Can You Save the Second Test in a COVID-19 Test Kit?

at-home covid test

Verywell Health / Dennis Madamba

Key Takeaways

  • Many COVID-19 test kits come with two tests inside because testing twice within a matter of days increases the chance of getting an accurate result.
  • You should use the second test to confirm a negative result after a COVID-19 exposure or to check if you’re still infectious after testing positive.
  • If you have symptoms and you tested negative, you can also opt for an PCR test instead, which is more sensitive.

Frequent testing is crucial in reducing the spread of COVID-19. And now that free at-home COVID-19 tests are available from the government, more people have access to tests when they need them.

But those kits come with two tests inside the package. Although the instructions say that you are supposed to take both tests a few days apart, some people save the second one for a much later date.

So when should you be taking that second test and when is it OK to save it?

Why Do Test Kits Come With Two Tests Inside?

Why are two tests included in some kits anyway?

“Some rapid antigen test kits may come with two tests inside because testing consistently over the course of a few days increases your chance of getting a more accurate result,” Jay W. Lee, MD, MPH, family physician and chief medical officer of Share Our Selves Community Health Center, told Verywell.

A study published in The Journal of Infectious Diseases reported that testing multiple times a week increases the sensitivity of antigen tests due to the different stages of infection. Both rapid antigen and polymer chain reaction (PCR) tests were found to have greater than 98% sensitivity in detecting COVID-19 if used at least every three days. 

“A person’s viral load can increase extremely quickly, making rapid tests best used consecutively or repeatedly over the course of a couple of days,” Lee said.

What This Means For You

It’s important to use the second test in the kit if you’re testing after a potential COVID-19 exposure or you are experiencing symptoms. If you tested negative with the first test, use the second a few days later to verify the result. If you tested positive, you can use the second test to see when you can safely return to school or work.

When Should You Use the Second Test?

It’s OK to use just one test if you are testing before attending an event or a gathering, but if you were exposed and want to test a few days after, that’s where two tests come in handy, Gigi Gronvall, PhD, senior scholar at the Johns Hopkins Center for Health Security at the Bloomberg School of Public Health, told Verywell.

The second test is also helpful if you're gauging whether you should end isolation.

To Check If You Have COVID-19 After Exposure

Being in close contact with someone who turned out to have COVID-19 means you may have been infected as well.

“If you know you were exposed on a Saturday, testing three and five days after would be a good idea,” Gronvall said. “Three days might be too early, in which case you have the second test to try on day five.”

It’s important to test for a second time after being exposed to COVID-19 because it’s possible that you didn’t have a sufficient viral load the first time you tested, which can result in a false negative.

If you tested negative but you are experiencing symptoms, you may want to use the second test about 24 to 36 hours later to see if you get a positive result, Gronvall noted. 

To Check If You’re Infectious After Testing Positive

If you tested positive—whether you tested after a potential COVID-19 exposure or because you’re suddenly experiencing symptoms—you need to isolate for at least five days. Afterward, it’s best to use another test before resuming your normal activities.

“It is recommended that you test again five to seven days after the onset of symptoms and without symptoms for at least 24 hours to determine whether you're outside the window for risk of infecting others,” Lee said. “In some cases, patients have remained persistently positive beyond that timeframe, so it's not always a slam dunk that you'll be negative even after the five- to seven-day window.”

Testing for a second time minimizes the risk of leaving isolation while you’re still contagious.

“Once symptoms have resolved, the second rapid test could be best used to determine when it would be safe for an individual to return to work or school,” Lee said. “It isn't always the case that the presence or absence of symptoms is the best way to determine whether someone is at low risk of spreading COVID-19.”

In some cases, you might opt for a PCR test instead of a rapid antigen test, which is less likely to produce a false negative result. The Centers for Disease Control and Prevention (CDC) recommends that negative antigen test results in symptomatic individuals be verified with an PCR test.

PCR tests are much more sensitive at picking up the COVID-19 virus and are considered the gold standard for diagnosis,” Lee said. “If your first rapid antigen test was negative and you still have symptoms, I would advise you to get RT-PCR tested as it is more likely to detect COVID-19 at lower levels.”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Smith RL, Gibson LL, Martinez PP, et al. Longitudinal assessment of diagnostic test performance over the course of acute SARS-CoV-2 infection. The Journal of Infectious Diseases. 2021;224(6):976–982. doi:10.1093/infdis/jiab337

  2. Centers for Disease Control and Prevention. Quarantine and isolation.

  3. Brihn A, Chang J, OYong K, et al. Diagnostic performance of an antigen test with RT-PCR for the detection of SARS-CoV-2 in a hospital setting — Los Angeles County, California, June–August 2020. MMWR Morb Mortal Wkly Rep. 2021;70:702–706. doi:10.15585/mmwr.mm7019a3

By Carla Delgado
Carla M. Delgado is a health and culture writer based in the Philippines.