most contagious and is likely to spread the virus to others.
Do you need a prescription for home testing?
There are now several home tests available without a prescription, without a prescription, including those from Abbott, Becton Dickinson, Ellume, OraSure, and Quidel. Generally, the kits contain two tests so people can repeat the test every day or two to check the results. The FDA also has one right now new COVID-19 test at home from Acon Laboratories.
How do home test kits work?
These kits, which are sold at pharmacies and other retailers such as Walmart and grocery stores, can be divided into two groups: collection kits for the home and test kits for the home.
Collection kits allow people to take a sample at home, e.g. B. saliva or a nasal swab, but you will need to send this sample to a designated laboratory for results.
With at-home test kits, you can wipe your nose and then smear the swab onto a preprocessed card to which you add a solution provided. The results appear in a matter of minutes, just like a pregnancy test. Some of these kits also come with a phone number for a telemedicine who can watch you sample and perform the test, and then verify the result with a digital certificate if requested by your employer or other organization. The completely self-made self-test kits do not offer such certification.
Can home tests identify the delta variant?
Currently available COVID-19 tests, including PCR tests, are designed to detect any version of SARS-CoV-2 and are not specific to different variants.
When should I do a home test?
Doctors and public health officials disagree on who should use rapid tests at home. The CDC recommends that workplaces, schools, or other organizations use rapid tests among people who are not vaccinatedto see if they are infected and could spread COVID-19.
However, many doctors only recommend them to people with symptoms like a runny nose, fever, or cough who want to know if they have COVID-19 or the flu (or any other respiratory infection). “These tests are best used to aid in diagnosing symptomatic COVID-19,” said Omai Garner, director of clinical microbiology for the University of California, Los Angeles Health System and director of point-of-care testing. “I keep a strong line here.”
It doesn’t support more routine testing in people with no symptoms because the more people do the tests, the greater the chance of false positives. This is especially true in areas with relatively high vaccination coverage and low disease prevalence. “Performing regular antigen tests on people with no symptoms in a low” [COVID-19] The prevalence setting really only demands false positive results, ”he says. “I don’t think they should be used for asymptomatic screening for any reason.”
Mina, on the other hand, points out that knowing the COVID-19 status of people due to asymptomatic screening can be useful for public health purposes in controlling the spread of the disease, especially since many people are infected with no symptoms demonstrate. As more students return to school, test kids could alert parents and schools before boarding the bus about when kids should stay home if they are infected. Mina also believes that rapid tests should be used at home before people enter workplaces, board a plane, or attend a sporting event, among other things. The idea is to quickly know who is infected and who is not, to make sure everyone is safe.
What about false positives on home tests?
No test, including the gold standard PCR tests, is 100% sensitive, so false positive and false negative results are always possible. (Ellume, an Australia-based manufacturer, recently called back 200,000 test kits following any of the components of the test produced inaccurate false positives.) But in general, the rate of false positives on home testing is relatively low, and Mina suggests an easy way to address this problem. If you get a positive result, try another test again; if it’s positive too, then it’s probably right.
Mina also points out that rapid tests have a different purpose than PCR testing. A PCR test is an important tool for the medical community – doctors and medical staff – to confirm whether someone is infected with SARs-CoV-2. Rapid home tests also identify infected people, but for a different, broader purpose – these tests are most useful for finding people who are infectious or contagious and should therefore not go out in public. The rapid antigen tests are more of a public health tool and so don’t have to do what the PCR does and pick up every scrap of SARS-CoV-2, including any residual, inactive virus from an old infection. It’s like the difference between a TSA agent at the airport asking each passenger to open their baggage and then inspect each bag by hand – the PCR standard – or scanning each bag through a detector – the fast antigen standard . Yes, the latter may miss some security breaches, but it will likely pick up on the most obvious ones.
Will states or the US government start paying for home testing?
The Biden government is committed to improving access to home testing. On October 6th, the New York Times reported that the White House plans to announce a $ 1 billion investment to make more home tests available, quadrupling the number of kits available to consumers by the end of the year.
To make testing more accessible, earlier this year The Biden administration urged retailers like Amazon, Walmart, and Kroger to sell home test kits at cost rather than for profit, which could save people about 35% of the current $ 25-30 cost per kit. Medicaid will also cover home testing, and the federal government will send 25 million test kits to 1,400 community health centers and boards across the country so more people can use their COVID-19 status.
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