Federal officials are reporting that an outbreak of E. coli O121:H9 infections linked to romaine lettuce has ended.

Four illnesses were confirmed in the outbreak. Little other information was available from the Food and Drug Administration.

“The information collected over the course of this investigation indicated that romaine lettuce was the likely source of this outbreak; however, it appears that this outbreak is over, and there is no actionable advice for consumers,” according to FDA officials.

“FDA has been conducting a traceback investigation and other activities in an effort to learn more about possible sources or routes of contamination.”

The FDA first reported the outbreak two weeks ago but has not shared any information about patient demographics or what states are involved. The agency did not report when the first illness was reported or when the last one was logged by public health officials.

As of Jan. 26, the Centers for Disease Control and Prevention had not posted any information about the outbreak. That is generally standing procedure for the agency if a specific product is not identified.