Before states rush to lift lockdowns they should consider the dangers that asymptomatic coronavirus carriers could unleash

• States are reopening non-essential businesses and loosening stay at home orders, but officials haven't accounted for asymptomatic carriers of the coronavirus.
• "If a disease has an asymptomatic state, patients won't seek care, doctors won't test them, and public health authorities won't count them or perform contact tracing," Graham Snyder, of the University of Pittsburgh Medical Center, told Business Insider.
• Testing and contact tracing are critical to "detect asymptomatic infections, interrupt undetected transmission chains, and further bend the curve downward," per the CDC, as is social distancing.
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If you looked at some of the photos that emerged from Central Park and other pockets of New York City over the weekend, you'd have a hard time believing that a pandemic is raging.

Dressed in summer shorts and bathing suits, people soaked in the sun and lounged with friends. Almost no one was wearing a face mask and few observed coronavirus safety guidelines.

NYC was far from the only locale that seemed to have moved on from social distancing over the last several weeks. Protests have also erupted across a broad swath of the US, with thousands demanding to be freed from coronavirus lockdowns so they can return to work. And some states, including Georgia, South Carolina, and Tennessee, have already lifted restrictions and are reopening incrementally.

On Tuesday, Texas Gov. Greg Abbott announced that barbers, hair salons, cosmetologists, and tanning salons can resume business on May 8, and gyms can reopen on May 18.

There seems to be a wave of local and state officials pushing for a loosening of pandemic-related restrictions. The cite dwindling coronavirus infections and deaths. But these officials aren't taking into a count a hidden but vital part of the story: Asymptomatic virus carriers. People who have the coronavirus but have not fallen ill may be among us, silently and unknowingly infecting others.

'The likelihood of a widespread infection is very high'

Already, 1.2 million Americans have tested positive and 70,000-plus people have died from the disease, according to Johns Hopkins University. The US continues to increase its testing capacity, but so far, only 7.5 million people have been tested — a fraction of the 330 million people living in the country.

But Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, said at an April 5 press briefing that "somewhere between 25% and 50%" of people who have contracted the virus may never present symptoms — though they can still pass the illness on to others.

Meanwhile, Dr. E. Blair Holladay, chief executive officer of the American Society for Clinical Pathology, estimated that there are between 100 and 1,000 asymptomatic cases for every one symptomatic case of COVID-19.

"The data is still weak but the likelihood of a widespread infection is very high," he told Business Insider.

That means the real number of patients is likely much higher than the confirmed toll and several developments in April have spoken to that fact. If we estimate based on the number of US coronavirus deaths so far — which as of May 6 was 72,000 — we could conservatively have between 7.2 million and 72 million asymptomatic — but infectious — Americans walking around.

Researchers from Stanford University tested 3,300 Santa Clara County residents for antibodies. which are markers in the blood that show someone has been exposed to coronavirus. Their findings indicate that the number of infections in just that part of the Bay Area was 50 to 85 times higher than coronavirus tests had shown.

Similarly, Gov. Andrew Cuomo said that one in five New Yorkers — or 21% — who were tested for antibodies had them. By that count, more than 2.5 million people across the state have at some point had the coronavirus, far surpassing the official toll of 321,192 cases.

Testing symptomatic patients might not be sufficient

The Centers for Disease Control and Prevention (CDC) also analyzed coronavirus patients in a Washington nursing home and found that only 10 out of 23 people who tested positive had displayed symptoms when they were diagnosed.

"These findings have important implications for infection control," the study said. "Current interventions for preventing SARS-CoV-2 transmission primarily rely on the presence of signs and symptoms to identify and isolate residents or patients who might have COVID-19."

It also pointed out that asymptomatic or presymptomatic spread of coronavirus means that "additional prevention measures merit consideration" because screening and testing for the disease's symptoms may not be enough to wrestle control of the outbreak.

Just this week, nearly 400 workers at Triumph Foods, a Missouri-based pork processing plant, tested positive for the coronavirus, despite a conspicuous absence of symptoms within the group. That was followed by Dr. Raul Pino, the health officer for Orange County, Florida, announcing that 10% of the county's residents who picked up the virus showed no outward signs at all.

And therein lies the problem.

"Asymptomatic carriers are important because they are difficult to identify and contribute to the spread of the disease," Dr. Graham Snyder, medical director of infection prevention at the University of Pittsburgh Medical Center, told Business Insider.

He continued: "Usually for controlling an outbreak we rely on identifying people with symptoms — as we do for COVID-19 — and then test those individuals, advise them on how to keep from infecting others, and perform contact tracing. But if a disease has an asymptomatic state, patients won't seek care, doctors won't test them, and public health authorities won't count them or perform contact tracing."

Since they don't feel unwell, these people may not know that they should stay home from work, stay at least 6 feet away from others, and wear a face mask to curb the spread of the virus, according to Snyder.

Lack of clarity around coronavirus immunity

That said, Snyder pointed out that asymptomatic carriers of coronavirus are "probably less contagious" than those with full-blown symptoms, including fever, body ache, dry cough, fatigue, chills, and loss of smell.

"After all, coughing and sneezing are effective ways for the virus to get into the air and come into contact with other people," he said. "This virus is spread by exhaling small droplets that then come into contact with the eyes, nose, or mouth of another person."

To that, Holladay added, "Asymptomatic people with [the] virus contaminate their hands by touching their face and then contaminate the environment with their hands."

He went on to say that "an asymptomatic carrier will either become symptomatic or immunologically eliminate the infection without showing signs of being sick. The more people who clear the infection and have antibodies to the virus, the less COVID-19 will be prevalent in any given population."

Reopening states prematurely promises to be disastrous

Monday morning, The New York Times reported that the Trump administration is believed to be privately predicting 200,000 new cases and 3,000 deaths every day by early June, based on internal CDC forecasts. That's a dramatic acceleration from the daily increase of 25,000 new cases and 1,750 deaths.

Hours later, researchers at the Institute for Health Metrics and Evaluation (IHME) at the University of Washington nearly doubled their US death forecast, increasing it from where we currently stand at 72,000 to 134,000 by early August. IHME revised its prediction because Americans aren't following existing social distancing rules and states are relaxing their containment measures before curbing the infection's rate of spread has been adequately curbed, Ali Mokdad, a professor of health metrics sciences at IHME, told CNN.

For its part, the CDC says that the existence of asymptomatic transmission has "several implications" for containment since people don't know that they're sick to begin with. You can't treat what you don't know you have, after all.

Asymptomatic transmission, CDC researchers wrote, "enhances the need to scale up the capacity for widespread testing and thorough contact tracing to detect asymptomatic infections, interrupt undetected transmission chains, and further bend the curve downward."

Simply put, Snyder said, "asymptomatic transmission is a concern because it may perpetuate the epidemic" and undo any progress states may have made in controlling the virus's spread. Lifting lockdowns prematurely would be catastrophic — not only because it could trigger a surge in new cases and deaths, which would overwhelm hospital systems and plunge the economy even further into a recession, but also because the US could exhaust its medical equipment reserves, including ventilator capacity, by June.

Which is why increasing our testing capacity is so critical.

Synder would like to see a ramp-up in the testing of asymptomatic people and a greater emphasis be put on contact tracing, though it may be difficult given the profound shortages of coronavirus tests we're already seeing.

But until those measures are put in place, Synder said, "The only way to control it is through social distancing and masking — so even if you have the virus and don't know it, it will be less likely to spread."