LOS ANGELES – Even with vaccinations on the rise, some health officials fear large gatherings this holiday season could lead to major outbreaks of COVID-19. But families looking to reunite have at least one infection prevention tool they didn’t have last year: rapid home testing kits.
The kits are not reliable, and most are not as reliable as laboratory alternatives when it comes to detecting infections in the earliest stages. Also, the cost can be high if you need to check a house full of people.
However, under the right circumstances, a home test can alert you in minutes if Cousin Antoine’s cough or Aunt Maggie’s muscle aches are signs of a potentially serious threat to the rest of the family. What’s more, tests can make it easier for your invited guests to check for active infection before they leave for your home.
Another important caveat: if you haven’t received your full vaccinations, the Centers for Disease Control and Prevention cautions against traveling to this holiday event. And if you are determined to travel without vaccinations, the CDC recommends that you only do so if you get a negative COVID test one to three days before departure and then quarantined for seven days after arrival (or less if you get negative again).
Here’s a rundown of how the tests work, how reliable the results are, who makes them, where to find them, and how much they cost.
What are Home Rapid COVID Tests?
The key word here is “fast”, as the result is achieved in about 15 minutes. Unlike self test kits, which you have to send to the lab for processing, rapid test kits allow you to process samples at home – in fact, most of them allow you to watch the results slowly appear on the test strip just like you could watch the shape of the image on a polaroid (but with higher rates).
The US Food and Drug Administration has issued an emergency permit for two types of rapid tests: molecular and antigenic. Molecular tests, which are more sensitive but require a higher cost, examine the genetic material in your sample for the SARS-CoV-2 virus. Antigen tests check for the presence of a protein that binds to the RNA of the coronavirus.
Only one of three approved in-house molecular tests – the Lucira CHECK-IT kit – is easy to find on the Internet, and it’s expensive: Amazon sells it for $ 89 per test.
On the other hand, a quick search for antigen tests yielded six of the nine approved tests available to consumers in the US in stores or online, one from two different manufacturers:
– iHealth – $ 14 for a pack of two on the company’s website.
– QuickVue – $ 20 to $ 24 per pack of two at local pharmacies.
– BinaxNow – About $ 24 per pack of two at local pharmacies.
– CareStart – $ 24 per package of two at RiteAid.
– BD Veritor – $ 26.50 per two-pack at Amazon.
– Inteliswab – $ 29 to $ 40 per pack of two at online health stores.
– On / Go – $ 35 per pack of two at Amazon, Walmart, and the company’s website.
Another Celltrion antigen test is available in large quantities at online medical supply stores for about $ 10 per test.
Different antigen test kits have different functions – for example, some have smartphone apps that can display the test result, which would be helpful if you are asked to provide proof of a negative test result. And the test results may vary, although they all went well enough to get FDA clearance for emergency treatment.
Dr. Ashish Q. Jha, Dean of the School of Public Health at Brown University, said the BinaxNow test was the most widely used test and therefore has more results than other tests. But he said people shouldn’t pay too much attention to brands, given that there were relatively few tests. “Any of the tests you can find are much better than no tests,” he said.
How reliable are the results?
The coronavirus, which causes COVID-19, can take days to build up steam (or “viral load”), which means you are unlikely to develop symptoms or become infected immediately after infection. This is why public health officials advise you not to get tested immediately after coming into contact with people who may be infectious.
Molecular tests, however, use chemical methods to increase the amount of genetic material in a sample, allowing them to detect the presence of coronavirus at a very early stage – in some cases even before a person can transmit the infection to others. On the other hand, they can also find the remaining traces of the virus after the person is no longer infectious. And like any test, they are prone to contamination and other glitches that can lead to erroneous results, including random false positives. This is uncommon, but more likely to occur in communities where there are few cases of the disease.
It has been proven that antigen tests are no worse than molecular tests to avoid false positive results. And, according to the CDC, these tests are also good when it comes to detecting COVID in a person who is showing symptoms of the disease, such as cough, fever, and sore throat.
The CDC warns that tests fail when people have the virus but have no symptoms, especially if they are in the early stages of infection and do not yet have enough viral load to infect others. The agency recommends that people do a second antigen test a few days after the first, so the kits are sold in two packs.
If you have not been vaccinated and have had close contact with someone with COVID in the past two weeks, the CDC recommends getting a molecular test to make sure you are not infected.
What’s the best way to use rapid tests?
Testing can reduce risk in various holiday scenarios, but Jha and Dr. Robert Wachter, chair of medicine at UC San Francisco School of Medicine, said it makes the most sense in two situations: if unvaccinated people join in. you for the holidays, or if people in your group are at high risk of fatal complications if they contract the serious COVID-19 disease. “On top of that, while it might make the meeting a little safer, I don’t feel like I should spend a few hundred dollars testing 10 or so people,” Wachter said in an email.
Another factor affecting testing is the high rate of COVID infection in the community, Jha said. But which community determines the degree of risk? This can be tricky if you have guests from different parts of the country.
When and how often you should take the test depends on the nature of the meeting. “Rapid tests are a measure of infectivity,” Jah said, “and that’s why you want to test your interactions with people as accurately as possible.” If it’s just Thanksgiving lunch, Jha said, “the ideal situation would be to do the test on Thursday morning.”
But if this is a weekend visit, he and Wachter have offered to get tested more than once – say, just before arrival and again in a day or two – especially if you are in the presence of unvaccinated people. “Two negative tests, you are really ready to take,” Jha said, adding that if you are around people at high risk for COVID complications, you may even be tested daily.
“For the unvaccinated population, one test is probably not enough,” Jha said. As evidence, he pointed to a ceremony President Trump held last year for new Supreme Court Justice Amy Connie Barrett. Participants had to test negative in order to gain admission, but it still morphed into something akin to a super chairman.
How do you test yourself?
The typical process begins by taking a sterile swab from the kit and tracing the inside of each nostril multiple times. This collects a sample. The next step depends on the type of test.
In molecular tests, a swab is placed in a small container where the sample is mixed with a reagent, a substance that triggers the process of identifying the genetic makeup of the sample. The container is then placed in the base unit where the magic happens (technically isothermal amplification). The results are displayed on the base unit or in the smartphone app.
For antigen testing, a swab is placed in a disposable reader (often made of paper) where it meets the test strip. You add a few drops of the kit reagent, then watch to see if the strip is positive, negative, or inconclusive.
Be sure to read and follow the instructions carefully to collect a proper sample and avoid contamination. For example, with the popular BinaxNow test, you must rub each nostril for 15 seconds and rotate the swab three times after placing it in the reagent.