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Jan. 24 marks the one-year anniversary of a momentous but largely unnoticed event in the history of the Covid-19 pandemic: the first published report of an individual infected with the novel coronavirus who never developed symptoms. This early confirmation of asymptomatic infection should have set off alarm bells and profoundly altered our response to the gathering storm. But it did not. One year later we are still paying the price for this catastrophic blunder.

At least one of three people infected with SARS-CoV-2, the virus that causes Covid-19, do not develop symptoms. That’s the conclusion of a review we just published in the Annals of Internal Medicine. It summarizes the results of 61 studies with more than 1.8 million people.


But during much of the pandemic, fierce resistance — and even outright denialism — in acknowledging this not-so-typical disease pattern led to ineffective testing practices that allowed the pandemic to spin out of control.

On Jan. 28, 2020, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said, “In all the history of respiratory-borne viruses of any type, asymptomatic transmission has never been the driver of outbreaks. … Even if there’s a rare asymptomatic person that might transmit, an epidemic is not driven by asymptomatic carriers.”

This was a widely held view. On June 8, 2020, a senior official of the World Health Organization called asymptomatic transmission “very rare.”


To his credit, Fauci was among those who immediately criticized this remark. Based on epidemiological data that had become available since his earlier comments, he said it was “not correct” to characterize asymptomatic transmission as rare.

In June, when we published a report of 16 cohorts with sizable proportions of asymptomatic infection and suggested that it might play a role in the progression of the pandemic, several researchers wrote letters to the editor demanding that our paper be retracted.

Today, the best evidence suggests that about half of Covid-19 cases are caused by infected people who do not have symptoms when they pass on the virus. These symptom-free spreaders are roughly divided between those who later develop symptoms, known as pre-symptomatic individuals, and those who never develop symptoms.

While the importance of asymptomatic infection in understanding Covid-19 has been surprising to some, infectious disease experts have long known that infection without symptoms is common in many illnesses. More than 90% of people infected with poliovirus have no symptoms. And about 75% of influenza infections have been estimated to be asymptomatic. Yet these important precedents have largely been ignored.

Asymptomatic coronavirus infection is not necessarily benign. Several studies have reported abnormal lung scans in those infected without symptoms, as well as myocarditis, a type of heart inflammation. The long-term health implications of asymptomatic infection aren’t known.

Even though knowledge about asymptomatic infection has greatly evolved, tactics for combating the pandemic have not. It is now obvious that testing only those with symptoms, as was common early in the pandemic, is a mistake because it ignores the invisible legions of infected people who have no symptoms. But it is not enough to merely increase the number of tests. The problem is that current testing practices are ill-suited to detecting and containing asymptomatic infection.

Virtually all of the coronavirus testing performed in the U.S. looks for the genetic material of the virus using the polymerase chain reaction (PCR). It requires expensive equipment and trained technicians. Results are typically returned days — sometimes even weeks — after the test. That means people learn they have been infected with SARS-CoV-2 long after they may have passed the virus to others. Testing becomes more about accounting — tallying the number of detected infections — than about containing the spread of the virus.

What’s needed is a pivot to a different type of testing. Antigen tests, which look for a bit of coronavirus protein, cost just a few dollars each and can yield results in minutes. Like home pregnancy tests, they require minimal instruction. Antigen tests are ideal for spotting people who are infectious, rather than those who may be long past the infectious phase of Covid-19, or who harbor such low levels of the virus that they are unlikely to infect others.

Inexpensive rapid home tests would help infected people isolate themselves before they could spread the virus. Frequent testing — at least several times per week — is essential, as demonstrated by successful testing efforts at some universities, which have enabled students to return to campus. A new focus on self testing, in combination with financial assistance and perhaps even temporary housing for isolation, would directly address the problem of asymptomatic infection.

The rollout of Covid-19 vaccines brings with it the risk of a new wave of asymptomatic infections. The two vaccines authorized by the Food and Drug Administration have been proven to prevent illness, but not asymptomatic infection. Even after vaccination, the coronavirus may still temporarily take up residence in the lining of the respiratory tract, making it possible to infect others. Preliminary results from one vaccine trial seem encouraging, with an apparent two-thirds reduction in asymptomatic infection after the first dose. But many other studies are underway.

There is no time machine that would allow us to return to Jan. 24, 2020, and make the plans we should have made, which would have acknowledged the importance of asymptomatic infection. But it is not too late to recognize the blunder and move aggressively toward testing practices that will help end the pandemic.

Daniel P. Oran is a member of the digital medicine group at Scripps Research Translational Institute, of which Eric J. Topol is founder and director.

  • This is classic Monday morning quarterbacking to sound smart. The virus spread to every continent no matter what the protocol was. There are some thing that humans cannot control. This is one of them.

  • I’m 60 years old, I’ve had 5 heart attacks (4 stent implants) and a pericardial window. I’m also a diabetic type II and have high blood pressure. I’m very nervous when out in public due to the virus. How can I get the vaccine or antibody and which treatment type would be the most effective? I live in Arizona but have no idea how to qualify for the vaccine as a “high risk patient”. Any information would be greatly appreciated, thank you.

    • Starting on January 19th AZ Department of Health is allowing 750,000 Arizonans age 65 and older to sign up for the vaccine (in all counties except for La Paz and Pima). To register, go to or you can call 1-844-542-8201. It looks like all of the vaccines are accounted for through February, but this is where you can go to get more information about getting appointment. You might ask if being high risk includes you in this tier, even though you are not 65 yet.

  • How about this: Forget about the stats, the politics, the reasons and whatever TV channel you watch and 1. Wear a mask, 2. Get your shots ASAP and 3. Be careful + mindful around other people until COVID is gone.

    Basic. Common. Sense.

    Is this too much to ask?

    • Jake, sadly reports have indicated that the rapidly mutating COVID Virus will be ”gone” when the Entire Human Race + All Warm Blooded Animals are no more!

      Until that hopefully far future day happens COVID & its Mutations will ALWAYS be around like the Common Cold and the yearly Outbreaks of Various Influenza Viruses!

      Meanwhile, invest in Companies involved with Protective Face Masks, Respiratory Therapies, E-Commerce, Online Tele-Health, Sequestered Care Facilities, Vaccines & Gene Therapy, and Home Use Virus Test Kits!

    • Why get a vaccine that doesn’t stop you from contracting it, doesn’t stop you from spreading it and is for a disease that 99%+ of the population will have no to mid symptoms and a full recovery from?

  • Learn all the horrifying facts about the Pandemic Blunder in the forthcoming book by Joel S Hirschhorn; the chief screw up was not fully supporting early home treatment that could have saved 70 to 80 percent of covid deaths.

    • I absolutely agree. Early treatment would have been key. Instead, we were told to stay home until hospitalization was necessary. By then your immune system was overwhelmed and the treatment was futile and many times overstimulated your immune system to the point that it attacked your healthy cells as much as the virus cells and contributed to your death. If we treated the sick at the earliest signs of sickness and if we protected the vulnerable, the rest of us could have led normal but cautious lives. Neither of those things were done and still aren’t being done. President Trump’s quick recovery was a prime example of what early intervention could accomplish.

  • OR maybe China’s lying to the world about a virus that started in their country refused to let WHO and the CDC in to help which could possibly have helped contain it or at least spread the word to the rest of the planet that this was no ordinary flu virus. LACK OF INFORMATION KILLS so start with a communist country willing to kill to protect its secrets.

    • Re: “…. so start with a Communist country willing to kill to protect its secrets.”

      Hey! That’s OKAY 👌 because those weaklings that died obviously weren’t Good Strong Healthy Productive Communists anyway!

      Make not so much of a big deal about the deaths of just a few Million “unfortunates” as expected their young children and grandchildren “volunteered” to pick up any slack in production!

      Anyway, within a year the “sadly missing” will be quickly replaced by Party Approved enhanced procreation with selected Healthy, Up and Coming, Eager Young Party Members!

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