SARS-CoV-2, the biological pathogen that causes the COVID-19 disease, is a vicious virus.

While much remains to be learned, the new coronavirus seems to be more infectious than the annual flu and possibly more deadly. The unbelievable daily growth in the global confirmed case count speaks for itself.

Indeed, confirmed cases of COVID-19 across the globe now exceed 1 million cases—not to mention the death toll that continues to rise.

But that’s not the end of this pathogen’s perfidy.   

Over the past few weeks, an assortment of new studies have shown that asymptomatic carriers—those who are infected with the virus and “shedding” (or spreading) it, but don’t show any symptoms—may be driving the spread of the disease.

In other words, people who are sick with COVID-19 may be moving around communities unwittingly, rather than staying at home, because they don’t realize they’re ill and potentially contagious to others.

In an interview Monday, Dr. Robert Redfield, director of the Centers for Disease Control and Prevention, noted that “as many as 25%” of infected patients don’t display any symptoms.

By Friday evening, the CDC and the White House’s coronavirus task force had endorsed the public’s wearing of nonmedical cloth face coverings—including masks—to help address this concern, especially when social distancing is difficult.

The new recommendation shouldn’t threaten the supply of protective masks for health care workers.

Elsewhere, a study of roughly 700 infected passengers aboard the Diamond Princess cruise ship estimated that 18% of the cases were asymptomatic. Yet one of the study’s authors noted that the percentage of asymptomatic cases actually could be higher.

Results from diagnostic tests on Japanese evacuees from Wuhan, China, where the new coronavirus originated, show similar findings. According to a study by Japanese scientists, nearly 31% of confirmed cases didn’t show any symptoms.

Another significant finding involves lab testing in Iceland.

The island nation has tested a larger percentage of its population for COVID-19 than any other nation—nearly 5%. These efforts have focused on the broader population, not just patients with moderate to severe symptoms.

Thus far, about 50% of those who tested positive in Iceland haven’t displayed any of the tell-tale flu-like symptoms.

Although scientists have yet to nail down exactly what percentage of coronavirus cases are asymptomatic, the reality is that spread of the disease by those without symptoms is a serious concern. 

Indeed, despite the ongoing development of therapeutics, anti-virals, vaccines, and serological (antibody) testing, concerns regarding asymptomatic transmission provide a compelling case for the administration’s “stop the spread” regimen of social distancing.

The White House last weekend extended the president’s coronavirus guidelines through at least April 30. The “30 Days to Stop the Spread” campaign is another critical step in our battle with COVID-19.

But few disagree that social distancing—really physical distancing—is our best chance to slow or stop the spread, especially given the limited weapons we currently have available in our anti-viral arsenal

The idea of asymptomatic transmission is bad news, but the good news is that we know more now about our invisible enemy than we knew before.

The more we know about the virus, the more efficiently and effectively we’ll wage this war.