You have an at-home COVID-19 test kit—now what?
Connecticut towns and cities have begun distributing thousands of at-home COVID-19 testing kits to residents and essential workers. State and local officials say their overall goal is to increase access to testing as transmission continues to grow and businesses, schools and other operations remain open.
But demand continues to outpace the availability of test kits and in-person appointments as the state’s positivity rate climbs, reaching a record 24% as of Tuesday.
For those who have been able to get their hands on at-home tests, experts provide some guidance on how they can be used in a smart and effective way.
Antigen at-home tests vs. molecular in-person testing
A majority of the at-home or over-the-counter tests are rapid antigen tests that come in the form of nasal swabs, and they take about 15 to 30 minutes for results.
The tests are best at detecting COVID-19 when someone has a high viral load, or when there is a significant amount of virus in the body and a person can be more contagious.
“Depending if it’s in the very early stage or once you develop symptoms or after you develop symptoms, that viral load fluctuates, it changes over time,” said Dr. Enrique Ballesteros, chair of the department of pathology and laboratory medicine at UConn Health. “But the antigen test will be positive when the individual has a high viral load.”
It’s different from molecular tests like polymerase chain reaction (PCR) tests, which Ballesteros said are still considered the “gold standard” of COVID-19 testing. That’s because PCR tests are more sensitive, meaning they can detect even the smallest amounts of virus in a person’s body at many stages of infection.
However, PCR tests are largely done in person at clinical sites and require laboratory analysis. Currently, appointments for these tests are difficult to find, and the turnaround time for results can take several days.
“They both serve a purpose, they’re good tests,” Ballesteros said.
Why use an at-home test?
At-home antigen tests can quickly confirm COVID-19 infection in a symptomatic person and help narrow down a diagnosis at a time when other viruses, like the flu and respiratory syncytial virus (RSV), are also circulating.
They can also be used by asymptomatic people as a risk-reduction tool. The U.S. Centers for Disease Control and Prevent recommends using a self-test before joining indoor gatherings with people outside the household – experts say it’s best to do a test as close as possible to the time of the actual event.
The tests are also suggested for people who believe they may have been exposed to the virus by recent contact with an infected person.
In the latter two situations, serial testing, or doing two or more tests over several days, may be needed to ensure the most accurate results “so that, again, you increase the confidence that you are not infected,” said Anu Maharjan, clinical chemist and co-medical director of the Core Laboratory at UConn Health.
For people who don’t have access to multiple tests or who can’t immediately confirm the status of their infection, the CDC has updated guidelines on isolation and quarantine periods for symptomatic and asymptomatic people, depending on their vaccination status.
To make the greatest use of any at-home tests someone may have, public health experts say that will come down to individual circumstances – the necessity to attend certain events, working environment and related requirements, the presence of symptoms, known exposures and more.
As far as timing, Ballesteros said there is a window where antigen tests will most accurately detect COVID-19. But knowing the beginning and end points to that window is the tricky part.
“It’s during those initial symptoms – someone has a runny nose – that window right there is optimal for the antigen test to pick up,” he said. Even so, the presence of symptoms does not always coincide with high viral load, he added.
“There’s a little variation there,” Ballesteros said, when someone who is unknowingly infected and asymptomatic could transmit the virus to others.
How to use your test kit
Maharjan and Ballesteros said the most important thing for people to do is to carefully read the instructions that come with the test kits.
“So, for example, the self-collection,” Ballesteros said. “That swabbing, follow to the letter. And hopefully the manufacturer, the vendor, the company, whoever you’re getting the kit from, has provided user-friendly instructions so everybody can follow.”
Maharjan recommends people consult the U.S. Food and Drug Administration’s list of authorized at-home tests and manufacturers. Many of the home tests are similar in what they require and how they’re done.
“You want to perform the test in an environment where you have a space for it, where you are being as clean as possible,” she said.
Reviewing the instructions can help people avoid “user errors” and mistakes that could lead to a false positive or negative result, or an invalid test.
“You can have the most robust and most incredible instrument, the most incredible box with the latest technology, but if you have a bad specimen to start off with, there’s nothing you can do,” Ballesteros said.
Antigen tests and the omicron variant
Experts say COVID-19 tests are supposed to detect different variants of SARS-CoV-2, the virus that causes COVID-19.
The omicron variant is fueling the latest surge of COVID-19 outbreaks in Connecticut and the U.S. as the delta variant continues to cause new infections and hospitalizations.
“But there has been concern about omicron, especially because omicron is a highly mutated variant,” Maharjan said.
The FDA, in collaboration with the National Institutes of Health, is studying the performance of antigen tests with the omicron variant. In a Dec. 28 statement, the FDA said early data “suggests that antigen tests do detect the omicron variant, but may have reduced sensitivity.”
Interpreting your results
Positive people should follow the latest quarantine and isolation guidelines. Local health departments and the state Department of Public Health say that people who get a positive at-home test result do not need to get another test for confirmation.
However, people who test positive at home should check with their employer to confirm if a follow-up PCR test will be required documentation in order to qualify for paid COVID sick leave. A PCR test may also be required by health insurers, in order to prove treatment is needed for a potential case of "long COVID," which can last weeks or months.
Residents are not required to report their positive at-home results to state or local health authorities, but DPH recommends notifying places of work, schools or child care centers and close contacts.
Experts also suggest people notify their regular health care provider of any positive results.
“And let’s say you test negative, that means that the test did not detect the virus. It doesn’t mean you can rule out infection, so that’s why the repeat testing is important,” Maharjan said. “And as for someone who tests negative, but has a high suspicion that they have COVID-19, performing a molecular test is important to be able to discriminate if the person has COVID-19 or not.”