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Testing yourself for coronavirus infection can be more convenient than getting a clinic or lab test, but from a public health standpoint, experts say there’s at least one key downside.

Actual infection numbers in the United States in the first week of July were about seven times higher than reported cases, suggested an estimate from the Institute for Health Metrics and Evaluation. Contributing to the problem has been the steep spike in use of self-tests, which has surpassed the number being done in laboratories, according to the National Institutes of Health.

In the US, positive results of Covid-19 tests administered by medical professionals are ultimately reported to the US Centers for Disease Control and Prevention. But there isn’t any requirement for people to report their self-test results to health care providers or local public health departments.

Coronavirus self-tests – also known as home tests or over-the-counter tests – detect current coronavirus infections, not antibodies to the virus, and can easily and quickly be taken at home or elsewhere, regardless of your vaccination status, the CDC says. Most self-tests are rapid antigen tests, which can be less sensitive than PCR tests done in clinics or labs. Some home tests are PCR tests, but antigen versions are much more common and accessible.

An Easton, New Hampshire, resident prepares to take a Covid-19 self-test on December 7, 2021.

Ideally, you should report positive results to both your provider and local health department for several reasons, said Dr. Georges Benjamin, the executive director of the American Public Health Association. For one, he explained, if you test positive, your health care provider might need to intervene with treatments such as monoclonal antibodies or antivirals to mitigate your symptoms, depending on your Covid-19 vaccination or health status.

Reporting positive test results to your local public health department helps experts understand the prevalence of a new disease in different communities, he added.

“Presence of disease is an earlier indicator than the hospitalizations and can help us predict workforce needs, staffing needs for hospitals,” he added. “If you know you’ve got a community that hasn’t had a lot of infection and all of a sudden you’re seeing it grow, then you can usually predict that two or three weeks from then, they’re going to be seeing more cases in the hospital (and) tragically, death, too.

With the Omicron offshoot BA.5 becoming the dominant variant in the US earlier this month will come higher numbers of cases and hospitalizations, although apparently less severe, experts told CNN this month.

Awareness of positive self-test results can also help public health experts better understand how vaccines are holding up against the virus – and which activities might be particularly risky for getting Covid-19, said Dr. Jonathan Golob, an assistant professor of internal medicine in the Division of Infectious Diseases at the University of Michigan.

Knowledge of all these factors influences health experts’ recommendations, Benjamin said, including guidance on safety precautions and closures, mask mandates, and how the disease affects unvaccinated and vaccinated people differently.

“The best way to answer all of these critical questions we all have about the pandemic is through reporting of cases of COVID-19 to public health experts,” Golob said via email. “People at your local public health departments are experts at using case reports to figure out answers for these questions, working hand in hand with other scientists and doctors to make use of the case reports to adjust treatments, guidance and planning.”

Here’s how you can help.

Making calls

If you test positive for coronavirus, let your primary care doctor know by phone or email, Benjamin and Golob recommended. Some doctors will report your results to the local public health department, but it’s possible they won’t – which is why you should inform the health department, too, Benjamin said. Ultimately, if both you and your physician report your positive case to a health department, the health department should have enough information to avoid having duplicate details, he added.

Before contacting medical professionals, have a few key details readily available, Benjamin and Golob advised, including the type of test you took (rapid or regular antigen or PCR); when you took it; when symptoms started, if applicable; your vaccination status, which vaccine you received, when your doses were and whether you have received a booster shot; any details about over-the-counter medications you have taken to treat symptoms; and names of people and places you were near in the days leading up to your test result.

Some public health departments have apps or website tools for self-reporting, such as this online form for Ohio residents. And some self-tests, such as the BinaxNOW home test, have an option for trained telehealth providers to proctor the test and send the result to both you and relevant public health authorities.

As contact tracing experts, public health offices can help you figure out who else needs to know, as well as help you contact them in some cases, Golob said. The public health office won’t share your name with recent contacts. It will only inform those contacts of their potential or definite exposure, according to the CDC. Also, during contact tracing, the health department staff won’t ask for money, social security numbers, or banking, credit card or salary information.

If you choose to inform close contacts yourself, tell them they might have been exposed to coronavirus since, according to the CDC, a person with Covid-19 can begin spreading it 48 hours before any symptoms or a positive test result.

“It’s not 100% that all will get sick, but it can help people follow the suggestions of what to do after a close exposure to COVID-19,” Golob said. “If you were in a place like a school or workplace, it’s probably wise to loop them in too, and let them help you notify others of the possible exposure.”

The CDC also has a worksheet to help you determine what constitutes a close contact. If you prefer to anonymously inform your close contacts, there’s an online tool for that, endorsed by the CDC.

When reporting negative results is helpful

If you’re fully vaccinated and have recently been exposed to someone with Covid-19, you should take a test at least five days after the exposure, the CDC says.

If you’re unvaccinated and learn you’re a close contact, get tested immediately. Exposed and unvaccinated people who test negative should get tested again five to seven days after their last exposure or immediately if symptoms develop, according to the CDC.

If you test negative – or your result is invalid but you’re concerned or experiencing symptoms – still talk to your doctor in case they want to see you in person or have you get a PCR test to confirm whether you have Covid-19 or another infection, Benjamin said.

“If you are exposed to COVID, a negative test can be really helpful – particularly about three to five days after the exposure. A negative test then (or better yet two tests taken at least 24 hours apart) can reassure places like work or school you are less likely to transmit to others,” Golob said via email. “A negative home rapid antigen test taken right before a gathering can help reassure everyone involved that at that moment you are not shedding a lot of virus.”

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“Like the vaccines, masks, antibody treatments, antiviral medicines, COVID-19 tests are an amazing invention to help us all fight back against the virus,” Golob said. “After two years I am, like most of you, ready to get back to some life. I’m vaccinated and boosted. I wear a mask in public. I use COVID-19 tests (including home rapid antigen tests) before visiting with others. All together, these tools help me get back to life.”

CNN’s Jen Christensen, Jamie Gumbrecht, Jacqueline Howard and Deidre McPhillips contributed to this story.