November 5, 2020

It's getting harder to tell how Americans are catching the coronavirus

Daily Briefing

    Amid a surge in novel coronavirus cases nationwide, it's getting harder for public health officials to get an accurate count of how many Americans have been infected with the virus—and to pinpoint how Americans contracted the pathogen, the New York Times reports.

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    It's getting harder to track how many Americans have been infected, experts say

    Currently, the two most commonly used types of coronavirus tests in America are polymerase chain reaction (PCR) tests and antigen tests. Antigen tests produce results faster than PCR tests, but they're less likely to detect lower levels of the novel coronavirus.

    Because the antigen tests may miss people with lower levels of the virus, some states do not include positive antigen tests in their official coronavirus case counts—though that conflicts with current CDC guidance on case reporting, the Times reports. According to the Times, seven states and Washington, D.C., don't include positive antigen tests in their official case counts, and six states separate positive antigen tests from positive PCR tests in their total reported case counts.

    As it stands, the portion of Americans who test positive with antigen tests is relatively small, the Times reports. In Florida, for example, positive antigen tests make up about 4% of all cases the state has reported since March, according to the Times.

    However, antigen testing for the novel coronavirus is likely to become more common, as the federal government has purchased antigen tests intended for use in schools and nursing homes this fall. In addition, some companies are hoping to get federal approval to make their tests available over the counter for Americans to use on their own at home.

    Some experts say states' decisions not to report positive antigen tests in their total case counts can provide a false sense that coronavirus cases infection rates are lower than they actually are.

    For instance, Annie Drachenberg, medical director for Abilene-Taylor County Health District in Texas, said that positive antigen tests account for more than half of all coronavirus cases reported in Taylor County.

    Lisa Dick, administrator of the Brownwood-Brown County Health Department in Texas, said, "If we just posted PCR tests we would just be giving the community the idea that things were improving. … And people are making decisions based on that information, from leaders to individuals."

    And many public health officials say that, even if states do report positive antigen tests results for the novel coronavirus, they can't be sure providers always are reporting the test results. They explained that the tests can be used at various point-of-care centers, including nursing homes and urgent care centers, and some of those centers may be unaware that they need to report the results.

    "We don't know for sure what we don't know," Edward Lifshitz, medical director for the Communicable Disease Service at the New Jersey Department of Health, said.

    Further, experts have estimated that, as antigen tests become more available and potentially are approved for at-home use, the true number of coronavirus cases in America may become almost impossible to track, the Times reports.

    "We may eventually get these tests over the counter," Lifshitz said. "From a public health perspective that's a good thing. From a surveillance perspective, that becomes a nightmare."

    It's also getting harder to pinpoint how Americans contracted the coronavirus, experts say

    Another key to tracking coronavirus cases is contact tracing—an effort through which public health officials try to trace the virus's transmission from person-to-person, in hopes of encouraging testing and measures to mitigate the virus's further spread. But as new cases of the coronavirus have surged throughout the United States in recent weeks, Americans have become less sure of where they may have contracted the coronavirus, the Times reports.

    For example, Denny Taylor, 45, told the Times that even though he had taken precautions including wearing a mask and having his groceries delivered, he became the first person among his family and co-workers to test positive for the virus. "I was so careful," Taylor said, adding that he had no idea of how he contracted the virus.

    Likewise, Heidi Stevens, a columnist at the Chicago Tribune, recently tested positive for the novel coronavirus, despite the fact that she works from home, her children attend school online, and she wears a mask while she's out. Stevens also has said she has no idea how she caught the virus.

    "I would drive myself crazy if I tried to really nail it down," she said. "It's just out there."

    Crystal Watson, a senior scholar at the Center for Health Security at the Johns Hopkins Bloomberg School of Public Health, expressed a similar sentiment. The coronavirus is "just kind of everywhere," she said.

    As a result, some health officials have said contact tracing won't be enough to slow the rise in new cases, and some states have announced that they'll no longer be performing contact tracing to the extent they were earlier this year.

    For example, in North Dakota, officials have announced they won't have one-on-one conversations with every person that officials identify who may have been exposed to the virus. And in Philadelphia, officials have acknowledged that some coronavirus cases won't be tracked.

    "We weren't supposed to get to this point," Arnold Monto, a professor of epidemiology at the University of Michigan, said. He said that although tracking cases and notifying those who may have been exposed to the virus is a best practice to mitigate further transmission, it's not practical after a certain number of cases. "If you have five clusters going on at the same time, it's hard to say where it came from."

    Watson said that tracing coronavirus cases becomes harder once more than 10 in 100,000 people have the virus—and, according to the Times, the novel coronavirus is "spreading at 10 to 20 times that rate" in some areas of the country.

    Ultimately, at this point, "[c]ontact tracing is not going to save us," Ogechika Alozie, CMO at Del Sol Medical Center, said (Mervosh/Tompkins, New York Times, 10/31; Walker/Patel, New York Times, 11/1).

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