Skip to content
  • About
  • Contact
  • Contribute
  • Book
  • Careers
  • Podcast
  • Recommended
  • Speaking
  • All
  • Physician
  • Practice
  • Policy
  • Finance
  • Conditions
  • .edu
  • Patient
  • Meds
  • Tech
  • Social
  • Video
    • All
    • Physician
    • Practice
    • Policy
    • Finance
    • Conditions
    • .edu
    • Patient
    • Meds
    • Tech
    • Social
    • Video
    • About
    • Contact
    • Contribute
    • Book
    • Careers
    • Podcast
    • Recommended
    • Speaking

Who should we really be testing for COVID-19?

Michael Wolfson, PhD
Conditions
May 5, 2020
Share
Tweet
Share

The Canadian federal government recently announced it would fund at least one million blood tests to track the novel coronavirus over the next two years.  This is a step in the right direction.  But is it enough?

How do we know if we are testing the right number, and the right people, especially as the pressure to ease up on the lockdown and isolation rules increases?  The answer depends critically on why we need test results.

A sophisticated sampling strategy is the only path forward at present.  There simply are not enough resources to test every one or even perform a simple random sample.

Perhaps half of those infected do not show more than very mild symptoms, if any. These individuals have greatly complicated efforts at epidemic control.  If everyone infected with COVID-19 had symptoms, we could simply require them to self-isolate. Instead, we have to keep two meters from everyone and wear masks, because we cannot tell if they are infected but not showing it.

Public health agencies clearly need to continue and expand testing for high-risk populations, including front-line health care workers, personal support workers (PSWs) working in nursing homes, retirement residences and in home care, as well as the public health workers doing contact tracing.

But we need to do better, with reliable real-time data on how many people in the population are, or have been, infected and where they are.  Tests of current infections, with a lag of a few weeks, signal impending hospitalizations. That’s no longer good enough.

It is essential to detect and isolate infected individuals quickly, and as many of their contacts as can be traced, if we want to relax the restrictions as quickly as possible.

Blood tests, as the government has just announced, can tell us how many people have been infected (though the amount of resulting immunity remains unknown).  But these will likely be far below those needed for herd immunity, so low that significant relaxation of physical distancing would result in a surge of new infections — straining health care resources, causing more deaths, and requiring the reintroduction of draconian controls.

To monitor adequately, the tests cannot cover only symptomatic individuals since this will miss the large asymptomatic or pre-symptomatic portion of the infected population.

It matters who is tested.  If it’s mainly individuals who live alone and are careful about physically isolating, most tests will be negative.  For PSWs or meat processing plant workers, though, the same number of tests could find much higher rates of infection.

To provide valid and useful results, testing needs to be based on sophisticated sampling, simple random samples will not work.  A highly controversial Santa Clara study of how many residents have been infected shows the perils of poor sampling.

For example, nursing homes need their own samples; indeed, every resident should be tested periodically for the time being.  For the general population, though, a multi-pronged effort is needed, starting with new clusters of infection, including key groups such as front-line workers in shops that are re-opening.

We also need to distinguish geographic regions within provinces, for example, different cities.  Even though most of the public discussion has been about policies at the provincial level (and state level in the U.S.), proper sampling, and relaxation policies, will need to target very real differences within provinces.

ADVERTISEMENT

In sum, we need a sophisticated sampling strategy for testing, and one that can adapt to evolving circumstances, not least as physical distancing and related policies are reduced.

These data need to be accessible for statistical analysis not only locally, not only provincially, but also nationally, and of course, they need to be securely handled and protected.

Testing results, based on proper and extensive sampling, are fundamental to improving the model results shown on TV and used by governments to inform the relaxation of restrictions.  This would allow us to return to a new normal – more quickly, and with lower risks of serious mistakes.

Michael Wolfson is a statistician.

Image credit: Shutterstock.com

Prev

Vulnerability is challenging but necessary for health care professionals

May 5, 2020 Kevin 0
…
Next

The exacerbation of social isolation among the elderly

May 5, 2020 Kevin 1
…

Tagged as: COVID, Infectious Disease, Public Health & Policy

Post navigation

< Previous Post
Vulnerability is challenging but necessary for health care professionals
Next Post >
The exacerbation of social isolation among the elderly

ADVERTISEMENT

Related Posts

  • A patient’s COVID-19 reflections

    Michele Luckenbaugh
  • COVID-19 shows why we need health insurance

    Jingyi Liu, MD
  • How to get patients vaccinated against COVID-19 [PODCAST]

    The Podcast by KevinMD
  • COVID-19 divides and conquers

    Michele Luckenbaugh
  • State sanctioned executions in the age of COVID-19

    Kasey Johnson, DO
  • Starting medical school in the midst of COVID-19

    Horacio Romero Castillo

More in Conditions

  • How veteran health care is being transformed by tech and teamwork

    Deborah Lafer Scher
  • What Elon Musk and Diddy reveal about the price of power

    Osmund Agbo, MD
  • Understanding depression beyond biology: the power of therapy and meaning

    Maire Daugharty, MD
  • Why medicine must stop worshipping burnout and start valuing humanity

    Sarah White, APRN
  • Why perinatal mental health is the top cause of maternal death in the U.S.

    Sheila Noon
  • A world without vaccines: What history teaches us about public health

    Drew Remignanti, MD, MPH
  • Most Popular

  • Past Week

    • Why are medical students turning away from primary care? [PODCAST]

      The Podcast by KevinMD | Podcast
    • Why “do no harm” might be harming modern medicine

      Sabooh S. Mubbashar, MD | Physician
    • How New Mexico became a malpractice lawsuit hotspot

      Patrick Hudson, MD | Physician
    • Why doctors are reclaiming control from burnout culture

      Maureen Gibbons, MD | Physician
    • Why health care leaders fail at execution—and how to fix it

      Dave Cummings, RN | Policy
    • How veteran health care is being transformed by tech and teamwork

      Deborah Lafer Scher | Conditions
  • Past 6 Months

    • Why tracking cognitive load could save doctors and patients

      Hiba Fatima Hamid | Education
    • Why are medical students turning away from primary care? [PODCAST]

      The Podcast by KevinMD | Podcast
    • What the world must learn from the life and death of Hind Rajab

      Saba Qaiser, RN | Conditions
    • Why “do no harm” might be harming modern medicine

      Sabooh S. Mubbashar, MD | Physician
    • Here’s what providers really need in a modern EHR

      Laura Kohlhagen, MD, MBA | Tech
    • Why flashy AI tools won’t fix health care without real infrastructure

      David Carmouche, MD | Tech
  • Recent Posts

    • How veteran health care is being transformed by tech and teamwork

      Deborah Lafer Scher | Conditions
    • Why judgment is hurting doctors—and how mindfulness can heal

      Jessie Mahoney, MD | Physician
    • Why medical schools must ditch lectures and embrace active learning

      Arlen Meyers, MD, MBA | Education
    • Why helping people means more than getting an MD

      Vaishali Jha | Education
    • How digital tools are reshaping the doctor-patient relationship

      Vineet Vishwanath | Tech
    • Why evidence-based management may be an effective strategy for stronger health care leadership and equity

      Olumuyiwa Bamgbade, MD | Physician

Subscribe to KevinMD and never miss a story!

Get free updates delivered free to your inbox.


Find jobs at
Careers by KevinMD.com

Search thousands of physician, PA, NP, and CRNA jobs now.

Learn more

Leave a Comment

Founded in 2004 by Kevin Pho, MD, KevinMD.com is the web’s leading platform where physicians, advanced practitioners, nurses, medical students, and patients share their insight and tell their stories.

Social

  • Like on Facebook
  • Follow on Twitter
  • Connect on Linkedin
  • Subscribe on Youtube
  • Instagram

ADVERTISEMENT

  • Most Popular

  • Past Week

    • Why are medical students turning away from primary care? [PODCAST]

      The Podcast by KevinMD | Podcast
    • Why “do no harm” might be harming modern medicine

      Sabooh S. Mubbashar, MD | Physician
    • How New Mexico became a malpractice lawsuit hotspot

      Patrick Hudson, MD | Physician
    • Why doctors are reclaiming control from burnout culture

      Maureen Gibbons, MD | Physician
    • Why health care leaders fail at execution—and how to fix it

      Dave Cummings, RN | Policy
    • How veteran health care is being transformed by tech and teamwork

      Deborah Lafer Scher | Conditions
  • Past 6 Months

    • Why tracking cognitive load could save doctors and patients

      Hiba Fatima Hamid | Education
    • Why are medical students turning away from primary care? [PODCAST]

      The Podcast by KevinMD | Podcast
    • What the world must learn from the life and death of Hind Rajab

      Saba Qaiser, RN | Conditions
    • Why “do no harm” might be harming modern medicine

      Sabooh S. Mubbashar, MD | Physician
    • Here’s what providers really need in a modern EHR

      Laura Kohlhagen, MD, MBA | Tech
    • Why flashy AI tools won’t fix health care without real infrastructure

      David Carmouche, MD | Tech
  • Recent Posts

    • How veteran health care is being transformed by tech and teamwork

      Deborah Lafer Scher | Conditions
    • Why judgment is hurting doctors—and how mindfulness can heal

      Jessie Mahoney, MD | Physician
    • Why medical schools must ditch lectures and embrace active learning

      Arlen Meyers, MD, MBA | Education
    • Why helping people means more than getting an MD

      Vaishali Jha | Education
    • How digital tools are reshaping the doctor-patient relationship

      Vineet Vishwanath | Tech
    • Why evidence-based management may be an effective strategy for stronger health care leadership and equity

      Olumuyiwa Bamgbade, MD | Physician

MedPage Today Professional

An Everyday Health Property Medpage Today
  • Terms of Use | Disclaimer
  • Privacy Policy
  • DMCA Policy
All Content © KevinMD, LLC
Site by Outthink Group

Leave a Comment

Comments are moderated before they are published. Please read the comment policy.

Loading Comments...