The CDC is warning that asymptomatic people are contributing largely to the spread of COVID-19.
Symptoms typically include coughing, fever, and shortness of breath.
During the time when people are unaware that they have contracted the virus, they are highly infectious and may unintentionally spread the virus to others.
Some people may also test positive but never show any symptoms.
"Most SARS-CoV-2 infections are spread by people without symptoms," the CDC wrote. "CDC and others estimate that more than 50% of all infections are transmitted from people who are not exhibiting symptoms. This means at least half of new infections come from people likely unaware they are infectious to others,” the agency added.
Since people may be infectious but not display symptoms, the CDC stresses wearing masks as a key tool in slowing the spread.
The agency emphasized that all masks, both medical and non-medical, protect the wearer from respiratory droplets.
“The prevention benefit of masking is derived from the combination of source control and personal protection for the mask wearer,” the CDC said, adding that cloth masks effectively block large droplets along with fine droplets and even particles.
The CDC concluded: “Adopting universal masking policies can help avert future lockdowns, especially if combined with other non-pharmaceutical interventions such as social distancing, hand hygiene, and adequate ventilation.”
Earlier this week, Dr, Anthony Fauci director of the National Institute of Allergy and Infectious Diseases, said it will still be essential to wear face masks, practice social distancing and follow COVID-19 guidelines after a vaccine becomes available in the United States.
“Because even though for the general population it might be 90 to 95 percent effective, you don’t necessarily know for you how effective it is,” he explained.