Since at least Jan. 3, the two countries have waged cyberattacks against a range of American firms and institutions that are working to find a vaccine for Covid-19, the disease caused by the coronavirus, officials said.

The attacks have raised the prospect among some officials that the aggression could be viewed by the Trump administration as a direct attack on U.S. public health and tantamount to an act of war, they said, because the attacks may have hindered vaccine research in some cases. Such an interpretation would represent an escalation of how the U.S. government views cyberattacks against the country.

The issue has sounded alarms across the government. The Federal Bureau of Investigation and the Cybersecurity and Infrastructure Security Agency, the cyber wing of the Department of Homeland Security, on Wednesday are expected to issue what officials called a “public service announcement” with respect to China, saying Beijing is sponsoring widespread cyberattacks intended to steal vaccine research. The FBI and DHS declined to comment.