One official said there was some intelligence that could be interpreted as indications that the hack was linked to Iran, but no evidence was cited. Others said there were many other possible explanations. One official said the intelligence so far was very thin and could point to many suspects, not all of them foreign.

Even so, in a White House packed with officials who are hawkish on Iran, the intelligence was seized upon by some as likely indicating an attack from Tehran.

At the same time, there are growing concerns about a torrent of misinformation affecting everyone from officials at the White House to doctors on the front lines combating the virus.

At emergency rooms in Los Angeles, doctors say they are trying to weed out truth from fiction on social media about how to diagnose coronavirus cases in the absence of tests, and under what circumstances they need to wear protective gear. They say they are spending a disproportionate amount of time scanning social media, trying to gather whatever information they can from anonymous posts by doctors in Seattle, New York and even Italy.

“Right now, we are flying blind, sharing snippets from anonymous doctors over Facebook and Twitter,” said Jennifer Ellice, an emergency room doctor in Los Angeles. “We can’t wait for the usual evidence-based, peer-reviewed data in journals and professional association guidelines.”

Dr. Ellice and her colleagues were pleading Monday for a technological platform, such as a mobile app, that could validate and authorize licensed physicians to share real-time information that would, for example, tell them whether emergency room patients showing extreme gastrointestinal distress may be stricken with the coronavirus.

“We are making policy decisions by word of mouth,” Dr. Ellice said.

Doctors say they were wading through misinformation — what World Health Organization officials call an “infodemic” of lies and rumors — in search of real-time information from doctors around the country.