CNN  — 

If you show up at NYU Langone Health in New York City with a fever and a cough, they’re going to assume you have the novel coronavirus.

“We don’t care if you’ve traveled to us from China or from Queens, we’re going to put a mask on you,” said Dr. Michael Phillips, an infectious disease specialist at NYU.

The New York University doctors and other experts are convinced there could be more novel coronavirus cases in the United States than have been officially announced. The number of cases in the US increased to 89 as of Monday morning, up from 65 on Friday night.

Several factors, such as testing delays and the fact that the virus can spread before an infected person shows any signs, have led them to this conclusion.

Recent US cases of coronavirus support that theory.

While the US Centers for Disease Control and Prevention has been focused on finding coronavirus among travelers from China and their close contacts, on Wednesday it announced the first US case with an unknown origin. The patient hadn’t traveled to China and had no known exposure to someone with coronavirus. Since then, more cases of unknown origin have been identified in the United States.

“That suggests that the virus is out there in the community, and that means pretty much that everybody’s at risk,” said Dr. Dean Blumberg, an infection disease specialist at UC Davis Medical Center, where one of the California patients is being treated, told CNN affiliate KCRA. “We don’t know who might be carrying it. We don’t know who we can get it from.”

‘An interesting and complicated problem’

Early on in the outbreak, Johns Hopkins epidemiologist Justin Lessler started to think along the same lines as the NYU doctors.