Months into a pandemic that has caused more than 500,000 deaths worldwide, scientists are still trying to answer crucial questions about the coronavirus.
Chief among them: everything about asymptomatic patients.
People who contracted COVID-19 but didn't get sick and had no symptoms have been one of the most confounding factors of the public health emergency. The United States has more than 2.5 million confirmed coronavirus cases, but it's likely that many asymptomatic people have fallen through the cracks of official counts.
Now, scientists say that without a better understanding of how many people have been asymptomatically infected, it's difficult to know precisely how they contribute to the spread of the virus and whether they have developed antibodies or other protections that would confer some type of immunity against reinfection.