SALINAS (CBS SF) – An E. Coli outbreak that has sickened dozens of people across the country in recent weeks has been linked to romaine lettuce that was grown on the Central Coast, the Food and Drug Administration announced late Monday.

“Based on further discussions with the leafy greens industry and with agricultural authorities, we have begun to narrow the location in which we believe the contaminated romaine in the current outbreak was grown,” FDA Commissioner Dr. Scott Gottlieb said in a statement. “At the time of the outbreak, the vast majority of the romaine on the market was being grown in the Central Coast region of California.”

The FDA said lettuce harvesting has ended for the season on the Central Coast.

Lettuce from the Imperial Valley in Southern California, along with lettuce grown in Arizona, Florida and Mexico has not been connected to the outbreak.

As of Monday, the outbreak has sickened at least 43 people in 12 states. An additional 22 people in Canada have also become ill.

The outbreak prompted officials ahead of the Thanksgiving holiday to take the major step of telling consumers not to eat any romaine lettuce and to advise restaurants and stores not to serve or sell the vegetables.

Gottlieb defended the decision, saying, “The FDA believes it was critically important to have a ‘clean break’ in the romaine supply available to consumers in the U.S. in order to purge the market of potentially contaminated romaine lettuce related to the current outbreak.”

The FDA also announced Monday that major romaine lettuce producers and distributors have voluntarily agreed to place labels indicating where it was harvested, along with the harvest date.