Why COVID-19 testing at home may limit the way the United States tracks new cases
Why COVID-19 testing at home may limit the way the United States tracks new cases

Why COVID-19 testing at home may limit the way the United States tracks new cases

The majority of people in the United States who are testing positive for coronavirus right now are probably not included in official case counts, and this means that our understanding of current – or future – waves of the virus is weaker than it has been in the past.

In the week ending May 7, two positive COVID-19 laboratory tests were estimated for every fifth positive home test, which is largely unreported.

The crowdsourced data comes from Outbreaks Near Me, a website that collects voluntary information from individuals to identify COVID-19 hotspots through a partnership with Momentive
the company that owns SurveyMonkey.

“A few weeks ago, we had a shift where more people are now testing positive with the home tests than all the other tests combined,” said Dr. John Brownstein, an epidemiologist and chief innovation officer at Boston Children’s Hospital. (Outbreaks Near Me is a project that came out of his lab at the hospital.)

The widespread availability of home tests has been a good thing for Americans. Ever since the beginning of this year, when the Biden administration made home COVID-19 tests available free of charge to U.S. households, they have become a part of our daily lives. Boxes with BinaxNow and FlowFlex are stacked near the pharmacy’s box. A certain number of samples can be reimbursed by the insurance. And fewer people are waiting in long queues for a PCR test or days to get a result.

But there are drawbacks to these tests. Because there is no easy way to report results to local or state authorities, these data are not often included in official case reports, which are used to calculate positivity rates and can serve as an indicator of the amount of virus in a community.

“The more people start using these tests, the more it will create this further gap between what public health knows and is able to respond to and what is actually happening on the ground,” Brownstein said.

The number of new COVID-19 cases in New England is increasing, although many of these infections are not included in official cases because they were detected using home tests. Source: OutbreaksNearMe and Momentive

A new wave?

The number of new infections in the United States has doubled over the past month due to the spread of BA.2 and BA.2.12.1 Both sub-variants of omicron. The United States on Wednesday reported about 161,000 new cases, the largest number of new daily infections over the past three months and mainly driven by an increase in cases in the Northeast, according to New York Times case tracker.

“We are probably in the middle of a big increase,” said Dr. Michael Mina, a former epidemiologist at Harvard University who is now chief science officer at eMed, which links home testing to telecommunications services. “Right now we are seeing rates that are higher than any other time in the pandemic, with the exception of below the very, very, very high peak of the omicron.”

The United States first saw one signal in the wastewater monitoring that the COVID-19 cases were increasing around mid-March. Then the number of new infections begins to increase mid to late March. Hospital admissions, which tend to delay cases, recently began to tick up and have risen 20% over the past two weeks, according to the Times tracker. Death rates, which usually follow hospitalizations by a few weeks, are still low, with about 320 new deaths reported each day.

Mina, who has long been an advocate for home testing during the pandemic, now sees two issues with home testing.

Not only are the results not often included in official case counts, people who find that they have been tested positive for the virus are sometimes unclear what to do. They may wait to seek treatment until it is time to be admitted or miss the window to get the antiviral Paxlovid prescribed, which should be started within five days of symptoms.

“People just don’t act after their self-test, and they don’t report either, so it’s kind of a double-edged sword,” he said.

Other changes in how the US tests for COVID-19

The increasing use of home testing is one of the reasons why the official number of cases may not reflect a more accurate inventory of new infections, but there are several other factors affecting the perception of COVID-19 prevalence right now.

  • The government in March stopped paying for tests for uninsured Americansa decision that prompted Quest Diagnostics Inc.

    to start asking for payment in advance from these people. (“As a result, we have seen a decline in our uninsured COVID-19 molecular test volumes in late March and into April,” the CEO said recently.)

  • Most states have changed in the spring how often they report COVID-19 information, according to one Nature editor released in March. Washington, DC, has not reported infection data to the CDC for two weeks, according to the Washington Postand Florida now reports COVID-19 data every two weeks.

  • And finally, there is pandemic fatigue. Experts say some people are no longer worried about testing as local and state governments have lifted mask mandates and milder infections have been reported among those vaccinated and boosted.

So why does it matter?

Public health experts say there is an additional concern to consider: the United States uses samples collected from PCR tests to perform genomic monitoring of the virus. This is how we identify new varieties.

“We want gaps in our ability to see a new variant emerge here,” Brownstein said.

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